C2 Group 7 Elements Flashcards
What are group 7 elements known as?
Halogens
What type of elements make up group 7?
Non metals
List the elements in group 7 (5)
Fluoride Chlorine Bromine Iodine Astatine
How many electrons are in the outer shell of all group 7 elements?
7
Complete the sentence
All group 7 elements have 7 electrons in their outer shells, so they all have similar ……
…..chemical properties
Halogens exist as diatomic molecules. Explain
Sharing one pair of electrons in a covalent bond gives both atoms a full outer shell
What happens to the melting and boiling points as you go down group 7 elements?
They increase
What is fluorine like at room temperature and pressure?
Highly reactive, toxic, pale yellow gas
What is chlorine like at room temperature and pressure?
Fairly reactive, poisonous, green gas
What is bromine like at room temperature and pressure?
Poisonous, red-brown liquid, which gives off an orange vapour at room temperature
What is iodine like at room temperature and pressure?
A dark grey crystalline solid which gives off a purple vapour when heated.
Why do the melting and boiling points increase as you go down group 7?
Due to the increase in the number of electrons in each atom as you go down the group.
Why is more energy needed to overcome the molecules as you go down group 7?
More electrons mean there are greater intermolecular forces between the molecules, so more energy is needed to overcome them.
What happens to the reactivity as you go down group 7?
The halogens become less reactive.
Why do the halogens become less reactive as you move down group 7?
It gets harder to attract the extra electron to fill the outer shell when it’s further away from the nucleus
What are the salts formed from a reaction between halogens and alkali metals called?
Metal halides
See p 24 for equations for halogens reacting with alkali metals
All reactions between group 1 and group 7 elements follow this pattern - make sure you can write equations for any of them.
Why do halogens higher up group 7 react more vigorously with alkali metals?
Because they are more reactive.
Why do all halogens have a similar reaction?
Because they have the same number of electrons in their outer shells.
Why does knowing how one halogen reacts help you to predict how other halogens will react?
Because they have similar reactions, since all halogens have the same number of electrons in their outer shell.
To know what type of salt is formed by a halogen, just replace ‘ine’ with what?
‘ide’
What type of salt does fluorine form?
Fluoride salts
What type of salt does iodine form?
Iodide salts
The melting point of chlorine (Cl2) is -101.5 degree C.
Predict whether bromine (Br2) would be a solid, a liquid or a gas at -101.5 degree C. Explain your answer.
(2 marks)
Bromine would be a solid at this temperature (1 mark)
The melting point of the halogens increase as you go down the group, so at the melting point of chlorine, bromine would still be solid (1 mark)
Writ a balanced symbol equation for the reaction between sodium metal (Na) and iodine (I2)
2Na + l2 -> 2Nal
1 mark for correct reactants and products, 1 mark for correctly balanced equation
