CONCEPT MAP

The unit's concept map is rooted at "Alkali Metals (Li, Na, K, Rb, Cs)" and branches into three linked strands.

The Physical Properties strand lists: common oxidation state +1; atomic and ionic radii increasing down the group; and ionisation enthalpy, electron affinity and electronegativity all decreasing down the group.

The Chemical Properties strand branches out by reagent, each arrow labelled with what is added: +O2 leads to Li2O (lithium's own simple oxide) on one branch and to Na2O2 / MO2 (M = K, Rb, Cs -- peroxide / superoxide) on another; +H2 leads to the ionic hydrides MH (M = Li, Na, K, Rb, Cs); +X2 leads to the ionic halides MX (M = Li, Na, K, Rb, Cs; X = F, Cl, Br, I); +H2O leads to the hydroxides MOH; and +C leads to Li2C2 directly from lithium, while for the other metals an alkyne (HC≡CH) is first converted to its acetylide, MC≡CM (M = Na, K, Rb, Cs). …