2.These elements are known as alkali metals.
Physical Properties
1.Alkali metals are grey solids with shiny silvery surfaces when freshly cut.
2.These surfaces turn dull when exposed to air.
3.This is because alkali metals are very reactive.They react rapidly with oxygen and water vapour in the air when exposed.
4.Alkali metals are soft solids and can be easily cut.
5.Alkali metals have low densities as compared to heavy metals.
6.Alkali metals are good conductors of heat and electricity.
7.Alkali metals have low melting and boiling point as compared to heavy metals.
Chemical Properties
1.Table below shows the electron arrangements of alkali metals.
Element
|
Electron
arrangement
|
Lithium
|
2.1
|
Sodium
|
2.8.1
|
Potassium
|
2.8.8.1
|
Rubidium
|
2.8.18.8.1
|
Caesium
|
2.8.18.18.8.1
|
Francium
|
2.8.18.32.18.8.1
|
3.This is because all the atoms of alkali metal have one valence electron.
4.Alkali metal are very reactive.
5.The reactivity of alkali metals increases when going down Group 1.
6.This is because the when going down the Group 1, the atomic size of alkali metals increase.
7.The single valence electron becomes further away from the nucleus and is screened by more inner shells containing electron.
8.This cause the single valence electron to be more weakly pulled by the nucleus.
9.Hence, the single valence electron can be released more easily when going down Group 1.
