Dalton's Atomic Theory & Atomic Structure (Video Notes)

Vocabulary flashcards covering key terms from the notes on atoms, atomic theory, nucleus and subatomic particles, atomic numbers/mass, and basic periodic table group concepts.

Atom

The basic unit of matter; extremely small and retains identity in a chemical reaction; composed of a nucleus of protons and neutrons surrounded by electrons.

Dalton's atomic theory

The postulates: matter is made of atoms; atoms of a given element are identical; elements differ; compounds form from atoms in fixed ratios; chemical reactions rearrange atoms to form new substances.

Element

A substance whose atoms are identical to each other and different from atoms of other elements.

Compound

A material formed from atoms of two or more elements in fixed, definite ratios.

Chemical reaction

A process in which the atoms present in substances are rearranged to form new substances.

Subatomic particles

The particles that make up atoms: protons, neutrons, and electrons.

Nucleus

The central region of the atom containing protons and neutrons.

Proton

Positively charged subatomic particle with mass located in the nucleus.

Neutron

Electrically neutral subatomic particle with mass located in the nucleus.

Electron

Negatively charged subatomic particle with negligible mass that orbits the nucleus.

Atomic number

Number of protons in an atom; determines the element’s identity; in neutral atoms it equals the number of electrons.

Mass number (atomic weight)

Sum of protons and neutrons in the nucleus.

Neutral atom

An atom with equal numbers of protons and electrons.

Metals

Elements that conduct heat and electricity; are malleable and ductile.

Nonmetals

Elements that are insulators and poor conductors.

Metalloids (semimetals)

Elements with properties between metals and nonmetals; often semiconductors needing a stimulus to conduct.

Lanthanides

A group of rare earth metals in the periodic table.

Actinides

An actinide series of radioactive elements in the periodic table.

Alkali metals

Group 1A metals; typically +1 oxidation state; highly reactive.

Transition metals

Central block metals; can have various oxidation states.

Pnictogens

Group 15 elements; commonly exhibit a -3 oxidation state.

Halogens

Group 17 elements; commonly exhibit a -1 oxidation state.

Noble gases

Group 18 elements; chemically inert; have 0 charge in their valence shell under standard conditions.

Alkaline earth metals

Group 2 elements; commonly display a +2 oxidation state.

Chalcogens

Group 16 elements; commonly exhibit a -2 oxidation state.

Inert gases

Another term for noble gases; highly unreactive.