M2Q2: Protons, Neutrons, and Electrons — Vocabulary

Vocabulary flashcards covering subatomic particles, nucleus, atomic mass unit, elementary charge, atomic number, mass number, isotopes, ions (cations and anions), neutral atoms, ionic charges, and common element groups.

Proton

Positively charged subatomic particle located in the nucleus; mass ≈ 1.007 amu; number of protons (Z) defines the element.

Neutron

Electrically neutral subatomic particle in the nucleus; mass ≈ 1.008 amu; adds to mass but does not change the element.

Electron

Negatively charged subatomic particle outside the nucleus; mass ≈ 0.0005486 amu; balances charge and drives chemical behavior.

Nucleus

Dense, positively charged center of an atom containing protons and neutrons.

Atomic Mass Unit (amu)

Unit of mass for atoms; 1 amu ≈ 1.6605×10^-24 g; roughly the mass of a proton or neutron; 1/12 the mass of a carbon-12 atom.

Elementary Charge (e)

Magnitude of the electric charge carried by a proton (positive) or electron (negative); e ≈ 1.602×10^-19 coulombs.

Atomic Number (Z)

Number of protons in the nucleus; determines the element's identity.

Mass Number (A)

Total number of protons and neutrons in the nucleus; A = Z + N.

Isotope

Atoms of the same element (same Z) with different numbers of neutrons, giving different mass numbers.

Ion

Charged atom formed when electrons are gained or lost; positive ions are cations, negative ions are anions.

Cation

Positively charged ion formed when an atom loses electrons.

Anion

Negatively charged ion formed when an atom gains electrons.

Neutral Atom

An atom with equal numbers of protons and electrons; no net electric charge.

Ion Charge

Charge on an ion resulting from loss or gain of electrons; common states include +1, +2, and -1.

Alkali Metals

Group 1 metals that typically form +1 ions and are highly reactive.

Alkaline Earth Metals

Group 2 metals that typically form +2 ions.

Transition Metals

Metals in the d-block with multiple possible oxidation states, often forming +1, +2, or +3 ions.

Halogens

Group 17 nonmetals that typically form -1 ions when reacting.

Noble Gases

Group 18 elements that are inert and usually do not form ions; oxidation state effectively 0.