Appendix A: Chemistry Basics - Atomic Structure and Periodic Table

Vocabulary flashcards covering fundamental chemistry topics including subatomic particles, isotopic notation, hydrogen isotopes, atomic weight calculations, IUPAC periodic table groups, electronic structure blocks, and subshell capacities.

Atomic Mass Unit (u)

A unit of mass defined as $1/12$ the mass of one atom of carbon-12, equal to $1.6605 \times 10^{-24}\,\text{g}$.

Proton

A subatomic particle in the nucleus with a charge of $+1$, a mass of $1.00731\,\text{u}$ ($1.67262 \times 10^{-27}\,\text{kg}$), and a mass number contribution of $1$.

Neutron

A subatomic particle in the nucleus with a charge of $0$, a mass of $1.00871\,\text{u}$ ($1.67495 \times 10^{-27}\,\text{kg}$), and a mass number contribution of $1$.

Electron

A subatomic particle located outside the nucleus with a charge of $-1$ and a mass of $0.00054860\,\text{u}$ ($9.1095 \times 10^{-31}\,\text{kg}$) that defines the atomic sphere size and participates in chemical reactions.

Atomic Radius Ratio

The ratio of the radius of an atom's nucleus to the radius of the entire atom, which is approximately $1$ to $100{,}000$.

Atomic Number ($Z$)

The total number of protons in the nucleus of an atom, which determines the chemical identity of an element.

Mass Number ($A$)

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

Isotopic Notation

A symbolic representation written as ${}_{Z}^{A}\text{E}$, where $\text{E}$ is the element symbol, $A$ is the mass number, and $Z$ is the atomic number.

Isotopes

Atoms of the same element containing identical numbers of protons ($Z$) but differing numbers of neutrons, resulting in different mass numbers ($A$).

Deuterium (${}^2\text{H}$)

An isotope of hydrogen consisting of $1$ proton, $1$ neutron, and $1$ electron, possessing a natural abundance of $0.0156\,\%$.

Tritium (${}^3\text{H}$)

An isotope of hydrogen consisting of $1$ proton, $2$ neutrons, and $1$ electron, with a natural abundance of about $1$ atom per $10^{18}$ ${}^1\text{H}$ atoms.

Heavy Water (${}^2\text{H}_2\text{O}$)

A toxic form of water containing deuterium atoms rather than standard hydrogen, with a molar mass of $20\,\text{g\,mol}^{-1}$ compared to $18\,\text{g\,mol}^{-1}$ for regular water (${}^1\text{H}_2\text{O}$).

Natural Abundance

The percentage of each individual isotope present in a naturally occurring sample of an element.

Atomic Weight

The weighted average mass of all naturally occurring isotopes of an element, calculated using isotopic masses and fractional abundances.

IUPAC

International Union of Pure and Applied Chemistry, which recognizes $118$ known elements organized into $18$ groups.

Hydrogen (Periodic Table Position)

An element displayed in both Group $1$ and Group $17$ because its chemical properties resemble both group types.

Electronic Blocks

The four main divisions of the periodic table categorized by electronic subshell structure: s-block, p-block, d-block, and f-block.

Helium (Block Exception)

An element located above Ne in Group $18$ that is explicitly not classified as a p-block element.

Alkali Metals

The group of chemical elements residing in Group $1$ of the periodic table.

Alkaline Earth Metals

The group of chemical elements residing in Group $2$ of the periodic table.

Pnictogens

The specific group designation for Group $15$ elements in the p-block.

Chalcogens

The specific group designation for Group $16$ elements in the p-block.

Halogens

The specific group designation for Group $17$ elements in the p-block.

Noble Gases

The specific group designation for Group $18$ elements in the p-block.

s Subshell Capacity

An electronic subshell present starting at main shell level $n=1$ that holds up to $2\,e^{-}$.

p Subshell Capacity

An electronic subshell present starting at main shell level $n=2$ that holds up to $6\,e^{-}$.