Chemical formulae of elements

Question 1

What is a formula?

Answer 1

A combination of symbols that indicates the chemical composition of a substance.

Question 2

What is a compound?

Answer 2

A substance formed by the chemical reaction of two or more elements.

Question 3

What are balanced symbol equations?

Answer 3

A chemical equation written using symbols and formulae of the reactants and products, so that the number of units of each element present is the same on both sides of the arrow.

Question 4

What is a chemical formula used to represent?

Answer 4

A chemical formula is used to represent an element or compound in balanced chemical equations.

Question 5

Why are formulae different?

Answer 5

Formulae differ, depending on the elements they represent.

Question 6

What determines the formulae of a substance?

Answer 6

The formulae for most elements is just their symbol, but there is a group of non-metals that exist as molecules that contain two atoms joined together. To show this, their formulae all have a subscript number 2 in them.

Question 7

What is a molecule?

Answer 7

A collection of two or more atoms held together by chemical bonds.

Question 8

Give some examples of non-metals which are written as molecules in their formulae and show how this is done

Answer 8

For example:
* Iodine, I₂
* Bromine, B₂
* Chlorine, C₂
* Fluorine, F₂
* Oxygen, O₂
* Nitrogen, N₂
* Hydrogen, H₂

Question 9

Give a mnemonic to remember the elements written as molecules

Answer 9

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