Introduction

Groups 1 and 2 sit on the far left of the periodic table; in both, the last electron added enters an 's' subshell, which is why both belong to the s-block. Group 1 consists of hydrogen, lithium, sodium, potassium, rubidium, caesium and francium; all of these except hydrogen (already covered separately in section 8.1) are collectively called the alkali metals. Of these, sodium and potassium are respectively the sixth and seventh most abundant elements in the Earth's crust, while francium barely occurs in nature at all because it is radioactive with a very short half-life. Group 2 consists of beryllium, magnesium, calcium, strontium, barium and radium, collectively called the alkaline earth metals because they occur naturally as minerals in rocks ('earths'). Magnesium and calcium are abundant in th …