2.1.1 Atomic Structure

Relative masses AND relative charges of protons, neutrons and electrons?

Proton: Relative mass = 1 Relative charge = +1

Neutron: Relative mass = 1 Relative charge = 0

Electron: Relative mass = 1/2000 Relative charge = -1

Atomic number

Number of protons in the nucleus

Mass number

Total number of protons and neutrons in the atom

Isotope

Isotopes are atoms of the same element with the same number of protons, but different numbers of neutrons

Why do isotopes have similar chemical properties but slightly varying physical properties?

Isotopes have similar chemical properties because they have the same electronic structure. They may have slightly varying physical properties because they have different masses.

Relative Isotopic mass

= The mass of an atom of an isotope, compared to 1/12th of the mass of an atom of carbon-12.

Relative atomic mass

= the weighted mean mass of an atom of an element, compared to 1/12th of the mass of an atom of carbon-12.

Relative molecular mass (Mr)

= the mean mass of a molecule, compared to 1/12th of the mass of an atom of carbon-12.

State the formulas for these molecular ions:

1. Hydroxide

2. Nitrate

3. Ammonium

4. Sulfate

5. Carbonate