Specification Point 2.5:
Know the colours, physical states (at room temperature) and trends in physical properties of these elements

The Physical Properties of Halogens

Halogens: Group 7 non-metals that are poisonous and includes: Fluorine, Chlorine, Bromine, Iodine and Astatine.

Halogens are diatomic, meaning they form molecules of two atoms.

Colours and States at Room Temperature:

Table Halogen Properties, Edexcel IGCSE Chemistry

Trends in Physical Properties:

  1. Melting Point

The Melting and Boiling Points of Halogens increases as you go down the group

Melting:boiling points of halogens, CIE IGCSE Chemistry

Melting and boiling points of Halogens

  1. State at Room Temperature
  • At room temperature (20 °C), the physical states of the Halogens become more hard and set.
  • Chlorine is a gas, bromine is a liquid and iodine is a solid.
States of halogens, CIE IGCSE Chemistry

States of Halogens

  1. Colour
  • The Halogens become darker as you go down the group.
  • Chlorine is pale green, bromine is red-brown and iodine is black.
Colours of halogens, CIE IGCSE Chemistry

Colours of Halogens

Specification Point 2.6:
Use knowledge of trends in Group 7 to predict the properties of other Halogens

Predicting the Properties of Halogens

Properties of other Halogens (Fluorine and Astatine):

Melting and Boiling Point

  • The melting and boiling point of Halogens increases as you go down the group
  • Fluorine is on the top of Group 7 so will have the lowest melting and boiling point
  • Astatine is on the bottom of Group 7 so will have the highest melting and boiling point

States

  • The states of Halogens become more hard and set as you go down the group
  • Fluorine is on the top of Group 7 so will be a Gas
  • Astatine is on the bottom of Group 7 so will be a Solid

Colour

  • The colour of Halogens become darker as you go down the group
  • Fluorine is on the top of Group 7 so the colour will be lighter: Yellow
  • Astatine is on the bottom of Group 7 so the colour will be darker: Black

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.