Atoms and Atomic Theory Timeline

Fill-in-the-blank flashcards covering key concepts from the Atom/Atomic Theory Timeline lecture notes.

Democritus proposed that matter could not be divided into smaller pieces forever and called these particles __.

atomos

Aristotle proposed that matter was made of different amounts of the elements: earth, water, air, fire, and __.

ether

Dalton's first statement: Atoms are tiny, invisible __.

particles

Dalton's second statement: Atoms of one element are all the __.

same

Dalton's third statement: Atoms of different elements are __.

different

Dalton's fourth statement: Compounds form by __ atoms.

combining

Thomson’s plum pudding model describes atoms as a positively charged material with embedded __.

electrons

The center of the atom is called the __.

nucleus

Rutherford showed the nucleus contains positively charged particles called __.

protons

In Rutherford's gold foil experiment, most alpha particles passed through the foil, but a few were __.

deflected

Bohr proposed that electrons move around the nucleus in specific __, or shells.

shells

Chadwick discovered __, particles with no charge.

neutrons

The Modern Model (1932–) describes electrons moving around the nucleus in a __, and it is impossible to know where an electron is at any given time.

cloud

The Modern Model relies on the __ principle, stating that position and momentum cannot be known simultaneously.

uncertainty

The Greek word for indivisible, from which 'atom' is derived, is __.

atomos

John Dalton published the very first atomic theory in __.

1808

J.J. Thomson discovered the electron in __.

1897