Determination of formulae - 3.2 - (1)

Question 1

Molecular formulae: What are some compounds made up of?

Answer 1

small units called molecules - two or more atoms are held together by covalent bonds

Question 2

Molecular formulae: What is the molecular formula?

Answer 2

the number of atoms of each element in a molecule

Question 3

Empirical formula: What is the empirical formula?

Answer 3

the simplest whole-number ratio of atoms of each element in a compound

Question 4

Empirical formula - What is the empirical formula important for?

Answer 4

substances that do not exist as molecules - this includes metals, and some non-metals (e.g. carbon - C, and silicon - Si)

Question 5

Empirical formula - What do these substances form?

Answer 5

giant crystalline structures of atoms or ions

Question 6

Empirical formula - What would it be impossible to base?

Answer 6

a formula on the actual number of atoms or ions as the numbers would go into billions and billions –> it would also vary depending on the size of the crystal

Question 7

Empirical formula - Define the empirical formula in simple terms

Answer 7

the ratio of atoms or ions in the structure and they will always be the same

Question 8

More relative masses - What do some compounds exist as?

Answer 8

simple molecules (e.g. water - H2O, and carbon dioxide - CO2)

Question 9

More relative masses - What do other compounds exist as?

Answer 9

giant crystalline structures (e.g. all ionic compounds)

Question 10

More relative masses - What are two terms needed for?

Answer 10

relative mass - one for simple molecules and another for giant structures

Question 11

Relative molecular mass - What does relative molecular mass consist of?

Answer 11

it compares the mass of a molecule within the mass of an atom of carbon-12

Question 12

Relative molecular mass - How can you easily calculate a relative molecular mass?

Answer 12

by adding together the relative atomic masses of the elements making up a molecule