Ions

Valence Shell Valence Shell: The most outer energy level. 1s22s22p63s23p3 1s 2s 2p 3s 3p

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

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

Valence Electrons: Label on your PTE 1 8 2 3 4 5 6 7

Group 1 s p s p New valence shell

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

- - + -

- - + - + + + + - -

- - + - + + - + + - - -

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

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

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

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… …

Number of Valence Electrons Li Be B F O N Cl P K Ca Al Se Br Kr

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

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

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?

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

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

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

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

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

Name the ions formed by these elements Li Be B F O N Cl P K Ca Al Se Br Kr

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.

Ionization Energy Increases Ionization Energy Increases

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

Atomic Radius Increases Atomic Radius Increases