C7 - Periodicity (Gen. Chem 1)

atomic radius

½ distance between two colliding atoms of the same type

• increases down and to the left of the table

ionization energy

energy required to remove a valence electron from its atom

• increases up and to the right of the table

electron affinity

ability for an atom to gain an electron (the energy ∆)

• noble gases: 0

• halogens: very negative

• column 5A: usually 0 or +

• little change going up & down

alkali metals

• silvery

• lustrous

• very reactive

• colorless ions

• high conductivity

alkaline earth metals

• relatively reactive

• solids

• denser than alkali metals