PLaNCK! - 08_Anteprima ENG

P La N K C

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ISSN 2284-0761 ISBN 978 88 6787 560 3

Poste Italiane SPA - Spedizione in abbonamento € 20,00 - copia singola € 7,00 Autorizzazione del Tribunale di Padova numero 4093 del 21 novembre 2013 ISSN 2284-0761 - ISBN 978 88 6787 560 3 - Quadrimestrale - Numero 08 - Maggio 2016

I’m going to be

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ck lan

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a little scie ntist!

A WORLD OF MOLECULES A LOT OF EXPERIMENTS!

CIBO LABORATORIO FROM THE HAIR TONIC TO THE HOT ICE E CERVELLO DI CUCINA p. 2430 e 36 pag.

pag. 22

THE ADVENTURES OF MARIE AND MAX p. 5 WHAT A SMELL! p. 26 THE MOLECULES OF LIFE p. 34

What’s

inside!

Features 10 From the encounter... a molecule is born!

Let’s discover the chemical bonds!

12 Everything is transformed

The secrets of chemical reactions

14 Molecular... geometry Do molecules have a shape?

16 Let’s meet... Antoine-Laurent Lavoisier 17 Let’s meet... Linus Pauling 18 A very special molecule The incredible properties of water

22 A matter of state 26 What a smell!

The molecules of off-odours

29 Natural... like chemistry!

30 Molecular... trains

The synthesis of peptides at the Department of Chemical Sciences of University of Padova

32 Carbon, organic molecules and more stories 34 What are we made of?

EDITORIAL An atom of this, two atoms of that, an atom of something else... et voilà, here is a molecule! Dear friends of PLaNCK!, our adventure to explore the galaxy continues! In the last issue of our magazine we have known the atoms, the small bricks that form everything in the universe.

In this issue, the travel continues to discover what happens when more atoms bond each other to form molecules. We will find that with few atoms some fundamental molecules for our life could be obtained: for example, with only two atoms of hydrogen and one atom of oxygen the water molecule is obtained! And it is from water that life on Earth has been developed... but not so fast, for the moment have fun combining two, three, and more atoms together and... let’s see what happens!

The molecules of life

Departments 5 PLanck on the run!

Episode 2: A mystery among molecules

20 The cleaning power of soap 24 Little chemists 1. Coloured hair tonic!

How to make a hair tonic at home

28 36 38 39

The right molecule!

Little chemists 2. The hot... ice!

Read science!

Glossary

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PLaNCK! is a project by Accatagliato association via S. Sofia 5 - 35121 Padova accatagliatoassociazione.wordpress.com accatagliato.info@gmail.com Printing press and editor CLEUP sc “Coop. Libraria Editrice Università di Padova” via Belzoni 118/3 - 35121 Padova tel. 049 8753496 www.cleup.it - www.facebook.com/cleup ISSN 2284-0761 ISBN 978 88 6787 560 3

www.planck-magazine.it redazione@planck-magazine.it © 2015 by Accatagliato All Rights Reserved

Scientific Committee

Department of Physics and Astronomy Prof. Alberto Carnera Dr. Stefano Ciroi Prof. Ornella Pantano Prof. Giulio Peruzzi Prof. Cinzia Sada Department of Chemical Sciences Dr. Massimo Bellanda Dr. Laura Orian Dr. Giacomo Saielli Dr. Elisabetta Schievano

Editorial Board

Project coordinators: Agnese Sonato e Marta Carli Editor-in-chief: Andrea Frison Managing editor: Marta Carli Editorial secretary: Serena Maule Writers: Marta Carli, Marco Maggioni, Agnese Sonato, e Andrea Frison English version: Nadia Andrea Andreani, Marta Carli, Agnese Sonato.

Proofreaders: Petra Spataro, Comic strip: Bianca Maria Scotton (Graphics), e Gianluca Pozza (plot) Graphics: Bianca Maria Scotton Graphic project: Stefano Pozza Photography: Agnese Sonato, photographic archive 123RF

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N W O D E L A C S , P U E L A SC

from the largest to g, hin yt er ev .. of e siz al pic ty e Here you can find th . the smallest things in the world ue?

On which step are we in this iss

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r a l u c e Mol y r e t s i M

Planck on ! the RUN 2 Episode

In the previous episode Planck, the monkey, disappeared with the new special glasses for exploring the microscopic world. Max and Marie looked for it among the atoms, without results.

Will they find Planck in the molecular world?

Where is Granma?

Let’s call her!

What a mess!

Guys, my personal glasses disappeared! I can’t reach you...

How many molecules!

How can we find Planck?

. . . r e t n u o c n e e h t From E L U C E L A MO !

N R O B IS rdivo

By Martina Ta

What happens when the atoms come together?

