Inorganic Chemistry/Group 1 metals

Group 1A - ALKALI METALS

These consist of:
Li Lithium [He] 2s¹
Na Sodium [Ne] 3s¹
K Potassium [Ar] 4s¹
Rb Rubidium [Kr] 5s¹
Cs Cesium [Xe] 6s¹
Fr Francium [Ra] 7s¹

Fr is radioactive (half-life 21 min.) hence very little is known about it

Physical Properties

1) Silvery white soft solid, can be cut with a knife except Li
2) Highly malleable and ductile
3) Silver lustre is due to the presence of highly mobile electrons of the metallic lattice
4) Large size in their respective periods; size increases down the group
5) IE (ionisation enthalpy) decreases down the group
6) They show +1 oxidation state
7) Reducing character increases from Na to Cs, however Li is strongest reducing of them all
8) They have very low melting points due to weak metallic bonds
9) Density increases from Li to Cs (except K being lighter than Na)
10) Ionic character increases from Li to Cs
11) They are good conductors of heat and electricity

Chemical Properties

1. Reaction with oxygen:
Alkali metals tarnish in air due to formation of oxide or hydroxide on their surface.
When heated in excess of air Li forms normal oxide, Na forms peroxide and others form superoxide
K can form all the three types of oxides (also it forms KO₃ and K₂O₃)
4Li + O₂ → 2Li₂O
2Na + O₂ → Na₂O₂
K + O₂ → KO₂

2. Reaction with water:
2Na + 2H₂O → 2NaOH + H₂

3. Reaction with liquid ammonia:
2Na + 2NH₃ → 2NaNH₂ + H₂

Group 1B - TRANSITION METALS

These consist of:
Cu Copper
Ag Silver
AU Gold