Lab 1 – Atomic Structure and the Periodic Table (Vocabulary Flashcards)

Atom

The fundamental unit of matter composed of protons, neutrons, and electrons.

Subatomic Particle

A particle smaller than an atom; includes protons, neutrons, and electrons.

Proton

Positively charged particle in the nucleus; number of protons equals the atomic number.

Neutron

Neutral particle in the nucleus; contributes to atomic mass and can vary among isotopes.

Electron

Negatively charged particle orbiting the nucleus in energy shells; determines chemical properties.

Nucleus

Dense central core of an atom containing protons and neutrons; holds most of the mass.

Atomic Number

Number of protons in an atom’s nucleus; identifies the element.

Atomic Mass Unit (AMU)

Unit used to express atomic and molecular masses; approximately the mass of one proton or neutron.

Electron Shell

Energy level around the nucleus where electrons reside; each shell holds a set number of electrons.

Valence Shell

Outermost electron shell; contains electrons involved in bonding and ion formation.