Periodicity

1. Transition metals
- Form colored compounds.
- Exhibit variable oxidation state (e.g. iron has an oxidation state of +2 and +3).
- Make good catalyst
- High melting point, boiling point, and density

2. Noble gas (Group VIII or 0)
- non- reactive
- (generally) do not form compounds, as they have stable electronic configuration

3. Group I
- reactivity increases down the group.
- react vigorously with cold water to give hydroxides and hydrogen.
- have a lower density, and melting point than other metals.
- form carbonates that are stable to heat.

4. Group VII
- reactivity decreases down the group.
- color intensity increases down the group.
- melting point, boiling point and density increases down the group.
colours of molecules, group VII molecules, color intensity increases down the Group VII
Colours of Group VII elements









-exist as diatomic molecules  e.g. Cl2, Br2, I2, At2, F2

-undergo displacement reaction, where a more reactive halogen will displace a less reactive halogen.

Ex. 1 Br2 + MgCl2 --? No reaction
Thought process:
Br vs Cl.
Cl is more reactive, since it is higher in the periodic table.
More reactive halogen must be by itself, less reactive halogen must be in ionic form (or compound).
-But Cl exists as compound here
-Condition NOT satisfied
-No reaction!

Ex. 2 Br2 + 2NaI --> I2 + 2NaBr
Thought process:
I vs Br.
Br is more reactive, since it is higher in the periodic table.
More reactive halogen must be by itself, less reactive halogen must be in ionic form (or compound).
-Br is by itself.
-Condition satisfied
-Got reaction!

Related Posts
- Metals
- Rusting

Questions
- Quizzes and Tests on Periodicity

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