The Periodic Table: Group Properties

Group Properties: Alkali Metals (Group 1)

The Alkali Metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).
They are characterised by having one electron in their outermost shell, making them very reactive.
As you go down the group, the reactivity increases. This is due to the outermost electron being further from the nucleus, making it easier to lose and thereby increasing reactivity.
Alkali Metals react vigorously with water to produce alkaline solutions and hydrogen gas.
They all have low densities and melting points compared to most other metals.

The Alkaline Earth Metals include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra).
They have two electrons in their outermost shell, which contributes to their chemical properties.
Reactivity increases down the group, similar to Group 1, due to the outer electrons being further away from the nucleus.
Alkaline Earth Metals also react with water to produce alkaline solutions, but do so less vigorously than Alkali Metals.

The Halogens include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
They all have seven electrons in their outermost shell, making them highly reactive, as they need just one more electron to achieve a full outer shell.
Unlike Groups 1 and 2, reactivity decreases down the group. This is because the atoms are larger and the outermost electrons are further from the nucleus, making it harder to gain an additional electron.
Halogens exist as diatomic molecules (two atoms) in their elemental state.
They have varying physical states at room temperature: fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid.

The Noble Gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn).
They all have a full outer shell of electrons, making them extremely stable and unreactive.
The boiling and melting points of the Noble Gases increase down the group due to an increase in van der Waals forces as the size of the atoms increase.
They are all colourless gases at room temperature and are commonly used in lighting and lasers due to their ability to emit light when electricity is passed through them.