1.11 understand the terms atomic number, mass number, isotopes and relative atomic mass (Ar)

ATOMIC NUMBER:

- Is the total number of protons in the nucleus of an atom.

MASS NUMBER:

- Is the total number of protons and neutrons in the nucleus of an atom.

ISOTOPES:

- Are the different forms of the same element. They have the same amount of protons but different amounts of neutrons. For example:
Carbon-12 has 6 protons, 6 electrons, and 6 neutrons
Carbon-14 which has 6 protons, 6 electrons, and 8 neutrons.

RELATIVE ATOMIC MASS (Ar):

- It is the measure of the mass of one atom of the element. Basically it is how heavy different atoms are based on the scale of an atom of carbon-12.
- It is the average mass of all isotopes of an element.
- To calculate it:
1. Write the formula.
2. Write how many of each atom.
3. Write in relative atomic mass(Ar) for each type of atom.
4. Calculate the total mass for each element.
5. Add up total mass for the compound.