group 7

• what group are the halogens in

  group 7 because they have 7 outer shell electrons
• what is the colour and state of chlorine at room temperature

  pale green gas
• what is the state and colour of bromine at room temperature

  red-brown liquid
• what is the colour and state of iodine at room temperature

  black solid
• why are halogens at different states at room temperature , what is the trend down the group

  as you go down the group , the melting and boiling point increases , this is why iodine is a solid and chlorine is a gas
• what state would you expect fluorine and astatine to be at room temperature

  fluorine:gas

  astatine:solid
• what is the chemical test for chlorine 


  damp litmus is placed into a test tube of gas , if chlorine is present , the litmus papr will turn red then white due to the bleaching effect of chlorine
• halogens are diatomic , what does this mean 


  they form molecules consisting of 2 atoms
• why are group 1 metals very reactive 


  they readily lose their single outer electron to form a 1+ ion with a stable electronic structure , this means that it is very reactive
• do alkali metals form ionic compounds

  yes
• what charge does a halide ion carry and why

  1. because they have to gain one electrons to have a full outer shell
• what is produced when a halogn reacts with a metal

  metal halide salt
• reaction between potassium and iodine

  potassium iodide
• what happens to the reactivity as you go down group 7

  reactivity decreases
• what is formed when hydrogen reacts with a halogen

  hydrogen halides
• chlorine reacts with hydrogen in sunlight but bromine needs a flame , why is this

  reactivity decreases as you go down the group meaning that bromine needs more energy than chlorine for the reaction occur
• what is formed when a hydrogen halide dissolves in water

  hydrogen hallides are soluble , it forms an acidic solution , hydrogen ions dissacosiate , making the solution acidic
• when does a halogen displacement reaction occur

  when a more reactive halogen displaces a less reactive one from an aqeuous solution of its halide
• what halogens can chlorine displace

  any halogens which are below it in the group e.g bromine
• write the word equation for the reaction for the reacion between bromine and calcium chloride

  no reaction will occur because bromine is less reactive that chlorine as it is lower down in the group
• which halogens would astatine be able to displace

  none as it is at the bottom of group 7 meaning it is the least reactive therefore it cant displace any other halogens
• why does reactivity decrease as you go down group 7

  as you go down group 7 , the outer shell is further from the nucleus and electron shielding increases , attraction between the nucleus and the outer electrons decreases aswell therefore it is harder for the atom to gain an electron meaning reactivity decreases
• what colour is chlorine water

  colourless
• what colour is bromine water

  orange
• what colour is iodine solution

  brown
• what would you observe when chlorine water is added to potassium bromide

  the solution would turn colourless water into orange water as chlorine will displace bromine
• what is a redox reaction

  a reaction where oxidation and reduction takes place at the same time
• are halogen displacement reactions redox reactions


  yes because the halide ion is oxidised (loses electron) to form a halogen atom and the halogen is reduced ( gains electrons ) to become a metal halide ion
• bromine reacts with potassium iodide , what is reduced and what is oxidised


  bromine is reduced to bromide ion

  iodide ions are oxidised to iodine atoms