Like a group of friends that hold hands and form a chain, more atoms together form a molecule, creating chemical bonds between them. To do this, they exploit their valence electrons... do you remember them? They are the most external electrons in the atom!

But what happens exactly? Two atoms that are close each other can share a certain number of valence electrons. After that, the shared valence electrons do not rotate anymore around the nucleus of one single atom, but around both nuclei.

We can imagine this sharing as the “glue� that holds together the atoms.

The strength of this union is not always the same, but it depends on the type of involved atoms; some bonds are stronger, others are weaker. Furthermore, different atoms do not have the same aptitude to form bonds. In 1852 Edward Frankland remarked that each atom has a specific capability of combination: in fact, there are atoms that form just one bond, such as hydrogen, while others - for example carbon –can even form four bonds.

Atom by atom, bond after bond, we can obtain very simple molecules, like the oxygen molecule (only two atoms of oxygen), or very complex molecules like proteins.

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d e m r fo s n a tr is g in th Every actions The secrets of chemical re What do these two things have in common: an explosion and the milk becomes acid after the expiration date?

The answer is simple: both are chemical reactions!

A chemical reaction occurs when two or more molecules interact and, as a result, they transform into different molecules.

The initial molecules are the reagents, whereas the final molecules are the products of the reaction. In a chemical reaction, the atoms cannot appear or disappear, but only move from one molecule to another. , molecules t n e r e f if d ion! u combine ical react m e h c When yo a t simply always ge olecules m you don’t e h t for cases happens, is h T In some . g ter. ut reactin r in the wa a g u mix witho s t u p when we example,

In photosynthesis, carbon dioxide and water are transformed into oxygen and glucose (a sugar).

In fireworks, gunpowder (a mixture of potassium nitrate, charcoal and sulfur) explodes reacting with a compound that contains oxygen.

To obtain the different colors, salts of different atoms are added to the mixture: for example, yellow is obtained with sodium salts, and blue is obtained with copper salts.

Rust is formed when iron reacts with oxygen and water.

Methane, the main component of cooking gas, reacts with oxygen in the air producing carbon dioxide and water vapor.

Molecular...

GEOMETRY

Each object has its own shape! The book is a parallelepiped, the ball is a sphere, the hat of a magician is a cone... and then there are the cylinder, the pyramid and so on.

But what about molecules? Do molecules have a shape? Of course they have!

The shape of molecules depends on how many bonding their atoms form and how many pairs of central atom electrons remain free, namely the electrons that are not occupied in the chemical bonds between the atoms.

One molecule, one geometry Atom legend:

Aluminum

Nitrogen

Calcium

Carbon

Hydrogen

Oxygen

E

CALCIUM HYDRIDE FORMULA: CaH2 NUMBER OF ATOMS: 3 NUMBER OF BONDS: 2 FREE-ELECTRON PAIRS: 0 GEOMETRY: LINEAR

METHANE FORMULA: CH4 NUMBER OF ATOMS: 5 NUMBER OF BONDS: 4 FREE-ELECTRON PAIRS: 0 GEOMETRY: TETRAHEDRON

ALUMINUM HYDRIDE FORMULA: AlH3 NUMBER OF ATOMS: 4 NUMBER OF BONDS: 3 FREE-ELECTRON PAIRS: 0 GEOMETRY: EQUILATERAL TRIANGLE

l a i c e p s y r e Av e l u c e mol er t a w f o s ie t r e rop p le ib d e r c in e Th

e tip. en atom on th g y x o e th h it ed, w ut 104°. cule is V-shap n bonds is abo e g ro d y -h n A water mole e g y een the two ox The angle betw

MY NAME IS... H-TWO-O!

Have you ever heard a chemist call water like this? Well, h-two-o (that is written H2O) it is the chemical formula for water. A water molecule is made by an oxygen atom and two hydrogen atoms.

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Water is one of the most important substances on Earth. The presence of liquid water makes out planet unique and full of life. Let’s give a closer look to this molecule!

ELECTRONS ARE CHOOSY!

The bond between oxygen and hydrogen in a water molecule is a polar covalent bond. It means that the electrons prefer to stay around oxygen rather than hydrogen.

Consequently, the oxygen atom is negatively charged, while the two hydrogen atoms are positively charged. This property makes water really special!

r e w o p g n i n a e The cl P A O of S Why do we need the soap for cleaning? If you try to clean dishes or dirty glasses just with water you cannot remove the dirt! Why?

WHO IS AFRAID OF WATER? In nature there are molecules soluble in water: hydrophilic molecules. Other molecules are not soluble in water and they are called hydrophobic. For example oil and fats, which are the components of the dirt, are formed by hydrophobic molecules and thus re not soluble in water. For this reason you can not take away the dirt with water!

WHAT DOE S IT MEAN?

“Hydrophilic ” means “frie nd of water”, “hydrophobic while ” means “afra id of water”.

