Subatomic particles and the atom

How do you calculate the mass number?

It is the number of protons plus the number of neutrons.

The symbol for the atomic mass number is

A

Electron

A subatomic particle that has a negative charge and that is found in the electron cloud.

Proton

A subatomic particle that has a positive charge and that is found in the nucleus.

Neutron

A subatomic particle that has no charge and that is found in the nucleus.

What determines the identity of an element?

The atomic number or number of protons in the nucleus.

The symbol for the atomic number is

Z

Which subatomic particle has a mass much smaller than the others?

an electron.

Isotopes are

atoms of the same element that have different numbers of neutrons; so same atomic number, but different mass numbers.

The volume or size of the atom is determined by the size of the

electron cloud.

The atomic number tells us

how many protons are in the nucleus; also how many electrons are in a neutral atom.

The mass of the atom is mostly determined by the mass of the

nucleus.

Which two subatomic particles each have a mass of approximately 1 amu?

protons & neutrons

When an isotope symbol is drawn

the mass number goes on top and the atomic number goes on the bottom.

An atomic mass unit (amu) is

1/12 the mass of a carbon-12 atom.

How are the atomic weights given on the periodic chart calculated?

By a averaging the masses of the isotopes, weighted by their percent abundances.