The Element – Summer 2022

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The Element

Summer 2022

A note from the Chemistry Team…

Welcome to the second edition of Godolphin’s The Element magazine!

This magazine was created by a group of LVI with the help of Ms Swann to put together a range of articles that we hope you will find very interesting and help you see the world through a different, scientific lens.

In this issue we have articles ranging from the chemistry behind plastic recycling, breastfeeding and even chocolate. We hope you have lots of fun reading our articles and enjoy our activity at the end!

Editor

Valentina Lesmes Campins

Writers

Ingrid Loynes Annika Tang Cassie Wigoder Dorian Gilzene Sofia Cullinane Ava Barkle Lulu Aberg Grace Kaprielian Sofia Waring Dillan Rosen

Cover by

Aitana Blanes-Easo

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Contents

Antimony

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Physical vs Chemical recycling of plastic

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The biochemistry behind Breastfeeding

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Chemistry behind Fireworks

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Chemistry behind Teeth Whitening

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The chemistry behind Cosmetics

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The chemistry behind Hair Dye

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The chemistry behind how Alcohol affects the Body 20 How Iodine in desert dust destroys Ozone

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The Chemistry of Chocolate: From Bean To Bar

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Chemistry Crossword!

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Antimony If you have never heard of antimony, it’s probably because it’s not one of elements you come across often at school, or even hear about much in the outside world. Its history, however, shows that its discovery in ancient times had real significance, but has seemed to be a mysterious metal to the mainstream world.

12th century illustration of a Byzantine ship using Greek fire in around the year 821 (https://en.wikipedia.org/wiki/File:Greekfire-madridskylitzes1.jpg)

The name ‘antimony’ is derived from the Greek words ‘anti’ and ‘monos’, together meaning ‘not alone’. This references the fact that antimony is almost always found in nature in compounds, and almost never as the element itself.

In Ancient Rome, however, antimony (in Latin, ‘stibium’, which is the reason for the chemical symbol Sb) was used medicinally for dermatological illnesses and burns, clearly very different from its use in Ancient Greece. In the world of medicine, antimony’s use in history has extended much further than dermatology, a fact particularly interesting considering that the element is in fact toxic. The symptoms of antimony poisoning are similar (but generally milder) than the symptoms of arsenic poisoning.

However, some of its historical medicinal applications found ways to get around this significant limitation, and in some cases even use its toxicity for the benefit of medicinal technique.

Antimony was used widely as an emetic (a substance which induces nausea) in the 18th century. A piece of antimony would typically be left in a goblet of wine for a period of a few hours, allowing the wine to absorb some of the antimony which could then be used as an emetic, while at the same time not absorbing so much antimony that the patient would be poisoned. Although this and similar techniques were commonly used at the time with extreme caution, there were cases reported of people being poisoned by the medicine that was meant to help them, one famous case of this being the death of the composer Mozart. Although the true cause of Mozart’s death is not known and has several theories surrounding it, one theory involves antimony poisoning. Doctors had prescribed

Antimony (https://commons.wikimedia.org/wiki/File:Antimony-4.jpg)

Its uses have been recorded as early as in Ancient Greece, where it is thought to have been a component of Greek fire, an incendiary weapon which was used in military battles. The specific antimony component in ‘Greek fire’ was antimony sulphide, which reacts vigorously with oxygen, fitting in with the description of Greek fire as being very dangerous and destructive.

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Mozart antimony tartrate, and it is thought that he took a dangerous quantity of this compound, leading to his death. His condition just before his death included symptoms of ‘severe vomiting’ and a fever, consistent with the symptoms of antimony poisoning.

You may be thinking, though, that these symptoms of vomiting and fever could be attributed to a variety of illnesses, for example the flu, and wouldn’t immediately have been considered to be the result of poisoning. This ambiguity over the cause of symptoms was used by criminals during the 19th and 20th centuries.

The criminals would poison their victims with antimony, ultimately with the hopes that their deaths would be passed off as the result of a bad stomach infection instead of preplanned murder.

Since the toxicity of the element was not as famous as the toxicity of arsenic, for example, the murder cases using antimony were sometimes not solved for long periods of time, with the deaths being ruled as unlucky accidents.

‘Perpetual pills’ - reusable antimony laxatives from the Middle Ages (https://dangerousminds.net/comments/perpetual_pills_the_reusa ble_laxatives_of_the_middle_ages)

The current-day uses of antimony are very different from the historic uses discussed and could be said to be much less interesting - today antimony is commonly added to metals to create alloys which increases the hardness of the metal.

Antimony sulphide is often used in the camouflage paint, whereas antimony trioxide is used in flame-proofing compounds. It is even used in semiconductors, showing the variety of uses in the present day.

The most interesting (and arguably most random) use of antimony, however, is one that was used in the Middle Ages - the reusable laxative. An antimony pellet would be ingested, the toxicity of the antimony disturbing the bowels during digestion. Finally the pellet would then be egested, and could then be recovered and reused. It was this reusable property of the antimony pellets that led them to be nicknamed ‘perpetual pills’.

Although it might not be the most well known element, antimony’s uses have been valued by many people in history, and by many of us today, even if we don’t know it. With the variety of applications, it could be interesting to see some of the historic uses in the present day. Maybe not the reusable laxative though.