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e t a t s f o r e t t A ma A drink, ice and lots of bubbles: this glass contains the three most common states of matter on Earth!

The drink is liquid... but it contains gas: the bubbles that make the drink fizzy are made of carbon dioxide in the gaseous state. In addition the ice cubes are just water in the solid state!

What determines the state of matter? We must summon the molecules!

In substances, the molecules can move in different ways.

In a solid, the molecules are arranged in a lattice highly ordered and they cannot move easily. For this reason, a solid always maintains approximately the same shape and the same volume.

In a liquid, the molecules are still held together by intermolecular forces, but they are free to move.

For this reason, a liquid can change shape passing from one vessel to another.

In a gas, the molecules are completely free to move: for this reason gas expands to fill the entire volume at its disposal.

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TS

EXPERIMEN

Difficult

COLOU

y level

D: YOU NEE

RED HA IR TON IC!

bbage of red ca s m a r g 0 50 – and knife ing board t t u C – 2 pots – – Sca tle le e t a n – Pes o b r a – Cor ium bic d o S n starch – e – ic

ju n o G m ly Le cerin – – Liquid talc – 500 gram s of water – Sug ar

INSTRUCTIONS First step: Let’s prepare the colourants!

1 2 3 4 5

By Fran cesco

Coghi

1

Finely slice the red cabbage.

Put the sliced cabbage in a pot and grind it.

2

Add water and boil for 30 minutes.

Recover the coloured water and pour equally into three small containers.

Squeeze a lemon, filter the juice, pour 20 grams in a clean small jar and then pour everything inside one of the three small jars you prepared with cabbage-filtered water.

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Pour 20 grams of water in a glass, add 2 teaspoons of bicarbonate and then pour all in the other small jar you prepared with the cabbage-filtered water.

Compare the colours obtained with the initial cabbage coloured water.

4

PAY ATTENTION Remember, always ask an adult to help you.

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WHAT !

L L E M S A Why something has a offodour? The responsibility is of certain molecules... let’s find out them!

Thiol

ic acid

Sulfur

The rotten egg The typical rotten egg odour is due to sulphide acid, formed by two hydrogen atoms and one sulfur atom. In general, several molecules containing sulfur smell. For example, molecules that contain, at the end, a sulfur atom bounded to hydrogen have a smell that resembles that rotten egg. These molecules are called thiols.

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IEV THE INTERW

An interview with MARTA DE ZOTTI

Molecular...

TRAINS

Marta and the peptide synthesis

Marta De Zotti, researcher at Department of Chemical Sciences of the University of Padua talks about her job.

Peptide synthesis? Marta, what does it mean?

“In chemistry, the word synthesis” explains Marta while she takes off her lab eyeglasses and puts in order her lab coat, “means to induce some chemical reactions with the aim to create a new chemical compound. For example, DNA or small proteins can be created in the lab!”.

In particular, what do you usually synthetize?

“I synthetize PEPTIDES, namely small proteins made of several amino acids bound each other. Basically, each peptide is just like a little train in which coaches are the amino acids. Usually a peptide has no more than 50 amino acids, but the ones I am studying have no more than 25 of them”

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Peptides and amino acids... How many new words! Can you tell us something more about these... molecular trains?

“Not many people knows that peptides are an important constituent of our defence system.

For example, some are in the skin and allow killing bacteria before they can access our body. I deal with peptide synthesis to fight against bacteria or tumours by attacking only ill cells and not the healthy ones, and then I study their three-dimensional structure and how they organize in the space, that’s really important!”

Can you explain this better?

“Of course! Every amino acid has a specific function and to do it, it has to be in the right position. If this position changes the peptide does not work at all or it works less than before, as a train! If you put the coach with the coal next to the steam locomotive, it is more effective in comparison with to put it at the end of the train! Starting from the peptides that already exist in nature, I try to discover how they act and then “I mix the coaches”: I create new peptides that are more effective than the natural ones.”

Carbon,

organic molecules and more stories Hands, eyes and heart are different parts of our body, but they are all made of cells, and cells are made of small molecules.

All living organisms are made of molecules: just think that a bacterium contains 5000 different types of molecules!

We call “organic molecules” almost all the molecules that contain at least one carbon atom and all the organisms are mainly formed by these molecules.

There are four types of molecules that we find in all organisms • Sugars (or carbohydrates) that are sources of energy.

• Lipids (or fats) that form the body structure and store energy.

• Proteins that form the body structure and allow chemical reactions.

• Nucleotides that are the components of DNA and RNA. All of these molecules contain carbon, hydrogen and oxygen atoms. Proteins also contain nitrogen and sulfur, while the nucleotides and some types of lipids contain nitrogen and phosphorus.

But why is CARBON, and not another atom, composing the organic molecules? Carbon has special properties that allow it to build real scaffolding on which different type of atoms (such as hydrogen and oxygen) can be bound.

