Atomic Models and Atomic Structure

Vocabulary flashcards highlighting historical atomic theories, key experiments, subatomic particle characteristics, and atomic math formulas from the lecture notes.

Atomos

The term used by Democritus to describe the smallest, indivisible piece of matter.

Democritus's Atomic Theory

The theory that matter could not be divided forever and that atoms were made of the same material but differed in shape and size.

John Dalton

A scientist who concluded that all elements are composed of atoms, where atoms of the same element are alike and atoms of different elements are different.

Plum Pudding Model

J.J. Thompson’s atomic model which describes the atom as a positively charged substance with negative electrons scattered throughout.

Cathode Ray Experiment

The experiment conducted by J.J. Thompson to develop his atomic model.

Earnest Rutherford

The scientist who performed the gold foil experiment and discovered that the atom has a dense positive center called the nucleus and is mostly empty space.

Bohr Model

A model based on an emission experiment stating that electrons move in definite orbits at certain distances, where those closer to the nucleus have less energy.

Electron Cloud Model

Erwin Schrodinger's model developed through math probability, stating that atoms do not move in fixed orbits and are surrounded by a region of electrons.

Protons

Subatomic particles located in the nucleus with a positive charge of $+1$ and a mass of $1\,amu$.

Neutrons

Subatomic particles located in the nucleus with a neutral (no) charge and a mass of $1\,amu$.

Electrons

Subatomic particles with a negative charge that are located in the electron cloud outside the nucleus.

Atomic Number

The value that identifies the number of protons in an atom.

Mass Number

The sum of the protons and neutrons in an atom: $\text{Proton} + \text{neutron} = \text{mass of atom}$.

Neutral Atom

An atom where the number of protons is equal to the number of electrons.

Calculation for Neutrons

$\text{mass number} - \text{atomic number} = \text{neutrons}$.

Bohr Model Energy Levels

The capacity of electron shells: first level = $2$ electrons, second = $8$ electrons, third = $18$ electrons, and fourth = $32$ electrons.

Ion

An atom with a charge, calculated using the formula $\text{Charge} = \text{protons} - \text{electrons}$.

Cation

An atom that has lost one or more electrons, resulting in a positive charge.

Anion

An atom that has gained one or more electrons, resulting in a negative charge.