The halogens and alkali metals Flashcards
What does the name ‘Halogen’ mean?
salt-producing.
The halogens are non-metallic elements with diatomic molecules. What does it mean to be diatomic?
It cannot be on it’s own - there has to be to atoms of it, making it a molecule. For example, flourine must always be written as F2
Describe the trend in the halogens.
As the molecules get larger towards the end of the group, the melting points and boiling points increase.
They become less reactive as you move down the group.
Explain the trend in the halogens in terms of melting/ boiling point.
The boiling and melting points get higher towards the bottom of the group because the molecules are larger, meaning there are stronger forces of electrostatic attraction and so require more energy to break them apart.
Explain the trend in the halogens in terms of reactivity.
The halogens are more reacitve at the top of the group because they are elements who wish to recieve an electron in order to become stable. The molecules at the top of the group are smaller, so the outer shell of electrons is closer to the positive attraction of the nucleus. This means that it will recieve an electron more easily because it will have a stronger force of electrostatic attraction to eh nucleus.
Which halogens are solid at room temperature?
Iodine and astatine.
What is the trend in the halogens in terms of colour?
They become darker in colour as they go down the group.
Give the colours of:
- Flourine
- Chlorine
- Bromine
- Iodine
- Flourine: yellow
- Chlorine: green
- Bromine: dark red
- Iodine: dark grey solid
What is formed when halogens react with hydrogen?
Give an example.
Hydrogen halides
For example:
Hydrogen (g) + Bromine (g) —> Hydrogen bromide (g)
What happens when hydrogen chloride gas dissociates in water?
When hydrogen chloride is dissolved in water the HCL molecules split up into H+ ions and Cl- ions. This process is called dissociation.
The solution that is formed is hydrochloric acid.
What is methylbenzene?
An organic solvent
What happens when hydrogen chloride gas is put in methylbenzene?
It does not dissociate into H+ and Cl- ions.
This means there are no H+ ions produced and it is not acidic.
