C8.2 Group I properties

Describe characteristics of the alkali metals

• Group 1 elements

• 1 electron in outer shell (1+ charge)

• Relatively soft and can be cut with knife

• Must be stored in oil

• Shiny, silvery and good conductors of heat and electricity

• Make alkaline solutions (blue - purple)

Describe group I trends relating to decreasing melting point

• The melting point of the alkali metals decreases as you go down the group

  • This is because the strength of the metallic bonds decreases, so less energy is required to break these bonds and turn the solid into a liquid

Describing group I trends relating to increasing density

• The density of the alkali metals increases as you go down the group

• All group I elements have low density and float on water

Describe group I trends relating to increasing reactivity with water (explain)

• The reactivity of the alkali metals increases as you go down the group

  • Atomic radius increases (or there are more electron shells)

  • There is weaker attraction between the nucleus and the outer electron

  • The outer electron is lost more easily

Describe the reaction of potassium with water (and chemical equation)

• Floats

• Fizzes

• Melts into a ball and catches fire with a lilac flame

Describe the reaction of sodium with water (and chemical equation)

• Floats

• Fizzes

• Melts into a ball as it reacts

Describe the reaction of lithium with water (and chemical equation)

• Floats

• Fizzes

• Keeps its shape as it reacts