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Science Today Issue #1

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Bibliography "Atomic Structure." Shodor: A National Resource for Computational Science Education. Shodor, 6 Oct. 2002. Web. 12 Dec. 2011. <http://www.shodor.org/unchem/basic/atom/index.html>. "Atomic radius - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 12 Dec. 2011. <http://en.wikipedia.org/wiki/Atomic_radius>. "Chemistry Resources: The Elements: Noble Gases." Chemistry Resources. N.p., n.d. Web. 12 Dec. 2011. <http://www.chemtopics.com/elements/noble/noble.htm>. "Electronegativity - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 12 Dec. 2011. <http://en.wikipedia.org/wiki/Electronegativity>. "Ionization energy - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 12 Dec. 2011. <http://en.wikipedia.org/wiki/Ionization_energy>. "Other Periodic Table Trends | Chemistry | Khan Academy." Khan Academy. N.p., n.d. Web. 12 Dec. 2011. <http://www.khanacademy.org/video/other-periodictable-trends?playlist=Chemistry>. "Periodic Table Trends: Ionization Energy | Chemistry | Khan Academy."Khan Academy. N.p., n.d. Web. 12 Dec. 2011. <http://www.khanacademy.org/video/periodic-table-trends--ionizationenergy?playlist=Chemistry>. "Valence Electrons | Chemistry | Khan Academy." Khan Academy. N.p., n.d. Web. 12 Dec. 2011. <http://www.khanacademy.org/video/valenceelectrons?playlist=Chemistry>. "Visual Elements: Group 18 - The Noble Gases ." Royal Society of Chemistry | Advancing the Chemical Sciences. N.p., n.d. Web. 12 Dec. 2011. <http://www.rsc.org/chemsoc/visualelements/pages/data/intro_groupviii_data .html>. "Periodic Table Trends." Department of Chemistry at Texas A&M University. N.p., n.d. Web. 12 Dec. 2011. <http://www.chem.tamu.edu/class/ma

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http://www.daviddarling.info/encyclopedia/N/noble_gas.html A

http://chemistry.about.com/od/eleme ntgroups/tp/elementgroups.htm

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http://www.glogster.com/glog/6m nhlihjb969c354bmr45a0?old_em bed=True

http://periodictable.com/Elemen ts/018/index.html

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Editors

–Nikhil Purohit –Surya Suravaram

Mission

To share the facts and information about the Noble Gases obtained from online research and from studies. We want to spread the facts about the fabulous Noble Gases

In this Edition

– Brief Overview of the Gases – Periodic Table Trends – Physical Structure of Gases – State and Behavior of Gases – Electronegativity, Ionization Energies – Bonding – Valence Electrons – Games for Learning – Advertisements

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Meet The Noble Gases… Helium – Neon – – Group 18 of the Periodic Table – Also known as the “Inert Gases” – Non-Metals – Are Odorless, Colorless, and Monatomic

Argon – Krypton – Xenon – Radon –

Why Are They Special? – – – – –

Valence Electrons Atomic Radius Ionization Energy Low Reactivity Low Melting and Boiling Points

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“The Noble 6” “He” – Helium Atomic Structure 0

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Atomic Number: 2

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Average Atomic Mass: 4.0026

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Lewis Structure

In a neutral element of Helium there are: Electron 2 Protons Configuration: 2 Neutrons 1s2 2 Electrons State of matter at 25˚ C: Gas Melting Point: –272.2˚ C Boiling Point: –268.9˚ C

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“The Noble 6” “Ne” – Neon Atomic Structure -

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Atomic Number: 10

Average Atomic 0 = Neutron Mass: 20.180

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In a neutral element of Neon there are: 10 Protons 10 Neutrons 10 Electrons Electron Configuration: 1s22s22p6 State of matter at 25˚ C: Gas Melting Point: –248.7˚ C Boiling Point: –246.1˚ C