By Ingrid Loynes Sources: https://dangerousminds.net/comments/perpetual_pills _the_reusable_laxatives_of_the_middle_ages

Book : ‘The Periodic Table’ by Paul Parsons and Gail Dixon

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Physical vs Chemical recycling of plastic

Out of the fraction of plastic that are given a new life again by recycling, once they are used and thrown away again, it is often the case that they are unable to go through plastic recycling once more. This is due to the way that they are recycled, being namely, physical or mechanical recycling.

Plastic is one of the most common and most used materials of our time. Its properties of being lightweight,ability to be moulded easily as well as the cheap manufacturing process place it at a point where it is essential to our lives. From plastic bags and plastic packaging to parts in cars, we use plastic a lot more than we realise. But everything comes with both plus sides and down sides, and for plastic, its disadvantages are the problems we face with plastic pollution and rubbish. Plastic pollution leads to millions of animals being killed including anything as small as corals to animals as big as whales [1].

As the more known and practised way of plastic recycling, physical recycling is the method in which plastic is grounded up and remoulded, keeping its initial molecular structure throughout this process. For this type of recycling to occur, plastics must be cleaned and uncontaminated, otherwise, the whole batch may be rejected and dumped into landfill. As well as this, problems with the type of plastic that can be recycled cause this type of recycling to be fairly limited in its ability to solve plastic pollution.

(Image from https://www.nationalgeographic.org/article/whopping-91-percent-plastic -isnt-recycled/)

Despite the idea of plastic recycling coming into play to try and tackle these problems, not all plastics are recyclable and many that are, end up in landfills anyway. The UK is one of the countries that has placed much effort in terms of its attempts to improve plastic recycling and sustainability, with the UK coming in 10th in Europe for plastic packaging recycling rates [2] . However, despite this, we are still seeing around three-quarters of an estimated 4.9 million metric tons of plastics placed on the market each year becoming waste [3] .

(Image from https://www.suedpack.com/en/consultation/sustainability/chemical-recy cling/ )

On the other hand, another proposed way of plastic recycling, chemical recycling, seems to have some better qualities and if it does turn out to work, could very much allow us to succeed in our attempts of creating sustainability with our plastics. Chemical recycling is the process in which long hydrocarbon chains can be broken down into smaller hydrocarbon chains and even single 5

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monomers (single hydrocarbon units) by using certain chemicals like Sulfuric acid and Hydrochloric acid. This allows for no restrictions as to what the recycled plastic can be used for as the monomers can be remade into a new polymer chain and reused. Physical recycling is said to be ‘down cycling’ plastic while chemical recycling can allow for ‘upcycling’ of plastic. Furthermore, the idea of chemical recycling being able to allow plastics to be recycled infinitely as well as it not requiring the careful sorting of uncontaminated plastic, makes the process very appealing in the waste recycling industry. It also allows for cheaper products as plastics that are physically recycled show to be more expensive than the original plastic produced. Through projects like Innovate UK, funding 1.2 million pounds for further development on chemical recycling technologies [4] , we can see that it is a process that has been highly valued.

Despite this, it does seem that there are multiple companies out there that are trying to achieve success in chemical recycling attempts. These include Agilyx, Alterra, Amsty, Arcus, Basf Chemcycling, BiologiQ, BP, Braskem, Clariter and much more [6] .

Therefore, whilst there may still be debate over the topic, it does seem that further development in chemical recycling and encouraging its use would allow there to be steps taken forwards, towards less wasteful and less harmful plastic usage.

By Annika Tang

(Image from https://pubs.rsc.org/en/content/articlelanding/2020/py/c9py01927h)

As this way of recycling is still in its early stages, some think that when chemical recycling is put into action, the initial upsides of this process that were put forward may not prove to be true. This involves ideas of how chemical recycling might not lead to plastic that can be infinitely recycled, despite it being proposed to do so. On top of this, problems of chemical recycling, such as it having higher carbon emissions as well as a higher use of energy than the traditional way of recycling plastic [5] , make some less optimistic about the process.

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Citations

Further information on chemical recycling:

[1] Two Oceans Aquarium,The plastic problem: How does plastic pollution affect wildlife?,Aquarium.co.za,

https://theconversation.com/plastic-pollution-why-c hemical-recycling-could-provide-a-solution-129917

https://www.aquarium.co.za/blog/entry/the-plastic-p roblem-how-does-plastic-pollution-affect-wildlife

Chemical recycling process: https://www.bpf.co.uk/plastipedia/chemical-recyclin g-101.aspx

[2] British Plastics Federation, Plastic Recycling, Bpf.co.uk, https://www.bpf.co.uk/sustainability/plastics_recycli ng.aspx

Physical plastics recycling process guide:https://www.bpf.co.uk/plastipedia/sustainabili

[3] Ian Tiseo, Statista, Top Plastic waste in the UK, Nov 22, 2021, Statista.com,

ty/how-is-plastic-recycled-a-step-by-step-guide-to-r ecycling.aspx

https://www.statista.com/topics/4918/plastic-waste-i n-the-united-kingdom-uk/#dossierKeyfigures

Contamination in the physical recycling process:

[4] News, Innovate UK backs £1.2M project to further develop chemical recycling technology, 15th February 2021, recycling technologies.co.uk,

https://metro.co.uk/2018/02/15/happens-dont-bothe r-washing-recycling-7315366/

https://recyclingtechnologies.co.uk/2021/02/innovat e-uk-backs-1-2m-project-to-further-develop-chemic al-recycling-technology/

