1. Ionic versus Atomic Radius

2. When an atom forms a positive ion (by losing electrons) its radius also changes. 3p e-e- e-e- e-e- e-e- e-e- 13p e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- LiLi 1+ AlAl 3+

3. Ionic versus Atomic Radius When an atom forms a negative ion (by gaining electrons) its radius also changes. 16p e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- 9p e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- 16p e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- FF 1- SS 2-

4. Cations (positive ions) become smaller than their neutral atoms. Anions (negative ions) become larger than their neutral atoms. Ex. (1) Ca 2+ is ____________________ in size than Ca. Ex. (2) Se is ____________________ in size than Se 2-. Ex. (3) In each of the following pairs, circle which species is the larger. (a) F or F 1- (b) Fe 2+ or Fe (c) Kr or Br Ionic versus Atomic Radius smaller

5. Ex. (4) Rank the following species from largest to smallest: Si, Si 4+, Se, Se 2-, Kr (CONSULT TABLE-S) –Si has a radius of 114 picometers –Se has a radius of 118 picometers –Kr has a radius of 116 picometers Se > Kr > Si Se 2- will be larger than Se and Si 4+ will be smaller than Si Se 2- > Se > Kr > Si > Si 4+ Ionic versus Atomic Radius

6. Ex. (5) In the reaction, Fe  Fe 2+ + 2 e 1-, as the atom forms the ion its size _____________________. Ex. (6) In the reaction, Se + 2 e 1- → Se 2-, as the atom forms the ion its size _____________________. Ex. (7) From what group of elements on the Periodic Table are the atoms the least likely to ionize? ___________________ Ex. (8) Based on the diagrams below, is element X a metal or a nonmetal? Atom of Element XIon of Element X Element X is a ________________. Ionic versus Atomic Radius increases decreases nonmetal Noble gases (group 18)