Atomic Structure and the Periodic Table Flashcards

Grade 9 · Science · Flashcards

Review key vocabulary for atomic structure and periodic table organization with these 12 flashcards.

Flashcards

Atom: Smallest unit of an element that retains its chemical properties; made of protons, neutrons, and electrons.
Proton: Positively charged particle found in the nucleus; its count equals the atomic number.
Neutron: Neutral particle found in the nucleus; contributes to mass number but not to charge.
Electron: Negatively charged particle orbiting the nucleus in energy shells; involved in bonding.
Atomic Number: The number of protons in an atom; uniquely identifies each element on the periodic table.
Mass Number: Total protons + neutrons in the nucleus of a specific atom.
Isotope: Atoms of the same element with different neutron counts — same atomic number, different mass number.
Valence Electrons: Electrons in the outermost energy level; control how atoms bond with each other.
Period: Horizontal row of the periodic table; elements in the same period have the same number of electron shells.
Group (Family): Vertical column of the periodic table; elements share the same number of valence electrons.
Alkali Metals: Group 1 elements with 1 valence electron; very reactive, soft metals (e.g., lithium, sodium, potassium).
Noble Gases: Group 18 elements with full outer shells (8 valence e⁻); nearly unreactive (e.g., helium, neon, argon).