Different views on chemical plastic recycling (against): https://www.forbes.com/sites/emanuelabarbiroglio/2 020/06/06/chemical-recycling-wont-solve-the-plasti c-crisis-study-finds/?sh=215e30dd53d6

[5] Alex Barrett, Bioplastics News, Mechanical vs Chemical Recycling, November 20 2020, Bioplasticsnews.com, https://bioplasticsnews.com/2020/11/20/differencemechanical-chemical-recycling/

https://www.forbes.com/sites/emanuelabarbiroglio/2 020/06/06/chemical-recycling-wont-solve-the-plasti c-crisis-study-finds/?sh=215e30dd53d6

[6] Bioplastics News, Chemical Recycling Companies, bioplasticsnews.com, https://bioplasticsnews.com/chemical-recycling-co mpanies/ Further reading

Agilyx interview on chemical recycling: https://packagingeurope.com/agilyx-interview-movi ng-chemical-recycling-forward/

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levels of oxytocin increase in times of bonding between parent and child such as skin to skin contact, in childbirth, and whilst hugging. It is a protein made of nine amino acids (a nonapeptide) in the sequence: cysteine-tyrosine-isoleucine-glutamine-asparag ine-cysteine-proline-leucine-glycine-amide.

Oxytocin is made in neurosecretory cells, in the hypothalamus, and is released into the blood from the pituitary gland. After birth, suckling by the baby is relayed by spinal nerves to the hypothalamus. The stimulation causes neurons to secrete oxytocin in intermittent bursts. This triggers the milk ejection reflex also known as ‘let down’. In this scenario, oxytocin causes the cells around the milk-filled alveoli to contract and squeeze milk out through the milk ducts to allow the baby to feed.

The biochemistry behind Breastfeeding After a person has given birth, one of the first natural maternal instincts is to hold the baby up to their chest so it can do one of the main things required for human survival - to eat. The breast milk produced contains supplements to nourish and give the newborn baby what it needs to survive. However, the body must first find a way to produce and release it. This process is facilitated by the hormones prolactin and oxytocin.

Prolactin is a polypeptide hormone made of 199 amino acids, and is produced by the pituitary gland in the brain. In humans, the prolactin molecule is arranged in a single chain of amino acids, with three intramolecular disulfide bonds between six cysteine residues (another type of amino acid). It starts to be released during the end of pregnancy, but high levels of oestrogen and progesterone counteract its effects. After birth, the levels of oestrogen and progesterone drop rapidly which allows prolactin to stimulate the production of breast milk. This is known as lactogenesis.

Prolactin causes the lactocytes (the milk producing cells on the alveoli in the breasts) to take proteins, fats and sugars from the blood supply in order to produce breast milk.

Oxytocin is often known as the ‘love drug’ or the ‘cuddle hormone’ and is associated with empathy, trust, and relationship-building. The 8

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Breastfeeding works on a supply and demand regime through the use of a small whey protein found in breast milk called Feedback Inhibitor of Lactation (FIL). FIL is thought to slow milk synthesis. Therefore, when the breast is full of milk, there is more FIL and less milk is produced. When the breast has less milk, there is less FIL and milk production speeds up.

will aid growth, activate the immune system, and develop and protect neurons in the brain.

Whilst the exact chemical profile of breast milk is still unclear, there are a multitude of components we know that are necessary for a baby’s growth and development. Millions of live cells, including white blood cells and stem cells, boost the baby’s immune system and help organs develop and heal. Antibodies from the mother, either through vaccinations or infections, flow directly to the baby and help protect it against illnesses and infections - this is known as passive immunity.

Finally, carbohydrates make up a wide portion of the breast milk as it provides the baby with the energy needed to survive. Most of this is in the form of lactose (a sugar) that provides 40% of the baby’s calories through its breakdown, by the enzyme lactase, into the sugar molecules glucose and galactose in the gut.

The other type of carbohydrates are oligosaccharides. These are polymers consisting of a small number of simple sugars that act as probiotics in the gut and help prevent infections. They are the third largest solid component of breast milk and the key differentiator between human and cow milk.

Many hormones (proteins that carry messages to organs and tissues) are vital components of breast milk. Thyroid hormones control the baby’s metabolism, endorphins act as natural painkillers, and leptin controls the baby’s appetite, weight and how much energy it uses.

Enzymes will act as catalysts in the baby’s metabolic reactions, such as aiding digestion and absorption of iron. There are also supplementary mineral ions in breast milk such as Na+, K+, Ca2+, Mg2+, and Cl- that support healthy growth and organ function, and help build the baby’s teeth and bones.

2’ - Fucosyllactose is one of the 150 oligosaccharides found in human milk. It makes up most of the human milk oligosaccharides (HMOs) found in infant formula as it is easy to mass manufacture using fermentation and is safe and effective.

HMOs were not used in infant formula until around 2015. Infant formula is largely composed of cow’s milk that has been treated to make it more digestible for babies.

Polyunsaturated fatty acids (long hydrocarbon chains that contain a double bond) such as the fats found in vegetable oils, nuts and seeds, are also found in human milk. This fat is characterised by high contents of palmitic and oleic acids. They are used to build the baby’s nervous system and aid in eye development.

