Group 1

Group 1 Elements

• Known as the alkali metals, Group 1 elements include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).
• Alkali metals are located in the first column of the periodic table.
• They all have one electron in their outer shell, which makes them highly reactive and eager to donate that electron in chemical reactions.

Properties of Group 1 Elements

• Group 1 elements are soft and can be easily cut with a knife.
• They have low melting and boiling points, which decrease further down the group.
• They are good conductors of heat and electricity.

Reactivity of Group 1 Elements

• Group 1 elements are very reactive, and their reactivity increases down the group. This is due to the increasing distance of the outer electron from the nucleus.
• All these metals react vigorously with water to produce hydrogen gas and a metal hydroxide, leading to an alkaline solution.
• They also react with oxygen in the air, forming metal oxides. As a result, they are usually stored in oil to prevent reactions with air or moisture.

Group 1 Element Trends

• Atomic and ionic radii increase down the group due to the increasing number of electron shells.
• First ionisation energy, which is the energy required to remove the outermost electron, decreases down the group as the outermost electron is further from the nucleus and therefore less tightly held.
• Density usually increases down the group, with the exception of potassium, which is less dense than sodium.

Group 1 Element Compounds

• Compounds of alkali metals are often white solids that dissolve in water to form colourless solutions.
• Alkali metals form ionic compounds in which the metal ion carries a charge of +1.
• Common compounds include chlorides (e.g. sodium chloride, potassium chloride) and oxides (e.g. lithium oxide, sodium oxide).