History of the Atomic Model

These flashcards cover key terminology from the history of the atomic model, including definitions of essential concepts and discoveries related to atomic structure and subatomic particles.

Atom

The smallest particle of an element that retains the properties of that element; electrically neutral.

Dalton's Atomic Theory

All elements are composed of atoms that are submicroscopic indivisible particles; atoms of the same element are identical.

Electron

The negatively charged subatomic particle discovered by J.J. Thomson; previously called a corpuscle.

Nucleus

The center of the atom composed of protons and neutrons; contains most of the atom's mass.

Proton

Positively charged subatomic particle discovered by Eugen Goldstein; has a mass of 1 amu.

Neutron

Subatomic particle with no charge discovered by Sir James Chadwick; mass is nearly equal to a proton (1 amu).

Isotope

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

Quantum Energy

The amount required to move an electron from its present energy level to the next higher one.

Half-Life

The time required for half of a sample of a radioactive isotope to decay.

Radioactive Isotope

An isotope that has an unstable nucleus and undergoes radioactive decay.

Atom

The smallest particle of an element that retains the properties of that element; electrically neutral.

Dalton's Atomic Theory

All elements are composed of atoms that are submicroscopic indivisible particles; atoms of the same element are identical.

Electron

The negatively charged subatomic particle discovered by J.J. Thomson; previously called a corpuscle.

Nucleus

The center of the atom composed of protons and neutrons; contains most of the atom's mass.

Proton

Positively charged subatomic particle discovered by Eugen Goldstein; has a mass of 1 amu.

Neutron

Subatomic particle with no charge discovered by Sir James Chadwick; mass is nearly equal to a proton (1 amu).

Isotope

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

Quantum Energy

The amount required to move an electron from its present energy level to the next higher one.

Half-Life

The time required for half of a sample of a radioactive isotope to decay.

Radioactive Isotope

An isotope that has an unstable nucleus and undergoes radioactive decay.

Atomic Number

The number of protons in the nucleus of an atom; defines the element.

Mass Number

The total number of protons and neutrons in an atom's nucleus.

Ion

An atom or molecule that has gained or lost one or more electrons, resulting in a net electrical charge.

Radioactivity

The spontaneous emission of radiation by an unstable atomic nucleus.