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What are the group 7 elements



As you go down the group, what happens to the thermal stability, physical appearance, states, reactivity, volatility, mp/bp

Thermal stability decreases
Becomes darker in colour
Gases to liquids to solids
Reactivity decreases
Becomes less volatile
Mp/bp increases


What is a reducing agent

It's been oxidised and it reduces another ion


What are spectator ions?

Ions that don't change in a reaction


What is a displacement reaction?
What displaces each other in group 7?

When an atom pushes out another atom and takes its place
Chlorine displaces bromine and iodine
Bromine displaces iodine


What are the colours formed when halogens react with silver to form silver halides?
+ when ammonium solution is added?

Chlorine - White
Bromine - Cream
Iodine - Pale yellow

Chlorine - clear
Bromine - cloudy/bit clear
Iodine - insoluble


O I L R I G?

Oxidation Is Loss Reduction Is Gain


What are oxidation states useful for?

- Naming inorganic compounds
- Deciding what has been oxidised and what has been reduced
- identifying the oxidising agents and reducing agents
-balancing redox reactions


What is the oxidation states for :
- Element
- Simple ion
- Compound
- Complex compound

- 0
- the charge on the ion
- charges add to 0
- charges add to charge on the compound


What is electrolysis?

When electricity is passes through a molten or aqueous ionic compound, the compound is broken down and the process is called electrolysis


What Is reduced at the cathode when there's a group 1/2 metals present?


2H2O + 2e ---> 2OH- + H2

(If other metals then the metal is reduced.)
(Hydrogen if acid)


What is oxidised at the anode if the salt is a halide?


(Oxygen if sulfate or nitrate)
(Oxygen is alkali)


Kc - constant
What is the equation?

[C]c [D]d
[A]a [B]b



Risks of chlorine?

Toxic gas
Irritant to eyes, skin, respiratory system
Reacts with lungs to for, HCl which effects the tissues


How is chlorine transported?

Uses pressurised tank containers
In liquid to store more
If pressure or temp too high, the tanks has pressure release devices to vent the tank and releases Cl as a gas
The tank if made and lined with steel
Dry so doesn't react with anything


Uses of chlorine

Water treatment
Household bleach
Remove stains on clothing


What is atom economy and what is the equation?

It's the percentage of reactants that end up in the desired products

Atom economy = Mr of desired product / Mr of reactants x 100


How do u make hydrogen halides?

HCl = sodium chloride + sulfuric acid as it's not a strong enough reducing agent
HBr = sodium bromide + phosphoric acid as its a strong enough reducing agent to reduce sulfuric acid to sulfur dioxide
HI = sodium iodide + phosphoric acid as it reduces sulfur dioxide to hydrogen sulfide


What happens if:
Pressure increases
Temperature increases
Temperature decreases
Pressure decreases

Side with fewer gas moles
Endothermic direction
Exothermic direction
Side with more gas moles


If concentrations of :
Reactants increase
Reactants decrease
Products increases
Products decrease

The equilibrium moves to the
Products side
Reactants side
Reactants side
Products side


What is the trend in thermal stability and acidity as you go down the group?

Thermal stability decreases
HCl HBr HI are very acidic


What is the reaction with halogens and ammonia?

Glass rid dipped in ammonia solution and put it near halogen and a white cloud of ammonium halide is made.