2.2 - Group 7 Flashcards
What are the group 7 elements
The elements in group 7 are known as the halogens.
These are fluorine, chlorine, bromine, iodine and astatine
What are the halogens
These elements are non-metals that are poisonousreact with metals to form salts
What is the reactivity like for halogens
All halogens have similar reactions as they each have seven electrons in their outermost shell
What colour is Florine at room temp
Yellow gas
What colour is Chlorine at room temp
yellow gas
What colour is Bromine at room temp
Red - brown liquid
What colour is iodine at rt
purple black solid
What are the characteristic of fluorine gas
Very reactive poisonous gas
What are the characteristic of Chlorine gas
Reactive poisonous and dense gas
What are the characteristic of Bromine liquid
Dense red - brown volatile liquid
What are the characteristic of iodine solid
Shimmery crystalline solid sublimes to form a purple vapour
What is the melting and boiling point trend in the halogens
The melting and boiling points of the halogens increase as you go down the group
This is due to increasing intermolecular forces as the atoms become larger, so more energy is required to overcome these forces
What is the trend for colours in the halogens
The colours of the halogens also change as you descend the group - they become darker
What is the trend for reactivity in the halogens
The halogens decrease in reactivity moving down the group, but they still form halide salts with some metals including iron
The rate of reaction is slower for halogens which are further down the group such as bromine and iodine
What is a displacement reaction?
A halogen displacement reaction occurs when a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide
What happens when you add chlorine solution to a colourless potassium bromide
The solution becomes orange as bromine is formed or
The solution becomes brown as iodine is formed
Chlorine is above bromine and iodine in group 7 so it is more reactive
Chlorine will displace bromine or iodine from an aqueous solution of the metal halide:
What is a spectator ion
The metal ion in a halogen reaction does not do anything doesn’t react.
Explain the reactivity of the halogens
Reactivity of group 7 non-metals decreases as you go down the group
As you go down group 7, the number of shells of electrons increases, the same as with all other groups
Halogensform negative ions
This means that the increased distance from the outer shell to the nucleus as you go down a group makes the halogens become less reactiveless atraction between the nucleus and the shells
Fluorine is the smallest halogen, which means its outermost shell is the closest to the positive nucleus of all the halogen
Therefore, the ability to attract an electron is strongest in fluorine making it the most reactive
As you move down the group, the forces of attraction between the nucleus and the outermost shell decreases
This makes it harder for the atoms to gain electrons as you descend the group
Therefore, the halogens are less reactive the further down the group you go
What are redox reactions?
When oxidation and reduction occours
What happens in a displacement reaction in terms of oxidation and reduction?
the more reactive element acts as the oxidising agent it takes electrons away from the less reactive element reducing itself
