What are group 1 called?
Alkali metals (they form alkaline solutions when they react with water)
What are group 2 called?
Alkaline earth metals (also form alkaline solutions when they react with water)
Properties of Group 1 metals
Soft (cut with knife)
Low densities
Low melting points
Very reactive (only one valance electron)
Reaction of Group 1 metal with water
Group 1 metal + water ⟶ metal hydroxide + hydrogen
What are the observations when lithium reacts with water
Fizzing and lithium moves slowly on the surface of the water
What are the observations when sodium reacts with water
More vigorous fizzing sodium moves rapidly on the surface, melts into ball and dissolves quickly
What are the observations when potassium reacts with water
Very vigorous reaction potassium moves very rapidly, melts into ball and burns with a lilac flame
What is the trend in observations when Group 1 metals react with water
Reactions become more vigorous down the group with faster movement more fizzing and potassium producing a lilac flame
Why does reactivity increase down Group 1
Valence electron is further from the nucleus and forces acting on it are weaker so it is lost more easily making the reaction faster
What happens when alkali metals react with oxygen
They form metal oxides which appear as a dull coating on the surface causing the metal to tarnish
What is the observation when lithium reacts with oxygen (heated)
Burns with crimson flame
White solid is formed
What is the observation when sodium reacts with oxygen (heated)
Bright yellow flame
White solid
Melts
What is the observation when potassium reacts with oxygen (heated)
Lilac flame
White solid
Vigorous
Melts
What is the trend in tarnishing down Group 1
Metals tarnish more rapidly as you go down the group because they become more reactive
Why are group 1 metals are stored in oil?
To prevent tarnishing
Physical trends in group 1
Softer down the group
First 3 less dense than water
Melting Points decrease going down the group
Why does melting point decrease down Group 1 metals?
The positive ions get larger so the delocalised electrons are further away and the electrostatic attraction is weaker so metallic bonding is weaker and less energy is needed to break the lattice
What do group 1 metals look like?
Shiny silver when cut
tarnish fast
dull grey
soft can cut with knife
Why does Group 1 reactivity increase down the group
Valence electron further from nucleus more shells weaker attraction less energy needed electron lost easier so reactivity increases
Are the group 1 metals conductive (heat + electricity)?
Yes
What is the observation when Lithium reacts with chloride (heated)
Bright red flame
White smoke
White solid product
What is the observation when Sodium reacts with chloride (heated)
Melts
Bright yellow flame
White smoke
White product
What is the observation when Potassium reacts with chloride (heated)
Melts
Lilac flame
White smoke
White product
Very vigorous
