Halogens (Group 7)

• What group are the halogens in?

  7
• Fluorine, F² is what colour and state at room temperature?

  pale yellow gas
• Chlorine, Cl² is what colour and state at room temperature?

  yellow/green gas
• Bromine, Br² is what colour and state at room temperature?

  red/brown liquid
• Iodine, I² is what colour and state at room temperature? And what does it give off when it is heated?

  dark grey solid, when heated gives off a purple vapour
• As you go down group 7, the melting point, boiling point increases. The intermolecular forces between their molecules get stronger, which means more heat energy is needed to overcome them. However, the reactivity decreases
• When halogens react with metals, what do they form?

  Metal Halides
• Why do halogens form metal halides?

  the halogen atoms gain electrons and are reduced.
• Complete the half equation.

  Cl² + 2e- -> 2Cl²-
• Halides are compounds of


  metals/hydrogen with halogens
• Going down group 7, why does the reactivity decrease?

  As more full electronic shells are added, the forces of attraction gets weaker. Electrons are gained less easily, and the elements become less reactive
• As the number of shells increases:

  electrons become further away from the nucleus. This extra shell that is added creates a 'shield' between the nucleus and the outer shell, so reactivity decreases
• What can a more reactive halogen do to a less reactive halogen from its compounds?

  displace it
• Define OIL RIG

  Oxidation Is Loss, Reduction Is Gain
• Halogen displacement reactions are:

  Redox reactions
• You can demonstrate displacement reactions by:

  adding a halogen solution to a metal hydroxide solution, then seing if it darkens.
• Chlorine in 'chlorine water' displaces bromine from aqueous sodium bromide solution because it is more reactive
• Complete the ionic equation

  Cl² + 2NaBr -> 2NaCl + Br²

  Cl² + 2Br‐ -> 2Cl‐ + Br²
• Oxidation and Reduction happens at

  the same time