Free amino acids such as Taurine, glutamic acid, and glutamine also help make up the breast milk, in addition to the amino acids that build proteins such as whey and casein. These

Whilst breastfeeding has an array of benefits, it is not a process that is available or beneficial to many mothers. The increasing popularity and quality of infant formula due to more research on chemical synthesis of products of human milk has led to feeding becoming a much more accessible process for many. Many report that birth and breastfeeding can feel like 9

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a completely daunting, unknown experience, and it can be useful to know the changes and processes happening inside your body in order to provide for another.

By Cassie Wigoder

Sources: https://medlineplus.gov/lab-tests/prolactin-levels/ https://wicbreastfeeding.fns.usda.gov/how-breast-m ilk-made https://www.chemistryworld.com/features/the-scien ce-of-breast-milk-and-baby-formula/4014574.article https://www.medela.com.au/breastfeeding/blog/awe some-breast-milk-facts/how-breastfeeding-actuallyworks-exploring-the-science-of-breast-milk-feeding https://journals.physiology.org/doi/full/10.1152/phys rev.2000.80.4.1523 https://www.worldofmolecules.com/emotions/oxytoc in.htm https://www.medicalnewstoday.com/articles/275795 https://www.medela.com/breastfeeding/mums-journ ey/breast-milk-composition https://pubmed.ncbi.nlm.nih.gov/392766/

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‘hazard types’: HT1, HT2, HT3 and HT4, with HT1 being the most dangerous. HT1 and HT2 are not sold in common stores.

Chemistry behind fireworks

Concerning the make of a basic firework, gunpowder is needed. There are three reagents which make up gunpowder potassium nitrate, carbon and sulphur. The most important part of the gunpowder is the potassium nitrate as this is what propels the firework into the sky. A fuse is used to light the gunpowder, igniting the firework and thrusting it into the sky.

Fireworks come in all sorts of shapes, colours and sounds, and are used to celebrate different occasions all over the world. Have you ever thought about how they work? Well today, this article will explain the science behind how they work.

Historians believe that fireworks originated in ancient China in the second century B.C. It is thought that these natural firecrackers were bamboo stalks that, when thrown in a fire, would explode with a bang because the hollow pockets in the bamboo were overheated. This became a tradition as it was said to ward off evil spirits and is still done today at Chinese New Year.

Other components are required for the firework to shoot into the sky: fuel, an oxidiser, and a binder (not to mention the plentiful supply of oxygen in the atmosphere). The fuel stores energy as it’s a source of electrons and essentially burns up during the explosion ( charcoal is typically used as fuel). Next a chemical reaction (usually combustion) takes place between the fuel and the oxidiser (an oxidising agent oxidises another substance by gaining electrons from the other substance and it itself is reduced). Upon this reaction, the electrons are being transferred between the two substances - creating a lot of stored potential energy which is then ready to be released. The binder is a substance that holds these components in place to ensure the explosion does not go off unexpectedly as well as reducing the sensitivity to both shock and impact. The binder is typically used to engineer the timing of the explosion to coordinate with others in a fireworks display.

(https://www.historyhit.com/the-history-of-fireworksfrom-ancient-china-to-the-present-day/ )

While in the sky, a combustion reaction takes place between the reactants and a detonation explosion occurs. As they react, the products formed are solid potassium carbonate, solid potassium sulphate, nitrogen gas, and carbon dioxide gas. Finally, the explosion spreads out all of the material, all while being under a superheated state.

More and more people have experimented with fireworks and they have evolved to use all types of ingredients and all sorts of styles.

Infact, there are 19 different types, all with their own colours. However, with evolution comes danger, and there are now very large and dangerous fireworks; there are four categories of fireworks which are ranked in order of 11

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Now, if this type of firework were to be sent into the sky, there would be a loud ‘bang’, however there wouldn't be any light or colour. The components responsible for creating a dazzling spectacle of light and colour are metal compounds - particularly metal salts.

These compartments explode at different times making different patterns. The pattern of stars around the central gunpowder also creates different patterns of fireworks. For example, if the stars are in a circle around the gunpowder, a circle display of colour is shown in the sky.

These are placed with a lot of precision!

Metal salts within the metal body of the firework are often coated with gunpowder to aid with the ignition. As the reaction creates heat, the electrons in the metal become so excited that they travel back and forth between higher energy levels (shells) and their original energy levels (shells). The excess energy emitted when the electrons fall back down to the lower energy level is visible light energy.

Different metals will have larger or smaller gaps between their ‘excited’ energy level states and original energy level states, which causes emissions of different colours (this is also what happens during flame tests on different metals).

Although metals are in salt forms, due to the easier dispersion and typically more stable states, there are some colours which are difficult to produce due to the unstable nature of the metal. For example, copper salts at high temperatures tend to be unstable. If such high temperatures are reached, it breaks apart and the blue colour is not exhibited. Purple colours are also tricky to produce as red producing compounds (strontium) and blue producing compounds (copper) are required in combination.

There are other limitations which those preparing fireworks have to be careful of.

Firstly, the reactants cannot collect moisture in the air, as otherwise it won't burn properly, so they must be stored dry. Secondly, the fireworks should not expel any toxic substances into the atmosphere. This means all compounds must be benign (safe to use).

For example, blue colouring previously used in fireworks many years ago contained arsenic, which is lethal to humans when ingested.

As shown above, there are many complicated (and quite dangerous) events which take place during a firework show. When you go to your next firework display, it’ll be like watching it for the first time, now that you’ll be able to appreciate the work and science behind it! This overview has hopefully presented an interesting insight into the science behind fireworks.

