Group 1 and Group 7

Group 1 - Alkali Metals:

Group 1 metals, known as alkali metals, include Lithium, Sodium, Potassium, Rubidium, Cesium, and Francium.
These metals tend to be very reactive as they readily donate their single electron located in their outer shell.
Alkali metals have low melting and boiling points which decrease down the group.
They have low densities, and these densities also tend to decrease down the group.
Reactions of these metals with water produce metal hydroxides and hydrogen gas.
Alkali metals react with non-metals to form ionic compounds, in which they carry a positive charge.
As you move down Group 1, reaction rates increase as the metals lose their outer electron more easily.

Group 7 - Halogens:

Group 7 elements, known as halogens, include Fluorine, Chlorine, Bromine, Iodine, and Astatine.
Halogens are non-metals with seven electrons in their outer shell, meaning they often gain an electron in reactions and become negatively charged ions.
They have higher melting and boiling points than alkali metals, which increase down the group.
Reactive characteristics of halogens decrease when moving down Group 7, as gaining an electron becomes harder.
Halogens become darker in colour as you move down the group.
They form salts when reacting with metals and can displace less reactive halogens from their salts.
Chlorine, for example, is a pale green gas, bromine is a red-brown liquid, and iodine is a dark grey solid or purple gas.

Remember to understand the trends in properties and reactivity. Practice using these trends to predict the properties of unfamiliar elements within these groups.