group 7 elements Flashcards
fluorine
very reactive, poisonous yellow gas
chlorine
fairly reactive, poisonous, dense green gas
bromine
dense, poisonous, red-brown volatile liquid
iodine
dark grey crystalline solid or a purple vapour
what do all halogens exist as?
molecules (pairs of atoms)
what is the trend in reactivity going down the group?
it decreases
why does the reactivity decrease as you go down the group?
the outer shell is further from the nucleus so the attraction is weaker meaning it is harder to gain an extra electron
what is the trend in melting and boiling points going down the group?
they increase
what is the trend in atomic mass going down the group?
it increases
how many electrons are on the outer shell?
7
what compounds do halogens form?
covalent and ionic
what ion do halogens form?
1-
when will a displacement reaction occur?
between a more reactive halogen and the salt of a less reactive one
what is the ion form of a halogen called?
halide
use of fluorine
toothpaste
uses of chlorine
kill bacteria
bleach
swimming pools
uses of bromine
camera films
bromine water
uses of iodine
antiseptic
tests for starch
displacement reaction
a reaction when a more reactive element displaces a less reactive element from its compound
5 characteristics of halogens
-7 electrons in outer shell
-coloured vapours
-diatomic molecules
-form ionic compounds
-form molecular compounds