(https://www.compoundchem.com/2013/12/30/t he-chemistry-of-fireworks/amp/ ) The metal compounds are put into ‘stars’; the pattern shown in the sky depends on how the ‘stars’ are arranged. For example, if the body of the firework is made up into sections, the stars can be put into different compartments.

By Dorian Gilzene 12

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Sources: https://penntoday.upenn.edu/news/chemistrybehind-fireworks

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Chemistry behind teeth whitening

The tooth stains often fall into two categories, intrinsic, where the colour difference occurs within the tooth, and extrinsic, where the colour inconsistency occurs on the surface of the tooth. The actual compounds that cause the colour disparities are called chromogens which are either metal containing elements or large organic compounds that contain alternating single and double bonds. When the teeth have colour due to the latter reason, they are whitened with hydrogen peroxide which reacts with the double bond to oxidise it. This oxidation causes the chromogens to become lighter in colour. When the colouring is caused by chromogens containing metal elements, it is much harder to remove this colour so the teeth need professional products that contain chemicals like sodium hypochlorite (NaOCl).

This operates in the same way that hydrogen peroxide does by reacting with the double bonds in the chromogen, however often the end result isn’t usually as white as desired so people tend to opt for veneers or composite bonds as an alternate method of achieving whiter teeth.

It’s no lie that over the past few years we have become more conscious about the way we look, dress, and present ourselves, so are more willing to make adjustments to our appearance. Many surveys done by dental companies have found that the first thing people notice when they look at someone is their smile. It is therefore understandable why people spend years and years perfecting it, using composite bonds, veneers and braces until they are satisfied with their shape, alignment and nowadays even colour. The once ‘natural’ colour of teeth has been overlooked with a new pristine white colour that can almost only be achieved through the use of some form of whitening, unless you are of course the woman from the Colgate adverts who only eats apples and manages to maintain the crisp, pearl white colour through just brushing her teeth. However, whilst whitening might appear to just be lightening the colour of our teeth and leaving a more pleasant colour, the act of whitening can also cause damage to your teeth if not done correctly.

There is general awareness that teeth whitening can affect the sensitivity of your teeth, however scientists have recently found that there are other risks that can occur through the process of whitening. Some of these include tooth surface roughening and softening and increased risk of demineralization especially with the enamel in your teeth.

There are many different methods and products that can be used to achieve different levels of lightness. For lighter stains, a simple toothpaste can be used, but for more severe stains, it's best to get them professionally whitened. For the more milder cases, one might opt for whitening strips and gel, whitening toothpaste or whitening rinses.

Whitening toothpastes don't contain sodium hypochlorite but in some cases they may contain low concentrations of hydrogen peroxide. Because of this, whitening

The general process of teeth whitening often involves the chemical hydrogen peroxide (H2O2) which is also commonly found in the form of carbamide peroxide - a compound that breaks down in contact with water to release hydrogen peroxide.

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toothpastes generally only lighten the teeth by one or two shades. Whitening strips and gels are peroxide based and are often left on the teeth for a substantial period of time to see the effect of lightening - much like toothpaste this usually only lightens by one or two shades. A whitening rinse contains hydrogen peroxide or another form of oxide; however, this process generally takes a much longer time to see the same effect as some of the other methods.

the chromogens which appear in coffee, red wine, cigarette smoke and many other things that we wouldn't think twice about putting in our mouths. However, the damage whitening causes isn’t believed to be that serious so dentists will continue to recommend the treatments if the patient desires them.

By Sofia Cullinane

Another method of achieving this highly desired white smile is through the use of blue light. This can be done in the dentist with highly specialised equipment; however, in this day and age, more will opt for an at home kit in which you are given your own small blue light machine to do the procedure yourself. This form of whitening focuses on a bleaching property of chemicals like hydrogen peroxide or carbamide peroxide in the form of a whitening gel. This is first put on your teeth and does the actual whitening of your teeth, but it is believed that the addition of using a blue light speeds up this reaction as it activates the product while on the teeth and causes an increase in the rate of chemical reactions.

Typically, a higher concentration of hydrogen peroxide can be found in the gel because of its professional usage which also provides a more visible colour difference.

Sources: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC 4058574/ https://www.daybreakdentalcare.com/blog/scie nce-behind-teeth-whitening

Researchers have found that the mild use of teeth whitening doesn't cause that much harm to the teeth however aggressive teeth whitening can cause changes to the tooth’s microstructures and restoration changes. It can cause reactions between ceramic crowns and composite restorations, in turn reducing the stability of the teeth. It can also change the microstructure of enamel crystals (which provide enamel with their mechanical properties).

The best way to avoid all this damage is to fully avoid teeth whitening which can be hard due to 15

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ingredients and form emulsions for consistency. However, the water must not be everyday tap water. It cannot contain microbes, toxins and any other pollutants, so only distilled, purified water is used as a base.

The Chemistry Behind Cosmetics A cosmetic is defined as a preparation applied to the body, especially the face, to improve its appearance. Cosmetics play a very key role in many people's daily lives; these products are created to cleanse and modify our external appearances. Ingredients, such as water, emulsifiers, preservatives, colours and fragrances, can be both artificial and naturally occurring. Any impact that these ingredients could have on our health is dependent on the chemical compounds that they are formed from, and any dose of potentially dangerous chemicals found in cosmetics are regarded as too small to pose any risk to human health.

