Atomic Structure and Historical Atomic Models

Vocabulary flashcards covering the key historical atomic models, fundamental subatomic particles, and key figures from the physics lecture transcript.

Atom

The smallest particle of an element that cannot be divided or broken by chemical means, serving as the fundamental building block of matter.

Atomos

The Greek word meaning indivisible or not to be cut, from which the word atom is derived.

Greek's Atom Concept

An ancient theory stating that all matter is composed of four basic substances (Earth, Water, Air, Fire) modified in various proportions by four basic essences (wet, dry, hot, cold).

Dalton's Atom

An atomic model proposed in 1808 by John Dalton, stating that elements are composed of identical atoms with hooks and eyes to account for chemical combinations.

Thomson's Atom

Also known as the Plum Pudding Model, proposed by J.J. Thomson in the late 1890s, which described the atom as negative electric charges (plums) embedded inside a shapeless mass of uniform positive electrification (pudding).

Bohr's Atom

An atomic model developed by Niels Bohr in 1913 that pictured a miniature solar system with negatively charged electrons revolving in fixed, well-defined orbits or energy levels around a small, dense, positively charged nucleus.

Nucleus

The positively charged region at the center of an atom consisting of tightly packed protons and neutrons.

Nucleons

The collective term for the subatomic particles located within the nucleus, namely protons and neutrons.

Protons

Subatomic particles located in the nucleus carrying one unit of positive electric charge with a mass of $1.00728\,\text{amu}$.

Neutrons

Neutrally charged subatomic particles located in the nucleus with a mass of $1.00867\,\text{amu}$.

Electrons

Very small subatomic particles circulating outside the nucleus in defined shells, carrying one unit of negative electric charge with a mass of $0.000549\,\text{amu}$.

Dmitri Mendeleev

A Russian scholar who showed that arranging elements in order of increasing atomic mass revealed a periodic repetition of similar chemical properties, leading to the creation of the first periodic table of the elements.