Science 8th grade notes

Atom

The basic building block of all matter, composed of a nucleus containing protons and neutrons, surrounded by electrons.

Proton

A subatomic particle with a positive charge found in the nucleus of an atom.

Neutron

A subatomic particle with no charge (neutral) found in the nucleus of an atom.

Electron

A subatomic particle with a negative charge that orbits the nucleus of an atom.

Element

A type of atom characterized by the number of protons in its nucleus, known as the atomic number.

Atomic Number

The number of protons in the nucleus of an atom, defining the element.

Periodic Table

An organized chart of elements based on atomic number, symbol, name, and atomic mass.

Valence Electrons

Electrons in the outermost energy level of an atom, determining its reactivity.

Energy Levels

Spherical layers around the nucleus where electrons are found, with smaller levels closer to the nucleus.

Bohr Model

A visual representation of the arrangement of electrons in energy levels around the nucleus of an atom, following specific patterns.