2 Group 1 (The Alkali metals) Flashcards
What are the elements in group 1 of the periodic table called?
The Alkali metals.
What happens to their melting and boiling points as you go down the group?
They get lower.
What happens to their densities as you go down the group?
They increase even though the first three stay the same.
What happens to their softness as you move down the group?
They become softer as you move down the group; and are shiny and silver when freshly cut but quickly tarnish when exposed to air.
What happens to their reactivities as you go down the group?
They increase.
What do we store the alkali metals in?
Oil, to ensure that no oxygen can react with them.
What are the similar chemical properties of alkali metals?
- They all react with water in the same way to form a hydroxide and a hydrogen.
- They react with oxygen to form an oxide with the formula M2O or K2O.
-They form ionic compounds with positive ions.
How do they react with water? (formula)
Alkali metal + water-> Alkali metal hydroxide + hydrogen
What are some observations that you can make while watching sodium react with water?
- Sodium floats because it is less dense than water.
- It melts into a ball because the melting point is low and a lot of heat is produced in the reaction.
- There is fizzing because hydrogen gas is produced.
What are some observations that you can make while watching lithium react with water?
- Very similar to the reaction involving sodium, but it is slower.
- Lithiums melting point is higher and not as much heat is produced as quickly so the lithium doesn’t melt.
What are some observations that you can make while watching potassium react with water?
- Its reaction is faster than sodiums.
- Enough heat is produced to ignite the potassium which burns with a lilac flame.
- The reaction ends with potassium spitting around and exploding.
What are some observations that you can make while watching rubidium and caesium react with water?
- They react very violently.
- The reaction could potentially be explosive.
The bigger the atom the more …
Reactive it is, this is because the outer shell electron is further away so it is more likely to be lost as the forces between the negative electron and the positive nucleus isn’t as strong.
How can we see the increase in reactivity with alkali metals?
We can see that as we go down the group they react quicker and quicker with the air and they therefore tarnish much faster.
What colour is lithiums flame and what does it form?
Red flame and forms lithium oxide.
