Elements from the sea Flashcards
What are halogens?
Group 7 elements are halogens. They are very reactive
What type of molecule is an F2 molecule?
Diatomic molecule
What is a diatomic molecule?
It is a molecule joined with a covalent bond between two of the same atom
e.g. Cl2
How do halogens achieve stability?
They react ionically with a metal to make a halide ion
Or they react covalently with another non metal
Describe the trend down group 7
They become darker in colour Melting and boiling points increase They change from gasses to liquids to solids down the group at room temperature They become less volitile They become less reactive down the group
Which is the most reactive halogen? and why?
Florine is the most reactive and it gets less reactive down the group
This is because as you go down the group, the atoms get larger and so the attraction to the outer electrons so reacting and attracting another electron is weaker
What is oxidisation and reduction?
Oxidisation is when electrons are lost by atoms
Reduction is when electrons are gained by atoms
What is a reducing and oxidising agent?
This is the atoms that causes the oxidisation or reduction
What is the oxidising agent and reducing agent and what was oxidised or reduced in the reaction:
2Na(s) + Cl2(g) ==> 2NaCl(s)
Sodium is oxidised
Chlorine is reduced
So the oxidising agent is the chlorine because it takes the electron and the sodium is the reducing agent because it gives away the electrons
What happens in this reaction and why?
Cl2 + 2KI == > ?
The products are:
2KCl + I2
This is because the more reactive halogen takes the place of the less reactive halogen
What is the ionic equation for:
Cl2 + 2KI ==> 2KCl + I2
And what is left out and why?
Cl2 + 2I- ==> 2Cl- + I2
Spectator ions are left out because they arn’t directly involved in the reaction and are unchanged from the reaction
What is the half equation for the reaction of:
Cl2 + 2KI ==> 2KCl + I2
What does this show about each atom?
Cl2 + 2e- ==> 2Cl-
2I- ==> I2 + 2e-
It shows what has been oxidised and reduced. Chlorine has been reduced and the iodine has been oxidised
What type of reaction is this?:
Cl2 + 2KI ==> 2KCl + I2
It is a displacement reaction or a redox reaction
What is the colour of Silver chloride?
White
What is the colour of Silver bromide?
Cream
What is the colour of silver iodide?
Pale yellow
What happens when you add ammonia to silver chloride?
It goes colourless
What happens when you add ammonia to silver bromide?
It becomes more colourless but still clearly white
What happens when you add ammonia to silver iodide?
It is unchanged because it is not soluble
What happens when silver ion is added to a halide ion?
It reacts and forms a solid silver halide precipitate
What happens in the reaction:
Mg(s) + CuO(s) ==> MgO(s) + Cu(s)
and what type of reaction is this?
Magnesium is oxidised because it gains oxygen and so electrons are given to the oxygen so electrons are lost.
Copper is reduced because it loses oxygen so it gains electrons back from the oxygen.
Copper is the oxidising agent
Magnesium is the reducing agent
It is redox reaction
What is an oxidising state?
This is a measure of how many electrons have been gained or lost in comparison to the unreacted element
Why is the oxidation state useful for?
Naming inorganic compounds
Deciding what has been oxidised and what has been reduced
Identifying the oxidising / reducing agent
Balancing redox equations
What are the usual oxidation states for: Oxygen Hydrogen Group 7 Aluminium Group 1 Group 2
Oxygen = -2 Hydrogen = +1 Group 7 = -1 Aluminium = +3 Group 1 = +1 Group 2 = +2