Group 1 (alkali metals) – lithium, sodium and potassium
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What are the properties of group 1 metals?
• soft metals • Have relatively low densities and low melting points • Very reactive
Describe how lithium reacts with water
Fizzes steadily
Describe how sodium reacts with water
Melts into a ball then fizzes quickly
Describe how potassium reacts with water
Gives off sparks and hydrogen burns with a lilac flame
Explain the trend in reactivity in Group 1
• As you go down group 1, the number of shells of electrons increases by 1 • The outermost electron gets farther away from the nucleus, so there are weaker forces of attraction between the outermost electron and the nucleus • Therefore, less energy is required to overcome the forces of attraction as it gets weaker, so the outer electron is lost more easily
a reaction occurs when a small piece of potassium is added to water in a trough. State two observations that could be made during the reaction.
• Fizzing • Hydrogen burns with a lilac flame
Explain why potassium is more reactive than lithium
• loses its outer electron more easily considering it is further from the nucleus and less strongly attracted to it.
Give the formula of the ion that caused the flame to be lilac
K +
Describe how you could show that an alkaline solution is formed when caesium reacts with water
• Add the red litmus paper • It will turn blue
Suggest why the height of the precipitate eventually stops increasing as more lead(II) nitrate solution is added,
The sodium chloride has been used up
Why would you expect solid lithium nitride not to conduct electricity
• Ions cannot move
Identify the physical property that shows a clear trend
Melting point
State two similarities and two differences between the reactions of lithium and potassium with water
Similarities: - they both fizz - Forms a solution Differences: - Hydrogen burns with a lilac flame - Moves around faster/vigourously