Here are some examples of ingredients that are used in cosmetics and how they link to chemistry: Emulsifiers which are used in creams and lotions help to keep miscible substances from separating, for example water and oil. As many cosmetic products are based around emulsions, and since oil and water do not mix whatsoever due to hydrophobic properties, emulsifiers can be added to change the surface tension between the oil and water. This then produces a homogeneous and easily mixed product, that has an even texture. An example of an emulsifier that is commonly used in cosmetics is polysorbates, used in foundation.

Pigments, which can be used to accentuate or even alter a person’s natural colouring are also commonly used. There is a huge range of substances that are able to produce a rainbow of colours which you can see in cosmetic stores. Mineral ingredients used may include: iron oxide, manganese and chromium oxide. In addition, natural colours can be found from plants such as beet powder or from animals.

Pigments can also be organic, this means they are carbon-based molecules whereas inorganic pigments tend to be metal oxides and these pigments usually are brighter and last longer than organic ones.

Cosmetics are definitely not a modern invention; Humans have been using many different types of substances to accentuate and alter features and appearances for over 10,000 years. For example, women in Ancient Egypt used to use ‘kohl’, which is a substance that contained powdered lead sulphide, to darken their eyelids.

Another example is in Greece, where women used to put poisonous lead carbonate on their skin to gain a pale complexion.

Fragrances play a huge role in how popular cosmetics are. Chemicals, which can be both synthetic and natural, are added to these products to achieve a more appealing and pleasant fragrance. Even products advertised as “unscented” may contain fragrances to hide any other chemical smells! Even one listing of

Cosmetics can range from foundation to deodorant to hairspray. They tend to contain water as it plays a very important role, often acting as a solvent to dissolve other 16

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fragrance on a product's ingredients list may mean there could be hundreds of chemical compounds that created the final one fragrance. Esters are popularly used in fragrances due to their naturally pleasant scents. For example, Pentyl Nonoate smells like roses, and Propyl Octanoate smells like coconut. An ester is a compound that is formed from a condensation reaction that happens when there's a combination of a carboxylic acid and an alcohol. The exact combination of the type of alcohol and the type of carboxylic acid will determine which ester is produced.

which was incorrect. Currently, the use of parabens in cosmetics is considered to be safe internationally.

By Ava Barkle

References: https://www.thefactsabout.co.uk/science-behin d-cosmetics http://www.aquimicadascoisas.org/en/?episodi o=the-chemistry-of-cosmetics

Another extremely important ingredient is preservatives, as they extend cosmetics shelf life and also prevent the growth of microorganisms that could harm the user and ruin the product. Most microbes live in water, therefore, preservatives need to be water-soluble due to the water base of most cosmetic products. They can be either natural or synthetic. Some popular preservatives are benzyl alcohol, salicylic acid and formaldehyde.

Parabens are a class of chemicals that can be used as preservatives in cosmetic products(or even in food). Para Hydroxybenzoic acid (PHBA) is where the word parabens comes from, this acid is found naturally in many fruits and vegetables. The forms which parabens come in can vary, for example there is methylparaben and also isobutylparaben. They keep products bacteria and mould free. The use of parabens in cosmetics became highly discussed after a research study from the University of Reading, which reported findings that 18 out of 20 breast cancer tissue samples contained parabens. Parabens slightly mimic the actions of oestrogen, and therefore it was thought to be a problem because this hormone can enhance tumour growth. The presence of these parabens in breast tumours was presented by the media as evidence that parabens can contribute to breast cancer, 17

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The chemistry behind hair dye The concept of being able to change hair colour is fascinating, and there are many different types of ways to do it.

Foremost, the molecules that cause our hair to be coloured in the first place are pigments called melanin or more specifically, eumelanin and pheomelanin. Eumelanin is the pigment in charge of brown and black shades and pheomelanin gives blonde to red shades. This means that darker hair contains more eumelanin (the more abundant type) and lighter hair colours contain primarily pheomelanin. Different shades of hair colour simply depends on the ratio of concentrations of the two pigments.

(Loved By CurlsWhat Happens If You Mix Conditioner with Hair Dye?)

Temporary hair dye is quite popular for those who want a short term change. It does not actually change the natural hair colour as the dye does not penetrate the cuticle at all, it merely attaches itself to it, meaning that they don’t damage the hair at all. This means that after a certain amount of time, the colour will be washed out as the hair is washed. However, these conditions also means that temporary hair dye is not effective on people with naturally dark hair as the dye on the cuticle does not show. Common examples of temporary hair dye are hair colour sprays and hair chalk; these both wash out in one wash meaning they are very short term.

The hair is structured as concentric cylinders made up of three layers. The outer layer is the cuticle which is transparent and protects the cortex, made up of lots of overlapping dead cells. The middle layer is the cortex, which provides the strength, moisture, colour and texture to the hair (melanin is found in the cortex) and the inner layer is the medulla, which is the core of the hair and may be absent in some cases.

Now that we know a little about the chemistry of natural hair, we can talk more about dyeing them. As many will know, there are different ways to change the colour of your hair, ranging from temporary dye to permanent dye.

Semi-permanent hair dyes are perfect for those who wish to have a longer lasting change and they’re also great for grey hair coverage. They penetrate the cuticle without reaching the cortex and covering the natural pigments (this could be a downside as it limits the colour palette meaning those with darker hair may find it difficult to work with this type of dye). They do not damage the hair structure at all which is a bonus but the colour fades and disappears after usually four to six weeks.

