Wednesday, 09/02 key points

A set of vocabulary flashcards covering key concepts from the lecture notes on atomic structure, isotopes, ions, particle properties, density, and symbol notations.

Atomic Number ($Z$)

The total number of protons in an atom, calculated as mass number minus total number of neutrons ($Z = A - N$).

Mass Number ($A$)

The sum of protons and neutrons in an atom ($\text{Mass Number} = \text{Protons} + \text{Neutrons}$). It is always a whole integer representing a specific single isotope and does not appear on the periodic table.

Isotopes

Atoms of the same element that differ in the number of neutrons, but contain the same number of protons (e.g., $^{28}\text{Si}$ and $^{29}\text{Si}$, or Uranium-240).

Atomic Mass (Atomic Weight)

The weighted average mass of all naturally occurring isotopes of an element, based on their natural percent abundance, which appears on the periodic table.

Formation of Ions

The process where neutral atoms become ions via the loss or gain of electrons, with $\text{Charge} = \text{Protons} - \text{Electrons}$.

Cation

A positively charged ion that is formed when a neutral atom loses 1 or more electrons (e.g., neutral hydrogen losing its 1 electron to become $\text{H}^+$).

Anion

A negatively charged ion that is formed when a neutral atom gains 1 or more electrons (e.g., neutral oxygen gaining 2 electrons to become an oxide anion, $\text{O}^{2-}$, with 10 electrons).

Formal Ionic Charge Notation

Notation format where the number is written before the charge sign (e.g., $2-$ or $2+$).

Oxidation Number Notation

Notation format where the number is written after the charge sign (e.g., $-2$ or $+2$).

Full Nuclear Symbol

A symbol format that displays an element's mass number ($A$), atomic number ($Z$, often omitted), element symbol ($E$), and charge.

AMU

Atomic mass units, a very small unit used to express atomic mass.

Protons

Positively charged particles located in the nucleus of an atom that determine element identity, chemical behavior, and stability.

Electrons

Negatively charged particles located outside the nucleus of an atom.

Neutrons

Neutral charged particles located in the nucleus of an atom.

Density

A physical property calculated as mass divided by volume ($\text{Density} = \frac{\text{Mass}}{\text{Volume}}$).