Group 7 Flashcards
What group are the halogens in? Why?
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 colour and state of bromine at room
temperature?
Red-brown liquid
What is the colour and state of iodine at room
temperature?
Black solid
Why are the halogens at different states at room
temperature? What is the trend down the group?
At room temperature, chlorine is gaseous,
bromine is liquid and iodine is solid because they
have different melting and boiling points. As you
go down the group, melting and boiling point
increases.
What state would you expect the halogens fluorine
and astatine to be at room temperature?
Fluorine is above chlorine so should have a boiling point
lower than chlorine. This means it would be a gas at room
temperature.
Astatine is below iodine in group 7 so should have a higher
melting point than iodine. Therefore you can predict that it
would be a solid at room temperature.
Why does melting and boiling point increase down Group 7?
The molecules get bigger down the group so there are more intermolecular forces to overcome during melting / boiling so more energy is required.
What is the chemical test for chlorine?
Damp litmus paper placed into a test
tube of gas. If chlorine is present, the
litmus paper 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
E.g: Cl2 , Br2…
What charge does a halide ion carry? Why?
- 1
e. g. Cl-, Br-…
They gain one electron to have a stable
electron configuration.
What is produced when a halogen reacts with a
metal?
Metal halide salt
Write a balanced symbol equation for the reaction
between bromine and sodium
Br2 + 2Na → 2NaBr (check google if unsure)
Write a balanced symbol equation for the reaction
between chlorine and calcium
Cl2 + Ca → CaCl2 (check google if unsure)
Predict the product of the reaction between
magnesium and fluorine
Magnesium fluoride (MgF2)
Write a word equation for the reaction between
iodine and potassium
Iodine + potassium → Potassium iodide.
Remember: the ion of a halogen ends
with -ide.
Describe the trend in reactivity of the halogens. How
does this affect the rate of reaction?
Reactivity decreases down group 7.
Rate of reaction decreases down group 7
What is formed when hydrogen reacts with a
halogen?
Hydrogen halides
e.g. HCl, HBr…
Chlorine reacts with hydrogen in the presence of
sunlight but bromine requires a flame. Why?
Reactivity decreases down the group so
bromine requires more energy for the
reaction to occur
What is formed when a hydrogen halide dissolves in
water?
An acidic solution. Hydrogen ions
dissociate, making the solution acidic.
Write a balanced symbol equation for the reaction
between hydrogen and chlorine
H2 + Cl2 → 2HCl (check if unsure)
Predict the product of the reaction between
hydrogen and fluorine
Hydrogen fluoride (HF)
When does a halogen displacement reaction occur?
When a more reactive halogen displaces
a less reactive halogen from an aqueous
solution of its halide.
Why will halide ions A only be displaced by halogen
B if B is above A in group 7?
The most reactive halogen (B) will displace the
less reactive halogen (A) to become part of the
ionic compound. Reactivity increases as you go
up the group so B must be higher in group 7 to
be more reactive than A
Which halogens can chlorine displace from an
aqueous ionic solution?
Chlorine can displace any halogens
below it in group 7. It will displace iodine
and bromine.
