The Alkali Metals, the Transition Elements and the Halogens

GROUP 1 - THE ALKALI METALS

The alkali metals react readily with air and water.  They are soft solids at room temperature with low melting and boiling points that decrease going down the group.  They have low densities, so the first three (lithium, sodium and potassium) float on water.  They react with water to produce hydrogen gas and a metal hydroxide that is an alkali.

Lithium + water -------> lithium hydroxide + hydrogen

They all have one electron in the highest energy level.  They lose this electron in ionic bonding and the ions have a single positive charge, eg Na+.  They react with the halogens to form salts that are white or colourless crystals.

Sodium + chlorine -------> sodium chloride

Compounds of alkali metals dissolve in water, forming solutions that are usually colourless. The reactivity increases going down…