The proton determines the identity of an element.

Isotopes have the same number of protons but different numbers of neutrons.

Ions have a different number of electrons.

The average atomic mass of an element is the weighted average of the mass of the naturally occurring isotopes.

Nuclear fusion creates all elements heavier than hydrogen.

An atom is made up of protons, neutrons, and electrons.

• 1. Protons are positively charged and located in the nucleus.

  2. Neutrons are neutral and located in the nucleus.

  3. Electrons are negatively charged and located outside the nucleus.

The number of protons will never vary in the same element. If the proton number changes, the element changes.

The number of protons = atomic number

Mass number = protons + neutrons

Isotopes have different number neutrons which results in different mass numbers.

In a neutral atom, protons = electrons.

Ions form when electrons are gained or lost, creating a charged atom (an ion).

To calculate the average atomic mass for each isotope

• 1. Multiply (mass of isotope) x (percent abundance/100)

  2. Add answers for all isotopes together

The most abundant isotope will be closest in value to the average atomic mass.