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The chemistry behind permanent dyes is a little more complicated as there are a number of new chemicals involved in permanent dyes, of which some are what harms the hair. First of all, the natural pigments in the cortex must be removed and replaced with dyes for the colour to stay permanently, which is why this is the most effective way for those with dark hair to change their hair colour. In order to do this, the cuticle is opened and lifted by using an alkaline chemical with a pH of around 10, usually ammonia. Next, in order for the dye to show more prominently, hydrogen peroxide (commonly known as bleach) is used to lighten the hair. This is done by oxidising melanin, essentially reacting with the melanin and turning them into colourless chemicals. Now, small precursor molecules (the dye) are soaked into the cortex through the open cuticle and they react with one another, forming larger molecules too big to escape the cuticle layer.

Consequently, the cuticle is closed by an acidic conditioner but it is more damaged and fragile in comparison to the start.

Although permanent hair dyes do not need to be reapplied, they can not be washed out if you decide the colour isn’t that great anymore, unless the hair is bleached again and recoloured or you could wait until new hair grows out. Continuous bleaching distorts the cuticle layer repeatedly, damaging the hair more and more due to the toxic chemicals used, which is why it is advised not to excessively bleach your hair.

By Lulu Aberg

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bloodstream and can travel around the body very quickly. Alcohol is distributed through the body via the bloodstream, so most tissues are exposed to the same concentration of alcohol as in the blood. An exception of this is the liver which digests about 90% of alcohol before it passes through into the rest of the body.

The Chemistry Behind How Alcohol Affects the Body Many of us may be familiar with the typical symptoms after alcohol consumption such as feeling a change in mood, being more relaxed and change in behaviour. But have you ever considered what might be going on in the body to make these effects?

Very little alcohol diffuses into the fat as fat has a very low solubility due to it having little water.

Alcohol diffuses fastest into the organs such as the heart, brain, and lungs which have a high blood supply that maintains a steep

First let’s look at how alcohol is made. The alcohol that is used in drinks for consumption purposes is ethanol, which is produced through a process of fermentation. To begin, sugar or starch is dissolved in water and yeast is added. This mixture is then fermented anaerobically (without presence of oxygen) at a temperature between 30-35°C. The environment in the last step forces the yeast to respire anaerobically which uses up the glucose (in the sugar), and produces ethanol and carbon dioxide [1](as shown in Fig1).

concentration gradient for maximum rate of diffusion.

The behavioural effects of alcohol can be explained by how alcohol affects the neurotransmitters (‘messengers’) in the brain.

When you consume alcohol, the amount of GABA (a neurotransmitter that dampens your responses) increases. As a result there's a reduction in communication in your brain cells you experience a decrease in your judgement and decision making, motor and visual responses are also slowed down.

As seen in the formula of ethanol in the photo, ethanol has an -OH (hydroxy) group which allows ethanol to have the ability of hydrogen bonding. Hydrogen bonding is an intermolecular force found between molecules.

This is why ethanol is soluble in water, as water molecules are also able to make hydrogen bonds allowing for hydrogen bonds to form between ethanol molecules and water molecules(Fig2). Ethanol’s solubility means that it can easily be absorbed into the

The liver uses an enzyme called alcohol dehydrogenase to convert alcohol into a toxic substance called acetaldehyde which is easier to break down and helps with removing alcohol from your system. Acetaldehyde is then broken down by the enzyme aldehyde dehydrogenase into acetate. Acetate is then further metabolised and eventually leaves the body as water and carbon dioxide. This often does not occur at the site of the liver, and rather is 20

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metabolised in the heart, skeletal muscle and brain cells.

Consuming food, especially carbohydrates, before drinking alcohol strongly affects how much the alcohol will physically affect you. By eating food, this lines the stomach and prevents the alcohol from rushing straight into the bloodstream. This then means the alcohol is released more slowly from the intestine, which gives the liver more time to break down the alcohol resulting in less alcohol circulating the blood stream and a weekend effect.

However, drinking fizzy alcohol increases the pressure in your stomach which forces alcohol into your bloodstream faster.

By Grace Kaprielian

Sources used: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC54 3875/ https://www.bbc.com/news/newsbeat-30350860

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How iodine in desert dust destroys ozone

(World AtlasThe Four Spheres Of The Earth WorldAtlas)

The iodine cycle is a biogeochemical cycle (a flow of chemical elements between living organisms and the environment) that primarily consists of natural and biological processes that exchange iodine through the lithosphere, hydrosphere, and atmosphere, in both oceanic and terrestrial transport processes . It can be found naturally in air, water and soil. The most important sources of natural iodine are the oceans. Iodine can also be found in the human body, and is mostly concentrated in the thyroid gland (a gland in the neck that produces hormones).

Ozone is a gas composed of three atoms of oxygen. It occurs both in the Earth's upper atmosphere and at ground level. Ozone can be good or bad, depending on where it is found.

At ground level, ozone is a harmful air pollutant because of its effects on people and the environment, and it is the main component in “smog”. In the atmosphere, ozone is very beneficial as it absorbs a lot of harmful UV radiation.

Atmospheric researchers have been interested in the idea that dusty layers of air have very little ozone. Speculations surrounded that some kind of dust-surface chemistry was eating up ozone, but no one had been able to show that happening in laboratory experiments.

