Section 2 - Pgs 30-33 Flashcards
Do Group 7 elements take part in displacement reactions?
Yes
What is a displacement reaction?
Where a more reactive element ‘pushes out’ (displaces) a less reactive element from a compound.
What happens when chlorine water is added to potassium iodide and why?
Potassium chloride and iodine are formed. This is because the chlorine is more reactive than the iodine, which causes it to displace the iodine. The iodine turns the solution brown.
Describe an experiment to demonstrate that a more reactive halogen will displace a less reactive one from a solution of its salt.
1) Prepare 3 salt solutions: chlorine salt solution, bromine salt solution, iodine salt solution (e.g. potassium chloride solution)
2) Add chlorine water to each of these and watch for colour change.
3) A colour change shows that chlorine is more reactive than the halogen in that salt.
4) Repeat, adding bromine water and then iodine water instead of chlorine water.
What happens to the colour of a solution when bromine is displaced?
Turns orange
What happens to the colour of a solution when iodine is displaced?
Turns brown
Complete the equation:
Cl2 + 2KI ->
Cl2 + 2KI -> I2 + 2KCl
Chlorine + Potassium iodide -> Iodine + Potassium chloride
Usually, what type of reactions are displacement reactions?
Redox reactions
What is a redox reaction?
When reduction and oxidation happen at the same time.
What is an oxidising agent?
It accepts electrons and gets reduced.
What is a reduction agent?
It donates electrons and gets oxidised.
In halogen displacement reactions, what gets reduced and what gets oxidised?
Reduced: Halogen - The halogen gains electrons to make it negatively charged so it can form an ionic bond.
Oxidised: Halogen in Salt - The halogen in the salt loses electrons so that it is no longer negatively charged and is once again an atom.
What are the horizontal rows of the periodic table called?
Periods
What are the vertical columns of the periodic table called?
Groups
Describe the relationship between the elements in a group.
- Generally have similar properties -> Due to same no. of outer electrons
- Properties gradually change as you go down the group (e.g. reactivity)
Where are the elements on the left of the periodic table?
Metals
What are the elements on the right of the periodic table?
Non-metals