deducing formulae

Question 1

what is the formula of aluminium sulfide

Answer 1

step 1
finding the group number for each element
aluminium -3
sulfur would be 2 as it is a non-metal so it is 8-6=2
step 2
swap the numbers

so the answer would be Al2S3

Question 2

what is the formula of calcium bromide?

Answer 2

step 1
write the formulae of the ions Ca+ and Br-
step 2
balance the charges. we need two Br- to balance on Ca2+
step 3
write the formulae with the metal ion first CaBr3

Question 3

what are state symbols

Answer 3

gas (g), liquid (l), solid(s)

Question 4

what is an ionic equation

Answer 4

an equation showing only those ions and molecules taking part in the reaction.

Question 5

what are spectator ions

Answer 5

ions which do not take part in a reaction.