1.1.16

Halogens

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Displacement Reactions - Examples

Less reactive halogens can be displaced by more reactive halogens from compounds. In other words, it takes the place of the less reactive element. Below are some examples of different types of displacement:

Substitution

  • The substitute takes the place on the pitch of the other footballer, replacing him in the team.

Cannonball

  • By bombing into the water, this person displaces (replaces) some of the water in the swimming pool.

Halogens (Group 7) - Properties

Elements in group 7 in the periodic table are called halogens. Halogens have 7 electrons in their outer shell. They are very reactive because they easily accept an electron into this outer shell. They have similar properties and react in similar ways.

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7 outer electrons

  • Halogens are in group 7 and so have 7 electrons in their outer shell.
  • When they react, they gain 1 electron to get a full outer shell.
  • By gaining 1 electron, they form a negative ion.
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Diatomic molecules

  • In their elemental form, halogens share electrons to make diatomic molecules (molecules made of pairs of atoms).
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Salts

  • When a metal atom transfers its outer electron to a non-metal atom (like a group 7 atom), salts are formed.
  • The result is a compound where all the ions have a full outer shell.
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Reactivity

  • As you move down the group, the halogens decrease in reactivity. This is because:
    • The atoms gain more electron shells.
      • So, the distance between the outer electron shell and the nucleus increases.
        • So, the attraction between the nucleus and the electron (to be gained from another element) decreases.

Jump to other topics

1Atomic Structure

2Chemical Bonding

3Quantitative Chemistry

4Chemical Changes

5Energy Changes

6The Rate & Extent of Chemical Change

7Organic Chemistry

8Chemical Analysis

9Chemistry of the Atmosphere

10Using Resources

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