Elements, Atoms, and the Periodic Table

Vocabulary flashcards covering key definitions, atomic theories, subatomic particles, periodic table structure, and electron configurations.

Chemistry

The study of matter, which encompasses anything that has mass and volume.

Periods

The horizontal rows of the periodic table, arranged by increasing atomic number.

Groups

The vertical columns of the periodic table containing elements that exhibit similar chemical reactivity.

Dalton's solid sphere model

An 1803 atomic model proposed by John Dalton that imagined atoms as solid, indivisible spheres.

Thomson's plum pudding model

A 1904 atomic model that introduced tiny negatively charged electron "plums" surrounded by positively charged "pudding".

Rutherford's nuclear model

A 1911 atomic model introducing a central nucleus containing protons and neutrons, surrounded by electrons.

Bohr's planetary model

A 1915 atomic model introducing fixed orbitals that contain electrons at discrete, quantized energy levels.

Schrodinger's electron cloud model

A 1926 atomic model that refined circular electron orbits into three-dimensional electron clouds.

Proton ($p^+$)

A positively charged subatomic particle with a charge of +1 and a mass of $1\,amu$, located inside the nucleus, that determines the identity of an element.

Neutron ($n^0$)

A neutral subatomic particle with a charge of 0 and a mass of $1\,amu$, located inside the nucleus, that helps hold the nucleus together and determines the isotope.

Electron ($e^-$)

A negatively charged subatomic particle with a charge of -1 and a mass of $\sim 0\,amu$, located in orbitals outside the nucleus, responsible for chemical reactivity and bonding.

Atomic number ($Z$)

The total number of protons present in the nucleus of an atom.

Atomic mass ($A$)

The sum of the number of protons and neutrons in the nucleus of an atom.

Isotopes

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

Shells

Energy divisions that broadly describe the energy and relative size of orbitals, denoted by the principal quantum number $n$.

Subshells

Classifications (s, p, d, and f) that describe the shape of orbitals within an electron shell.

Aufbau principle

A rule for electron filling stating that elements fill the lowest energy orbitals first.

Pauli exclusion principle

A quantum mechanical principle stating that a single orbital can fit a maximum of only two electrons.

Hund's rule

A rule stating that when multiple orbitals have the same energy, each receives one electron before any orbital receives a second paired electron.

Electronic configuration

A notation writing out subshells with superscripts indicating the number of electrons occupying each subshell.

Condensed electronic configuration

An abbreviated electron configuration written using the elemental symbol of the preceding noble gas in brackets followed by the remaining subshells.