Group 7 - The Halogens Flashcards
At room temperature what is the state and appearance of the group 7 elements?
Fluorine - pale yellow gas Chlorine - yellow/green gas Bromine - dark red/brown liquid Iodine - grey/black solid Astatine - black solid
What is the bonding in the group 7 elements?
Covalent bonds between diatomic atoms
What is the structure of the halogens?
Simple covalent (molecular)
What is the melting and boiling point in the halogens and why?
Low melting and boiling points because little energy is needed to break the weak London forces between the molecules
As you go down the group, how does boiling point change? Why is this?
Increases when going down the group because…
- There are more shells, so more electrons
- There are more/stronger induced dipole-dipole attractions between molecules
- More energy is needed to break the induced dipole-dipole attractions between the molecules
What is meant by the term oxidising power?
A measure of the strength with which a halogen atom (X) is able to attract and capture an electron to form a halide ion (X-)
What is oxidising power also the same as?
Reactivity of the halogen
Why does the oxidising power of the halogens decrease as you go down the group?
- More shells and atomic radius increases
- Greater shielding effect
- Weaker nuclear attraction
- Less able to attract and capture another electron into its outer shell
What are all displacement reactions also?
REDOX reactions
Define a displacement reaction
A reaction in which a more-reactive element displaces a less-reactive element from an aqueous solution of its halide ions
What colour will be shown if each of chlorine, bromine and iodine are:
dissolved in water
dissolved in organic solvent
Chlorine - pale green, pale green (slightly darker)
Bromine - orange, orange (darker)
Iodine - brown, purple
NOTE: Ions are colourless and atoms are coloured