In fact, a carbon atom can form bonds with up to four different atoms, some of which can be... other carbon atoms!

This ability to form a network of atoms allows the creation of many structures, both two- and threedimensional.

Also two carbon atoms can be bound together forming double bonds, or even triple!

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DO YOU KNOW THAT...

Quasi tutte le mol ecole Almost all molecules that contain carbon atoms are organi c molecules.

However, there ar e some very common molecules that contain carbon and are no t considered organic, because they are not part of the struct ure of living organisms, for example the calcium carbonat e (limestone) and carbon dioxid e (CO2).

What are we made of?

The molecules of life Everything around you is made of atoms and molecules, but... what are you made of? The answer is: “BIOmolecules”!

Just like you, your friends, your pets, all the plants and the tiny insects that live in your garden… they are all made of biomolecules. What do all these things have in common? That’s easy: they are living beings! Indeed: all living beings on Earth are made of biomolecules.

rived The word “bio” is de means from a Greek word that e then “life.” Biomolecules ar “the molecules of life”.

Biomolecules contain mainly carbon and hydrogen atoms, but also nitrogen, oxygen, phosphorus and sulfur. These atoms build up small molecules, and these molecules joined together build up the biomolecules.

So, biomolecules are very large molecules made up of smaller molecules!

Biomolecules contain many atoms.

Therefore, it is very difficult to draw them using a formula. However, we can recognize the different types of biomolecules by their structure!

SUGARS or CARBOHYDRATES They can have three different forms. Monosaccharides are the simplest type of sugars: they are constituted by a single molecule. Disaccharides are formed by two monosaccharides.

Polysaccharides are composed of many monosaccharides, joined together like a chain.

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y level

THE HO T... ICE !

D: YOU NEE –

– – – – – –

te bicarbona m iu d o s of 84 grams s) blespoon a t 3 t u gar o (ab wine vine e it h w f o 1 liter g gas the cookin a pot a glass spoon a wooden ! un adulto L’aiuto di

PAY ATTENTION Remember, always ask an adult to help you.

INSTRUCTIONS

1 2

Put the sodium bicarbonatein a pot.

3 4 5 6

Continue stirring until the solution stops making foam and becomes transparent.

Add all the white wine vinegar, do it slowly to avoid splashing and stir constantly. You’ll see the foam formation in the pot: this is the sign that a chemical reaction is taking place!

Heat the solution until boiling (remember to keep the windows open because there is a strong smell of vinegar!).

During the boiling you can see that crystals will form on the sides of the pot. Take some crystals aside!

1

2

When a yellow (or light brown) liquid film will be formed, move the concentrated solution in a glass. It is important not to form a rigid film over the solution, otherwise the experiment will not work!

3

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5

6

CE! READ SCIEN

Molecules: The Elements and the

Architecture of Everything

by Theodore Gray Nick Mann Photographer Black Dog & Leventhal

A review by Pamela Pergolini In “Molecules: The Elements and the Architecture of Everything” (Black Dog & Leventhal, 2014), his sequel to “The Elements”, Theodore Gray demonstrates how in daily life we encounter vastly more molecules and compounds than elements of the periodic table because atoms can connect to each other in so many different ways. But what holds these atoms together with such great diversity?

But especially what is difference between compounds and molecules?

Through the gorgeous photographs of Nick Mann, as well as diagrams of the compounds and their chemical bonds, the author explore the rooms’ house of chemistry, organic and inorganic, and the vast array of materials that molecules can create (soaps, solvents, goops, oils, rocks, ores, ropes, fibers, drugs, sweeteners, perfumes, colors and so on).

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Molecules: The Elements and the Architecture of Everything

by Theodore Gray

SCIENCE !

H S I L G N E IN

Afraid = impaurito Arrow = freccia Bond = legame Brick = mattone Cabbage = cavolo Charcoal = carbone vegetale Coache = vagone. Attenzione:

vuol dire anche allenatore Cornstarch = amid di mais Dioxide = biossido Drug = farmaco Encounter = incontro Expiration date = data di scadenza Fat = grasso Foam = schiuma Hair tonic = gel per capelli Health = salute Healthy = salutare, che fa bene alla salute Heat = calore Limestone = calcare Man-made = fatto dall’uomo Matter = materia Modelling clay = pasta modellabile Necklace = collana Odour = odore Phase = fase Preservative = conservante Shape = forma Smell = puzza Soap = sapone State = stato To boil = bollire Train = treno Varnish = vernice Vinegar = aceto Amine = ammina Water = acqua Carbohydrate = carboidrato Wine = vino Carboxyl acid = acido carbossilico Lipid = lipide Nucleic acid = acido nucleico Nucleotide = nucleotide Peptide = peptide Protein = proteina Sugar = zucchero Thiol = tiolo

The molecular glossary!