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Atomic Mass Many elements consist of more than one naturally occurring isotope. Therefore, individual isotopes will vary from an average atom of the element. That is why we calculate the average atomic mass of an element, which is the "weighted" average. This means that more "weight" or importance is given to the isotope which is in greater natural abundance. So, if we know the percentage of each isotope within an element we can easily find the average atomic mass by following the procedures below: 1. Find the percent of each isotope and the atomic mass of each of those. 2. Express the percentage as its corresponding decimal fraction. 3.Then just plug into the following formula: Average atomic mass = (fraction1 x atomic mass1) + (fraction2 x atomic mass2) + (fraction3 x atomic mass3) … and so on to find average atomic mass. 4. Now you have the average atomic mass of whatever element you have chosen. Example 1: Calculate the Average Atomic Mass of Neon Step 1. Find the percent of each isotope and the atomic mass of each of those. – Well, just use the Internet or a resource with that information. If you do that then you should get that Neon is made up of 20Ne (90.48%), 21Ne (0.27%) and 22Ne (9.25%). The numbers in front of the element just represent the ionic mass of the isotope. However the actual isotopic masses are 20Ne(19.9924u), 21Ne(20.9938u), 22Ne(21.9913). So now you are ready for step two. Step 2. Express the percentage as its corresponding decimal fraction. – Now you just divide everything by a hundred since they are percent’s to find the decimal fraction. 20Ne (90.48%) = 20Ne (0.9848) 21Ne (0.27%) = 21Ne (0.0027) 22Ne (9.25%) = 22Ne (0.095) Step 3. Now just plug into the following formula: Average atomic mass = (fraction1 x atomic mass1) + (fraction2 x atomic mass2) + (fraction3 x atomic mass3) … and so on to find the total mass of all the averages combined. – Average atomic mass = (0.9048 x 19.9924)+(0.0027 x 20.9938)+(0.0925 x 21.9913) After simplifying, the answer will be approximately 20.180. Step 4. Now you have the average atomic mass of Neon. – Now, since you got 20.180 for your average atomic mass, all you must do is to put units on there. The units for average atomic mass is amu (atomic mass units) so your answer would be that the average atomic mass for Neon is 20.180 amu.

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Atomic Mass Example 2: Calculate the Average Atomic Mass of Argon Step 1. Find the percent of each isotope and the atomic mass of each of those. – Again, just use the Internet or a resource with that information. If you do that then you should get that Argon is made up of 40Ar (99.6%), 36Ar (0.34%), and 38Ar (0.06%). The actual isotopic masses are 40Ar (39.9624u), 36Ar (35.9675u), and 38Ar (37.9627u). Step 2. Express the percentage as its corresponding decimal fraction. – Now you just divide everything by a hundred since they are percent’s to find the decimal fraction. 40Ar (99.6%) = 40Ar (0.996) 36Ar (0.34%) = 36Ar (0.0034) 38Ar (0.06%) = 38Ar (0.0006) Step 3. Now just plug into the following formula: Average atomic mass = (fraction1 x atomic mass1) + (fraction2 x atomic mass2) + (fraction3 x atomic mass3) … and so on to find the total mass of all the averages combined. – Average atomic mass = (0.996 x 39.9624)+(0.0034 x 35.9675)+(0.0006 x 37.9627) After simplifying, the answer will be approximately 39.948. Step 4. Now you have the average atomic mass of Argon. – Now, since you got 20.180 for your average atomic mass, all you must do is to put units on there. The units for average atomic mass is amu (atomic mass units) so your answer would be that the average atomic mass for Argon is 39.948 amu.

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“The Noble 6” “Ar” – Argon Atomic Structure -

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Lewis Structure

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In a neutral - element of Argon there are: 18 Protons 22 Neutrons 18 Electrons

Atomic - Number: 18 Average Atomic Mass: 39.948 Electron Configuration: 2 2 6 2 6 1s 2s 2p 3s 3p Melting Point: –189.4˚ C State of matter Boiling Point: at 25˚ C: Gas –185.9˚ C -

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“The Noble 6” “Kr” – Krypton Atomic Structure -

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In a neutral - element of Krypton there are: 36 Protons - - - 48 Neutrons 36 Electrons - Atomic Number: 36 - Average Atomic - Mass: 83.80 Electron Configuration: [Ar]3d104s24p6

Melting Point: –156.6˚ C Boiling Point: –152.3˚ C

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State of matter at 25˚ C: Gas

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“The Noble 6” “Xe” – Xenon Atomic Structure -

