Atomic Theory and Atom Basics Vocabulary

Flashcards covering key terms, subatomic particles, isotopes, and historical atomic models based on lecture notes.

Protons

Positively charged subatomic particles located in the nucleus of an atom.

Neutrons

Subatomic particles with zero charge $(0)$ located inside the nucleus of an atom.

Electrons

Negatively charged subatomic particles located outside the nucleus in the electron cloud.

Atomic Number

The characteristic value of an element based on its number of protons.

Mass Number

The whole-number sum of the protons and neutrons in an atom, which is not found on the periodic table.

Nuclear Symbols

Notation that gives both the mass number and atomic number for a specific element.

Ions

An atom or group of atoms that has a positive or negative charge because it has gained or lost electrons.

Isotopes

Atoms of the same element that have the same number of protons but a different number of neutrons.

Protium

The most common isotope of hydrogen, containing $1\text{ p}^+$ and $0\text{ neutrons}$.

Deuterium

An isotope of hydrogen containing $1\text{ p}^+$ and $1\text{ n}^0$.

Tritium

An isotope of hydrogen containing $1\text{ p}^+$ and $2\text{ n}^0$.

Atomic Mass

The weighted average mass of all the naturally occurring isotopes of an element.

Democritus

The philosopher who coined the term "atom" and believed all matter was made of indivisible particles.

Aristotle

The philosopher who believed the concept of the atom was false and proposed that matter was a continuous substance without fundamental units.

John Dalton

The scientist (1766-1844) who proposed an experiment-based atomic theory stating that matter is composed of small, indivisible atoms that combine in simple whole-number ratios.

J.J. Thomson

The scientist who used cathode ray tubes to discover the electron, calculate its charge-to-mass ratio, and propose the plum pudding atomic model.

Robert Millikan

The scientist who performed the Oil Drop Experiment, determined the charge of an electron, and calculated its mass as $m_e = 9.11 \times 10^{-28}\,\text{g}$.

Ernest Rutherford

The scientist who performed the Gold Foil Experiment and discovered the nucleus, showing it is extremely dense and takes up very little space.

Niels Bohr

The scientist who created the quantum model of the atom, proposing that electrons travel only in specific allowed circular orbits.