Recent studies, led by the University of Colorado, in Boulder, shows that iodine in desert dust can decrease ozone air pollution but can prolong the lifetimes of greenhouse gas. The team made precise atmospheric measurements from aircraft of iodine monoxide ions inside dust layers from the Atacama and Sechura deserts in Chile and Peru, and were 22

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led by Rainer Volkamer, a professor of chemistry at UC Boulder.

https://www.atsdr.cdc.gov/toxprofiles/tp158-c6. pdf

In the study, researchers concluded that the data from the Tropical Ocean Troposphere Exchange of Reactive Halogens and Oxygenated Hydrocarbons (TORERO) field campaign (a study on the release, transport and fate of reactive halogen gases and their effect on the atmosphere) captured the three characters (iodine, dust and ozone) together, finally, in one image and it was clear that where desert dust contained significant levels of iodine, like dust from the Atacama and Sechura deserts, the iodine was quickly transformed (by a mechanism still not known) into a gaseous form and ozone dropped to very low levels.

https://beta.nsf.gov/news/iodine-desert-dust-de stroys-ozone

What we can take from this is that to avoid global warming, from a lack of ozone in the atmosphere, and climate change passing unchangeable levels, we must avoid adding anthropogenic (caused from human activity) iodine into the stratosphere such as through nuclear weapons testing or burning fossil fuels and waste.

By Sofia Waring Sources: https://www.sciencedaily.com/releases/2021/12 /211222153149.htm 23

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you happier and more alert due to the presence of certain chemicals.

There are 8 main steps involved in the production of chocolate which lead to its final form. The first step is fermentation, which is the process by which sugars are broken down anaerobically (without oxygen present) by microorganismsCacao seeds are the main ingredient in chocolate and grow on trees. The seeds are surrounded by a pulp which is the first step to make chocolate. The pulp is made up of water, acid and sugars such as glucose. Microorganisms remove the pulp from the bean through different methods. Three microorganisms which are involved are yeast, pulp enzymes and lactic-acid-producing bacteria. The sugars in the pulp are broken down and some of the products are carbon dioxide, ethanol, lactic acid and energy. The low pH, due to the acidic compounds, results in the cell wall of the bean to break down and the separated substances can then mix.

The second step in the production of chocolate is roasting the beans. The beans are cleaned after fermentation and then roasted.

This involves flavour precursors to be converted into compounds such as esters and aldehydes (organic compounds with Carbon).

These are responsible for the flavour and aroma of chocolate. After roasting, winnowing occurs which is where the shells of the bean are removed by a winnowing machine. This reveals the cacao nibs which are used to form cocoa liquor. Further processes can involve the conversion of the liquor into cocoa butter or cocoa solids. Next up, is the process of blending together the liquor and different amounts of cocoa butter. Chocolate comes in many different varieties of strength and cocoa butter is added in different amounts to create these different types. Once the strength of chocolate is determined, refining occurs. This is where the sugar and cocoa is broken down

The Chemistry of Chocolate: From Bean To Bar Chocolate is a delicious indulgence which is loved on a global scale. Its variable form means that there is a type of chocolate for everyone to enjoy from a simple bar of milk chocolate to dark, mint chocolate. Despite its large consumption many are unaware of the many processes involved in its production,with their knowledge limited to the fact that chocolate comes from cocoa seeds. These seeds are in fact processed to produce cocoa liquor, butter or solids and mixed with a sweetener such as condensed milk to produce the final chocolate product which can make 24

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into small particles which creates a smoother finish.

Anandamide is found in small quantities in chocolate alongside the natural production in the brain. It stimulates and opens synapses in the brain which allow feel good waves to travel more readily.

The process of tempering is the sixth step involved in chocolate production and consists of varying the temperature at which chocolate is cooled. Cocoa butter contains multiple types of fatty acids which separate in liquid form.

Tempering causes these fatty acids to mix together to create one solid form. There are 6 different forms of chocolate crystals (structures), also known as polymorphs, which have different melting temperatures. The one considered perfect has a 34 degree melting temperature and the chocolate is glossy, smooth, firm and melts in the mouth. After this, dutching occurs which is the chemical process of alkalizing cocoa solids to make them less bitter and acidic. Lastly, the chocolate is packaged which is done for more important reasons than just to be aesthetically pleasing.

It stops the chocolate coming into contact with the heat or humidity which can result in sugar bloom and fat bloom.

Flavour precursor - breaks down or reacts with other components to produce flavour, doesn’t actually contain any flavour itself Sugar bloom - white surface on chocolate caused by the sugar absorbing moisture, dissolving and then evaporating to crystallise Fat bloom - grey coating on chocolate caused by small globules of cocoa butter forming larger ones

By Dillan Rosen

So now we are aware of the multiple steps involved in chocolate production, let's take a look at some of the chemicals in chocolate, including tryptophan, phenylethylamine and anandamide, and their effect on the human body.

Tryptophan is an amino acid found in chocolate which is linked to the production of serotonin.

Serotonin is a chemical that nerve cells produce to communicate in the brain and is known as the happy hormone. The increase in serotonin after consuming chocolate, due to tryptophan, can explain feelings of happiness after eating it.

Phenylethylamine is a chemical which is released when we fall in love and increases the brain’s pleasure centres. It is present in small quantities in chocolate and can cause the aphrodisiac effect.

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