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In a neutral - - - element of Xenon there are: 54 Protons - - - 77 Neutrons 54 Electrons - - Atomic - Number: 54 Electron Configuration: [Kr]4d105s25p6 State of matter Lewis Structure at 25˚ C: Gas Melting Point: -

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–111.9˚ C Boiling Point: –107˚ C Science Today© 2011

Average Atomic Mass: 131.29 12


“The Noble 6” “Rn” – Radon Atomic Structure -

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= Proton (+)

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In a neutral element of Radon there are: 86 Protons 136 Neutrons - - - -86 Electrons Atomic - - Number: 86 Average Atomic Mass: [222] -Electron Configuration: [Xe]4f145d106s26p6 -

Melting Point: Structure –71˚ C Boiling Point: –61.8˚ C -

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State of matter at 25˚ C: Gas

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Determining Stable Atom Structures 0

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Step 1. Color the correct amount of protons in the atom by looking at how many neutrons and protons there are Step 2. Do the same for the neutrons Step 3. Check if youâ&#x20AC;&#x2122;re atom is stable

What element does this structure represent? Answer: Neon Science TodayŠ 2011

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The New  Way  to   Fly  

http://meetinthelobby.com/up-­‐balloons-­‐hit-­‐the-­‐boston-­‐

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Electrons Increase

Protons & Electrons

Electrons Increase

Wikipedia® – The number of valence electrons

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“The Noble 6 and the Octet Rule” The reason why the Noble Gases are on Group 18, and are on the right end of the periodic table is because of their electron shells. All of the Noble Gases have their electron shells filled, and have 8 electrons on their most outer shell, which means that they have 8 valence electrons–in their highest most stable state. Thus, all of the Noble Gases meet the Octet Rule, which states that atoms of low atomic number tend to combine in such a way that they each have 8 valence electrons in their outer shell. Many elements want to get 8 electrons Helium Atom in their outer shells, and because of that it Electron gives them a higher reactivity because they –– Two Full Electron Shell need those electrons so they create bonds with other atoms which range from covalent, ionic and metallic just so they can be like the special “Noble Gases”.

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Bonding

http://www.accessexcellence.org/RC/VL/GG/ecb/covalent_ionic_bo nds.php

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How to be like a Noble Gas! Most of the elements in the Periodic Table want to be like the Noble Gases with 8 electrons in their outer shell, so in order to get those electrons they need elements bond with each other and create either a covalent, ionic or metallic bond in order to pretend to be like a Noble Gas. This is one of the reasons why the Noble Gases are so special, because everyone wants to be like them–they’re like celebrities. A covalent bond forms when two elements bond in a way that they share electrons to fill their energy shells. So for example, we can take Hydrogen here who has 1 valence electron and bond it with another Hydrogen atom so that both Hydrogen atoms can fill their shells and pretend to be like the Noble Gas, Helium who has 2 valence electrons. This creates a H2 molecule and this molecule happens to be “non-polar”, which means that one atom doesn’t attract the electrons more than the other because of the electronegativity of Hydrogen. But a “polar” molecule in this sense would be something like Science Today© 2011

Water or H2O where Oxygen has a higher electronegativity than Hydrogen so the electrons are around Oxygen more. But ionic bonds, are when an element from the left side of the periodic table (a metal) is put with an element from the right (a non metal) for example. They will react in such a way that the non-metal will take the electron from the metal, instead of sharing it. The metal would want to lose an electron because it only has a few valence electrons, so for example Lithium would give an electron away so it can go down an orbital and be like Helium, which has a full electron shell. While the non-metal, like Fluorine would want to take since it is close to filling its outer orbital so it can be like Neon.

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Calculated Atomic Radii Measured in picometres (pm)

Radii Increases

Noble Gases

Wikipedia®

Radii Decreases

– Calculated Atomic Radii: http://en.wikipedia.org/wiki/Atomic_radius

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“The Atomic Radius Trend” Radon has a much larger atomic radius and electron cloud of 120 pm compared to any other Noble Gas, while it’s electron shell is filled. Generally, the more electrons an element has, makes the element smaller as the electrons are close together. We can see that this trend applies across the entire periodic table–as you move down, the electrons get further away from the nucleus. We

+1 Energy Level

Smallest Radii *Electrons are close together

Largest Radii

Science Today© 2011

can see this because of the fact that as you move down each period the energy level increases by +1 so for example Xenon is at the 5 energy level, but Radon is at a even higher energy level at 6. Furthermore, the energy level is higher to hold the 86 electrons in the atom because its atomic number is 86. Now that we know this, we can clearly see that Krypton has a smaller electron cloud than Xenon, then Argon, Neon and finally Helium with the smallest cloud. Looking back at the rest of the table, for each period, the Noble Gases have the smallest electron cloud because its electron shells are full and the electrons can fit closely together near the Nucleus.

