GROUP 7 Flashcards
What are group 7 elements called?
Halogens
What are halogens?
Diatomic non-metals with colored vapours
What is fluorine at room temperature?
Pale yellow gas
What is chlorine at room temperature?
A green gas
What is bromine at room temperature?
Red-brown liquid
What is iodine at room temperature?
A black solid
What happens to atomic radii down group 7, and why?
Atomic radii increases - This is because each element down the group has one more filled outer energy level than the one above. This means there is a greater distance between outer electrons and positive nuclei.
Define electronegativity
A measure of the tendency to attract a pair of electrons in a covalent bond
What does electronegativity depend on?
- Nuclear charge
- Distance between the nucleus and outer energy level electrons
- Shielding
What happens to electronegativity down group 7 and why?
Decreases - As shielding and atomic radii increases, there is less of an attraction between the positive nuclei and electrons,so it is harder to gain them.
What is unexpected about the F-F bond?
It is unexpectedly weak, compared with the rest of the halogens. The small size of the atom leads to repulsion between non-bonding electrons because they are so close together.
What happens to melting and boiling points down group 7?
Increase - As larger atoms have more electrons, so more van der waals, so greater energy is required to overcome these bonds
How do halogens react?
They react usually by gaining electrons to form negative ions. These reactions are redox reactions.
What happens to oxidizing ability down group 7 and why?
Decreases - Oxidizing agents must be able to accept electrons, and further down the group atomic radii and shielding increases so the attraction between positive nuclei and electrons is weaker, so it becomes harder to oxidize as electrons cannot be easily gained.
How do halogens react with metal halides?
Via displacement reactions - the more reactive halogen displaces the less reactive halogen
