Reactions of alkali metals with halogens When the alkali metals react with the different halogens (Group 7 of the periodic table), the group of compounds formed are known as the alkali metals halides.

This video excerpt from NOVA's "Hunting the Elements" explains why some elements are more reactive than others.

Chemical properties of Metals Metals are very reactive and tend to losses electrons easily and form positively charged ions; therefore metals are called electropositive elements.

A high-speed camera snaps sharp details of how alkali metals explode in water — a classic, but until now, not fully explained chemical reaction.

Reactions of alkali metals with oxygen When the alkali metals are cut, they initially appear shiny grey but quickly become dull and white as they react with oxygen in the air.