Explore the particles that make up atoms: protons, electrons, and electrons.

This lesson will illustrate that an atom is mostly empty space and has a positively charged, massive core (containing both protons and neutrons called the nucleus) surrounded by negatively charged electrons. It is 2 of 3 in the series...

The three basic particles that make up atoms are defined and illustrated.

This lesson will explain that protons are positively charged particles having a mass of one amu and are found in the nucleus of the atom. It is 2 of 3 in the series titled "Subatomic Particles: The Proton."

Slideshow looking at the history of models of the atom, including those proposed by John Dalton, J.J. Thomson, Ernest Rutherford, Niels Bohr, and James Chadwick. Discusses subatomic particles, including the numbers of protons, neutrons,...

This diagram shows a basic atom structure with an atom core, proton, neutron and electron.

This lesson will define an isotope and explain what happens if the number of neutrons in an atom changes. It is 9 of 9 in the series titled "Isotopes."

This lesson will introduce the subatomic particles and explain where they are located and how they interact. It is 3 of 7 in the series titled "Subatomic Particles."

This lesson will introduce the subatomic particles and explain where they are located and how they interact. It is 7 of 7 in the series titled "Subatomic Particles."

Learn what atomic number is, and what happens if the numbers of protons in an atom changes.

This lesson will explain that electrons are negatively charged particles with negligible mass and are found in pairs in orbitals surrounding the nucleus of an atom. It is 3 of 3 in the series titled "Subatomic Particles: The Electron."

This lesson will explain that neutrons are particles in the nucleus that have no charge and a mass of one amu. It is 2 of 3 in the series titled "Subatomic Particles: The Neutron."