Chemistry revision

Question 1

Definition of atomic number

Answer 1

The number of protons in an atom.

Question 2

Definition of Mass number

Answer 2

The number of protons and neutrons in an atom.

Question 3

Definition of Isotopes

Answer 3

Atoms of the same element (same number of protons) but with a different number of neutrons.

Question 4

Definition of relative atomic mass (Ar)

Answer 4

The average mass of an atom compared to 1/12th the mass of carbon-12.

Question 5

Definition of atom

Answer 5

An atom is the smallest part of an element.

Question 6

Definition of molecule

Answer 6

A molecule is made of a fixed number of atoms covalently bonded together.

Question 7

How to calculate the Empirical formula

Answer 7

1. find the mass of each element
2. find the Ram of each element
3. find the moles of each element
4. find the ratio of moles for each element
5. write down the empirical formula

Question 8

How to calculate the Molecular formula

Answer 8

1. Find the Mr of the compound
2. Find the Mr of the empirical formula
3. Number of empirical formula units
4. empirical formula X empirical formula units
5. Write down the Molecular formula