Group I properties
Group I — the alkali metals
- Lithium, sodium, potassium are soft metals (you can cut them with a knife).
- Each atom has one electron in its outer shell.
Practice
Each Group I atom has how many electrons in its outer shell?
Group I (the alkali metals) have one outer-shell electron, which they lose to form +1 ions.
Trends down the group
| Property | Going down |
|---|---|
| melting point | decreases |
| density | increases |
| reactivity | increases |
- So rubidium (below potassium) is even more reactive with a lower melting point.
Practice
Going down Group I, the reactivity:
Reactivity increases down Group I (potassium is more reactive than sodium).
Practice
Rubidium (below potassium) would be more reactive and have a lower melting point than potassium.
Following the trends: more reactive and lower melting point as you go down the group.
You've got it
Key idea
- Group I = alkali metals (Li, Na, K), soft, one outer electron
- going down: melting point down, density up, reactivity up
- predict lower elements: more reactive, lower melting point