Front

What is the nucleus of an atom?

Back

The nucleus is a tiny but very dense, positively charged portion of the atom that holds most of the atomic mass.

Front

How many protons does an aluminium atom have?

Back

An aluminium atom has 13 protons.

Front

What is the mass number of an atom?

Back

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

Front

What is atomic mass?

Back

Atomic mass is the weighted average of the nuclear particles: protons + neutrons of all isotopes of an element.

Front

What must be the same for atoms of the same element?

Back

Atoms of the same element must always have the same number of protons.

Front

Define atomic number.

Back

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

Front

What are electrons?

Back

Electrons are negatively charged subatomic particles that orbit the nucleus of an atom.

Front

What is an isotope?

Back

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

Front

What is the charge of a neutron?

Back

A neutron has no charge; it is neutral.

Front

What is the role of protons in an atom?

Back

Protons determine the atomic number and identity of an element.