Fundamental Particles

Proton (+ charge)

Positively charged particle found in the atomic nucleus.

Discovery of Proton

Discovered by Eugene Goldstein.

Role of Proton

Determines the atomic number (Z), which defines the element.

Proton Composition

Made of two 'up' quarks and one 'down' quark.

Neutron (0 charge)

Uncharged particle found in the atomic nucleus.

Discovery of Neutron

Discovered by James Chadwick in 1932.

Nuclear Force

Holds protons and neutrons together within the nucleus.

Neutron Composition

Made of one 'up' quark and two 'down' quarks.

Electron (- charge)

Negatively charged particle that surrounds the atom’s nucleus.

Discovery of Electron

Discovered by J. J. Thomson in 1897.

Role of Electrons

Determines the chemical properties of the atom.

Chemical Reactions

Involve sharing or exchanging electrons.

Nucleus

Central part of an atom, composed of protons and neutrons.

Role of Nucleus

Contains most of an atom’s mass.

Discovery of Nucleus

Discovered by Ernest Rutherford in 1911.

Nucleons (Proton & Neutron)

Found inside the nucleus.

Composition of Nucleons

Made of quarks, held together by gluons.

Primary Difference Between Protons and Neutrons

Electric charge.

Ions

Formed when an atom gains or loses an electron.

Cation (+)

Atom loses an electron, becoming positively charged.

Anion (-)

Atom gains an electron, becoming negatively charged.