Group 7 - The halogens Flashcards
What is the colour of flourine at gaseous state?
Pale yellow
What is the colour of chlorine at gaseous state?
green
What is the colour of bromine at liquid state?
Red brown
What is the colour of iodine at solid state?
Grey
What is the trend of the electronegativity going down group 7 and why ?
Electronegativity decreases due to the increases in atomic radius therefore proton being further away and less capable of attracting pair of electrons
What is the trend of the boiling point as you go down group 7 and why ?
Boiling point increases due to the increase of van der waal forces as the size and relative mass increases
What happens when a halogen reacts with a halide ion in a solution?
Halogen will displace a halide ion from its solution if the ion is less reactive
What does chlorine and sodium hydroxide react to make?
sodium chlorate (I) solution which is household bleach (kills bacteria)
What occurs when chlorine mixes with water?
chlorine undergoes disproportionation therefore you end up with a mixture of chloride ions and chlorate (I) ions
What is disproportionation?
It is when an element has different charges throughout a reaction due to being oxidised and reduced
What occurs when chlorine mixes with water in sunlight?
In sunlight, chlorine decomposes water to form chloride ions and oxygen
What is a use Chlorine?
Water treatment
Pros of using chlorine for water treatment?
- It kills disease causing microorganisms
- Some chlorine persists in water and therefore prevents reinfection
- Prevents growth of algae elimination bad taste and smells
Cons of using chlorine for water treatment?
- It irritates the respiratory system if breathed in
- Liquid chlorine causes severe burns
- chlorine reacts with a variety of hydrocarbons in water and when it does it produces chlorinated hydrocarbons which are carcinogenic (cancer causing).
