Atomic Number, Atomic Mass

Front

Subatomic particles with a negative charge

Back

Electrons are subatomic particles that carry a negative charge.

Front

What is the atomic number of an element?

Back

The atomic number is the number of protons in the nucleus of an atom, which determines the element's identity.

Front

What is the atomic mass of an element?

Back

The atomic mass is the weighted average mass of an element's isotopes, measured in atomic mass units (amu).

Front

How many protons are in a neutral atom of an element with atomic number 7?

Back

A neutral atom with atomic number 7 has 7 protons.

Front

What are isotopes?

Back

Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.

Front

How do you calculate the number of neutrons in an atom?

Back

To find the number of neutrons, subtract the atomic number from the mass number: Neutrons = Mass Number - Atomic Number.

Front

What is the mass number of an atom?

Back

The mass number is the total number of protons and neutrons in the nucleus of an atom.

Front

What is the charge of a neutron?

Back

Neutrons have no charge; they are neutral particles.

Front

What is the charge of a proton?

Back

Protons carry a positive charge.

Front

How many neutrons does calcium (atomic number 20, mass number 40) have?

Back

Calcium has 20 neutrons (40 - 20 = 20).