Group 1 metals
Group 1 metals as known as Alkali Metals. The group contains the elements Hydrogen, Lithium, Sodium, Potassium, Rubidium, Cesium and Francium. They all contain one electron on their outermost shell and so share similar characteristics in terms of bonding. There are trends down the group that can be observed. As you go down the group the atomic radius of the elements increases due to more full electron shells. This decreases ionisation energy due to the greater atomic due to more full electron shells between the outer electron and the nucleus. This causes more electron shielding. There are more protons in the nucleus but there are also more electrons. This creates a lower electrostatic attraction to the nucleus due to the smaller effective nuclear charge. Melting point decreases due to a lower charge density and therefore weaker attraction between the positive ion and the electron. The outer electron can be lost more easily due to all of these factors and so reactivity increases down the group. They all, however, form a giant metallic structure.