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Electronegativities of the Elements Using the Pauling Scale

Noble Gases

Wikipedia®

– Electronegativities of the elements: http://en.wikipedia.org/wiki/Electronegativities

Ionization Energies

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Atomic Radius, Ionization and Electronegativities in One Bundle! Now you may wonder why Krypton, Xenon and Radon have electronegativities although their electron shells are completely filled which would mean that the atom doesn’t need to get or give any electrons from bonding. Since we know that atoms bond in order to fill their electron shells by sharing, giving or taking electrons we can observe that obviously every element wants to be like the Noble Gases, as they are envious of them because of their full shells. Only Helium, Neon and Argon don’t want to react with any other elements, only if there is high ionization energy used. So applying the previous trend we learned about Atomic Radius, we know that moving across the periodic table decreases the atomic radius and moving down increases the radius therefore since the electron clouds of Krypton, Xenon and Radon are bigger it means that it is easier to remove the electrons from them since there is more room. So, increasing the atomic radius decreases the amount of Ionization energy required to take the electron from the atom. Now with that, we can Science Today© 2011

Not Very Bondable – Very Low Electronegativity – Very High Ionization Energy

Bondable – High Electronegativity – Low Ionization Energy

take one more step and realize that with a lower ionization energy to take an electron from an atom increases the electronegativity of the atom since it can bond with other atoms more easily. Krypton, Xenon and Radon are more ‘generous’ to other elements in this sense because they are willing to share or give electrons more easily than the ‘selfish’ Helium, Neon and Argon. 23


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The Ions and the Ionic Radii Trend

Science TodayŠ 2011

ions are smaller than their uncharged and neutral atoms, and negative ions are larger than their atoms. Therefore, the ionic radii (the radius of an ion) will increase as there are more negative ions, and also obviously get larger as you go down a group since there are more electrons that create a larger atom. Since the Noble Gases rarely form ions, their ionic radii just increases as you go down the group since there are more and more electrons in every orbital. http://bookbuilder.cast.org/ view_print.php?book=37167

As many of you may know, an additional orbital is being added as you move down the periodic table. Therefore, as you move down Group 18, the number of electrons in each Noble Gas increases. This naturally causes the ionic radius to increase as you move down the periodic table. This all relates back to how ions form, only through ionic bonds mentioned in the â&#x20AC;&#x153;How to be a Noble Gas!â&#x20AC;? article. But when these elements gain or lose electrons they will gain a negative or a positive charge. The element that loses an electron would gain a positive charge since it has one less electron while the element that gains an electron will have a negative charge since it has more electrons than protons. Since they are losing and gaining electrons, these ions, atoms with a charge, will be a different size than the neutral atom. Positive

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The Noble Gases

Across 1. The element with an atomic number of 10 3. The typical distance from the nucleus to the boundary of the surrounding cloud of electrons in an atom. 5. The Noble Gas with six outer energy levels 6. The element with the electron configuration of [Kr]4d105s2 5p6 7. The number of electrons in every Noble Gas besides Helium 8. The third element in the Noble Gases family 9. The number of orbitals in Helium 10. An atom with a positive or negative charge 11. An element commonly used in balloons. Down 2. The tendency for one atom to attract electrons to itself 4. The Noble Gas with an atomic weight of 83.80 Science TodayŠ 2011

Answers: 1. NEON 2. ELECTRONEGATIVITY 3. ATOMICRADIUS 4. KRYPTON 5. RADON 6. XENON 7. EIGHT 8. ARGON 9. ONE 10. ION 11. HELIUM

Crossword Puzzle

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The Noble Gases  

A Magazine describing the various features, facts and information about the Noble Gases as well as other information about the Periodic Tabl...