The Halogens Flashcards
What group elements are referred to as halogens?
7
List 2 properties of halogens
Low melting and boiling points
Exist as diatomic molecules
What is the trend in boiling point down group 7? Why?
Increases down the group because: - size of atom increases as more occupied electron shells - stronger London forces of attraction between molecules Takes more energy to break
What is the trend in reactivity down group 7? Why?
Decreases
Atomic radius increases
Electronic shielding increase Ability to gain and electron to form negative ions decreases
What is the trend in oxidising ability down the group?
Why?
Decreases down group Cl strongest.
This is because Cl has the fewest occupied electrons shells, greatest force of attraction between outer electrons and nucleus and thus is the easiest to gain electrons and be reduced/ best oxidising agent
What is the trend in reducing ability down the halides? Why?
Increases down group (I- strongest)
This is because I- has the most occupied electron shell so the outer electrons are further form the nucleus.
Weakest force of attraction between outer electrons and positive charge of nucleus and thus is the easiest to be oxidised and lose electrons —> best reducing agent
When a more reactive halogen displaces a less reactive halide, what is the reaction called?
Displacement
What is the colour of chlorine in water?
Pale green
What is the colour of bromine water?
Orange
What is the colour of iodine in water ?
Brown
What is the colour of chlorine in cyclohexane ?
Pale green
What is the colour of bromine in cyclohexane?
Orange
What is the colour of iodine in cyclohexane?
Violet
Out of the 3 Cl- Br- I- halides which can be oxidised by chlorine?
Br- and I- ions
White an equation for chlorine oxidising bromine ions
Cl2 + 2Br- —> 2Cl- + Br2
