Electronic Structure of Atom, Periodic Table and Periodicity

Vocabulary flashcards covering the basics of atomic structure, sub-atomic particles, nuclear notation, and the postulates of Bohr's Model of the Hydrogen Atom.

Proton

A sub-atomic particle located in the nucleus with a positive charge of (+) and a relative mass of $1\,amu$.

Electron

A sub-atomic particle with a negative charge of (–) and a relative mass of $0.0005\,amu$, located in the volume containing electrons.

Neutron

A sub-atomic particle located in the nucleus with no charge and a relative mass of $1\,amu$.

Atomic number ($Z$)

The number of protons in the nucleus of an atom; in a neutral atom, it is also equal to the number of electrons.

Mass number ($A$)

The total number of protons plus the number of neutrons in the nucleus ($A = Z + N$).

Isotopes

Atoms of an element with the same number of protons but different numbers of neutrons, and therefore different mass numbers.

Planetary Model

Bohr’s model of the atom which proposes that electrons revolve around the nucleus in specific orbits or shells with a fixed radius.

Emission spectrum of Hydrogen

Four narrow bands of bright light produced when light from hydrogen gas, excited by electric current, is passed through a prism.

Ground State

The lowest energy level where an electron is in a stable state.

Excited State

A higher energy level where an electron is in an unstable state after absorbing photon energy.

Excitation

The process occurring when a photon's energy is equal to the energy difference between the initial and final energy levels, causing an electron to jump to a higher level.

Stationary Orbits

Fixed circular energy levels (denoted as $n = 1, 2, 3\text{ etc.}$) in which an electron revolves around the nucleus without changing energy.

Photon

A packet of light energy whose energy equals the difference between two energy levels when an electron moves from one orbit to another.

Quantized

The concept that the energy of an atom has a definite amount related to the position of its electrons.