Group 1

Key Stage 4

Meaning

Group 1 elements, also known as Alkali Metals on the Periodic Table are the elements which have only one electron in their outer shell.


Group 1 elements are shown in light purple at the far left of the Periodic Table. NB: Hydrogen is often shown in Group 1 due to having a single electron in the outer shell however it is not considered an Alkali Metal because it has very few properties in common with Alkali Metals.

About the Alkali Metals

Though Hydrogen has one electron in the outer shell it does not behave the same as other elements in group 1 so it is not considered to be an Alkali Metal.

The Alkali Metals have similar chemical properties because they all have one electron on their outer shell.

Alkali Metals all produce ions with a +1 relative charge because they lose an electron in chemical reactions.

The Alkali Metals in order from least reactive to most reactive are:

Lithium (Li)
Sodium (Na)
Potassium (K)
Rubidium (Rb)
Caesium (Cs)
Francium (Fr)

Chemical Properties

Alkali Metals are all highly reactive and will oxidise quickly in the presence of Oxygen.

Alkali Metals all react strongly with water to produce metal hydroxides and Hydrogen gas.

Alkali Metals all produce strong alkalis.

		In a chemical reaction the electron in the outer shell is lost. The reactivity increases as you go down the group because: The outer electron is further away from the nucleus with each additional electron shell making the force of attraction weaker. This makes it easier for an atom to lose it's outer electron. Even though the charge of the nucleus increases the outer electron is shielded from most of the positive charge of the nucleus by electrons in the inner shells.

Physical Properties

Alkali Metals have a low density compared to other metals.

Alkali Metals are all solid at room temperature but have a low melting point compared to other metals.

Alkali Metals are soft and can be easily cut.

Alkali Metals all appear shiny (before they oxidise).

References