Structure of Atom Model

Quick Answer: The Structure of Atom Model is a school science display showing the three particles that make up an atom: protons and neutrons packed into a central nucleus, and electrons moving around it. A key labels each particle, so students learn their charges and locations and connect them to atomic number and mass number.

Protons, Neutrons and Electrons

The listing image of the structure of atom model shows a colourful cluster of proton and neutron balls at the centre, electron beads on an orbit around it, and a key reading P = proton, N = neutron, e = electron. The emphasis is on the particles themselves, which makes it the natural first model in an atomic structure unit.

Each particle has its own charge and mass. Protons carry a positive charge and neutrons none, and each has a mass of about one atomic mass unit, so together they account for nearly all of an atom’s mass. Electrons carry a negative charge equal in size to the proton’s but have only about 1/1836 of its mass. A neutral atom has equal numbers of protons and electrons; the number of protons is the atomic number, and protons plus neutrons give the mass number.

The model also tells a story of discovery. J.J. Thomson identified the electron in 1897 and pictured the atom as a positive sphere studded with electrons. Ernest Rutherford’s gold foil experiment, published in 1911, showed that the positive charge is concentrated in a tiny nucleus, Niels Bohr placed the electrons in fixed orbits in 1913, and James Chadwick discovered the neutron in 1932. Students can use the model to explain what each experiment added.

Applications

• Introducing protons, neutrons and electrons
• Teaching atomic number, mass number and neutral atoms
• Tracing the history of atomic models from Thomson to Chadwick
• Explaining how ions and isotopes differ from neutral atoms

Specifications

Care & Handling

• Handle it by the frame or base and do not press on the nucleus cluster.
• Wipe with a soft dry cloth and keep it away from water and solvents.
• Store it in a closed cupboard to keep dust off the small balls.

Why Choose LabEquip

Teachers usually buy this model to open the atomic structure chapter, before students meet specific elements. LabEquip lists it in the STEM kits range with the Orbit of Atom Model for the electron-shell stage of the topic and the Isotopes of Hydrogen Model for isotopes. Ask about quantities through the contact page.

Frequently Asked Questions

What are the three particles in an atom?

Protons, neutrons and electrons. Protons and neutrons are found in the nucleus at the centre, and electrons move in the space around the nucleus.

What are the charges of the subatomic particles?

A proton has a positive charge, an electron has a negative charge of the same size, and a neutron has no charge. In a neutral atom the numbers of protons and electrons are equal, so the charges cancel.

Where is most of the mass of an atom?

In the nucleus. Protons and neutrons each have a mass of about one atomic mass unit, while an electron has less than a thousandth of that, so the electrons add very little.

How big is the nucleus compared with the atom?

Tiny. The nucleus is very roughly a hundred thousand times smaller across than the atom. If an atom were the size of a cricket stadium, its nucleus would be about the size of a pea at the centre.

What is the difference between atomic number and mass number?

The atomic number is the number of protons and identifies the element. The mass number is the total number of protons and neutrons in the nucleus.

Who discovered the parts of the atom?

J.J. Thomson discovered the electron in 1897, Ernest Rutherford showed in 1911 that atoms have a small positive nucleus and later identified the proton, and James Chadwick discovered the neutron in 1932.

Last Updated: September 2026