1. Trends in the periodic table:
Ionization Energy Atomic Radius Electron Affinity Electronegativity

2. Background
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Electrons can jump between shells (Bohr’s model supported by line spectra)
The electrons can be pushed so far that they escape the attraction of the nucleus
Losing an electron is called ionization
An ion is an atom that has either a net positive or net negative charge
Q: what would the charge be on an atom that lost an electron? Gained two electrons?
A: +1 (because your losing a -ve electron)
A: -2 (because you gain 2 -ve electrons)

3. Ionization energy
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Ionization energy is the energy required to remove one outer electron from an atom
We will be examining the trends in ionization energy in groups and periods
Handout
Note: atomic radius is the distance from the nucleus to the outer electron shell
Follow directions on sheet and answer questions (you can use textbook for help)
Ignore H when looking at trends, look at many periods/groups when summarizing trends

4. Periodic table trends Answers

5. Ionization energy vs. atomic number
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6. Atomic radius vs. atomic number
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7. Answers 2 a) – He, Ne, Ar, Noble gases 2 b) – Li, Na, K, Alkali metals
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2 a) – He, Ne, Ar, Noble gases
2 b) – Li, Na, K, Alkali metals
3 a) – Li, Na, K, Alkali metals
3 b) – He, Ne, Ar, Noble gases
4. As one increases, the other decreases
5. Ionization energy increases
Atomic radius decreases
6. Ionization energy decreases
Atomic radius increases

8. electron configuration of Na+ resembles Ne
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11p+ 12n°
11p+ 12n°
10p+ 10n°
Na has 11 electrons
Na+ has 10 electrons
Ne has 10 electrons
electron configuration of Na+ resembles Ne
Alkali metals become like noble gases
Radius increases because shells are added
Increased radius will make it easier to lose an electron because of greater distance between positive and negative charges

9. Li (enc = 1) Be (enc = 2) B (enc = 3) + + + + + + + + + + + +
9. Proton # increases. More protons means greater attraction between nucleus and outer electron thus higher ionization energy.
The greater attraction also means that outer electrons are brought closer to the nucleus, thus smaller atomic radius results.
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Li (enc = 1)
Be (enc = 2)
B (enc = 3) + + + + + + + + + + + +

10. Noble gases are ignored
Electron affinity is energy associated with an atom gaining an electron. It is highest in the top right where atoms are smallest with the greatest number of protons
Electronegativity is a number that describes the relative ability of an atom (when bonded) to attract electrons. The trend is the same as affinity for the same reason
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11. Answers 2 a) – He, Ne, Ar (1), Noble gases (1)
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2 a) – He, Ne, Ar (1), Noble gases (1)
2 b) – Li, Na, K (1), Alkali metals (1)
3 a) – Li, Na, K, Alkali metals (1)
3 b) – He, Ne, Ar, Noble gases (1)
4. As one increases, the other decreases (1)
5. Ionization energy increases (1)
Atomic radius decreases (1)
6. Ionization energy decreases (1)
Atomic radius increases (1)
/11

12. Diagram of Na(1) & Na+(1), Na+ resembles Ne (1)
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11p+ 12n°
11p+ 12n°
10p+ 10n°
Na has 11 electrons
Na+ has 10 electrons
Ne has 10 electrons
Diagram of Na(1) & Na+(1), Na+ resembles Ne (1)
Alkali metals become like noble gases (1)
Radius increases because shells are added (1)
Increased radius will make it easier to lose an electron because of greater distance between positive and negative charges (1) /6

13. Li (enc = 1) Be (enc = 2) B (enc = 3) + + + + + + + + + + + +
9. Proton # increases (1). More protons means greater attraction between nucleus and outer electron (1) thus higher ionization energy.
The greater attraction also means that outer electrons are brought closer to the nucleus, thus smaller atomic radius results.
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Li (enc = 1)
Be (enc = 2)
B (enc = 3) + + + + + + + + + + + +

14. For more lessons, visit www.chalkbored.com
Noble gases are ignored (1)
Electron affinity is energy associated with an atom gaining an electron (1). It is highest in the top right (1) where atoms are smallest with the greatest number of protons
Electronegativity is a number that describes the relative ability of an atom (when bonded) to attract electrons (1). The trend is the same as affinity (1) for the same reason
9 – 10: /7
Total: /24
Note: graphs from day 1 were marked separately
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