1. Ions

2. Valence Shell Valence Shell: The most outer energy level.
1s22s22p63s23p3
1s 2s p s p

3. Stability
1s 2s p s p
1s 2s p s p

4. s p
Then, the next energy level down becomes the valence shell
s p
s p

5. Valence Electrons: Label on your PTE1 8 2 3 4 5 6 7

6. Group 1
s p
s p
New valence shell

7. Ions Ion: An atom that has lost or gained one or more electrons
Cation: An atom that has lost an electron
Positive Charge
Anion: An atom that has gained an electron
Negative Charge

8. - - + -

9. - - + - + + + + - -

10. - - + - + + - + + - - -

11. So, how do you figure out what ion an atom makes?
Look at the electron configuration.

12. Octet Rule
Octet Rule: All atoms lose and gain electrons to form a full valence shell
H, He = 2
All other elements = 8
“Oct” = 8

13. Ions formed by group - Add to your PTE1+ 1 8 2 2+ 3 3+ 4 3- 5 6 2- 1- 7
Gain e-
Lose e-
Anions
Cations

14. Set up a table: Element # Valence E- Loses or Gains E-
Cation or Anion?
Charge of Ion
Symbol of Ion
Name of Ion
14 lines… …

15. Number of Valence ElectronsLi Be B F O N Cl P K Ca Al Se Br Kr

16. Lost or Gained Electrons?Li Be B F O N Cl P K Ca Al Se Br Kr

17. What ion is formed? Li Be B F O N Cl P K Ca Al Se Br Kr

18. Anion or Cation? Cation is positive because it has LOST electrons.
It is a positive thing to have a cat, and it would be sad if you lost your cat.
Anion is negative because it has GAINED electrons
Mnemonic?

19. Anion or Cation? Li Be B F O N Cl P K Ca Al Se Br Kr

20. Symbols for Ions Element SymbolCharge Li+ Cl- Al3+ Number, then + or –
No need to write a “1”
1 is often invisible in chemistry

21. Write the Symbol Li Be B F O N Cl P K Ca Al Se Br Kr

22. Names for Ions Cations: Same name as the element Li+: lithium ion
Sr2+: strontium ion

23. Naming Ions Anions: Ending changes to “-ide” N3-: nitride ion
O2-: oxide ion
F-: fluoride ion
S2-: sulfide ion
Cl-: chloride ion
Br-: bromide ion
I-: iodide ion

24. Name the ions formed by these elementsLi Be B F O N Cl P K Ca Al Se Br Kr

25. How easy is it to make an ion?
Ionization Energy: The amount of energy required to remove an electron to form a positive (+1) ion.
Increases going UP a group and across a period to the RIGHT.

26. Ionization Energy Increases Ionization Energy Increases

27. Trends in Ionization Energy
Why?
The smaller the atom, the closer the valence shell is to the nucleus.
The closer the valence shell is held to the nucleus, the harder it is to remove an electron.
Harder to remove = more ionization energy

28. Atomic Radius Increases Atomic Radius Increases