# A helium atom image - accessible

Image shows a large light coloured circle that represented an atom. An atom has no net charge, is the smallest physically dividable particle and has a size of 10-10m. Inside the circle is a dotted line that represents the electron orbits. Located on the dotted line are two blue circles with a letter e in the middle representing electrons. Electrons have a single negative charge, are a fundamental particle type lepton and have a size of less than 10-14m. In the middle of the atom are two brown circles and two red circles. The brown circles represent neutrons. Neutrons have no charge, are subatomic particles type Hadron and have a size of 10-15m. The red circles represent protons. Protons have a single positive charge, are subatomic particles type Hadron and have a size of 10-15m. Inside each proton and neutron are three small circles connected by a yellow lightning bolt. The yellow lightning bolt represents a gluon. Gluons are subatomic particles that cause quarks to interact and cause protons to interact with neutrons in the atomic nuclei. Each proton contains two circles with a u in them and one with a d in it. Each neutron has two circles with a d in them and one circle with a u in it. The circles with a u inside them represent up quarks. Up quarks have a positive charge that is two thirds the strength of the charge of a proton are a fundamental particle type quark and have a size of 10-19m. Down quarks have a negative charge that is one third the strength of the charge of a neutron, are a fundamental particle type quark and have a size of 10-19m.