Question

How do you write formulas and names for the following elements?

Barium and oxygen:

Sodium and nitrogen:

Beryllium and bromine

Answer 1

In general the elements take the symbol based on their first letter often (not always) in English, except where that is already taken in which case a second lower case letter is added.

Explanation:

Thus barium is Ba (B is boron)

Oxygen is O

Sodium is Na (named after the Latin natrium)

Nitrogen is N (explaining why sodium couldn’t have that letter)

Beryllium is Be and finally,

Bromine is Br.

Regarding formulas you need to know the valency of the element (the number of electrons, or equivalent ‘spaces’ in its outer shell of electrons) to predict how many atoms of each element will bond successfully.

`2Ba + O_2 rarr 2BaO` as they both have a valency of 2.

`6Na + N_2 rarr 2Na_3N` as sodium has a valency of 1 and nitrogen, 3.

`Be + Br_2 rarr BeBr_2` as beryllium has valency of 2 and bromine 1.

This (http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway/chemical_concepts/fundamentalrev5.shtml) gives a fuller explanation!