Quantum Numbers and Atomic Structure

Vocabulary flashcards covering quantum numbers, electron configuration, and periodic table concepts from the provided notes.

Quantum Numbers

A set of numbers used to describe the trajectory, size, shape, and orientation of an electron’s orbit within an atom; effectively the electron’s address.

Principal Quantum Number (n)

Symbol n; describes orbital size and energy; indicates the electron’s shell; values 1,2,3,… (n ≠ 0).

Azimuthal Quantum Number (l)

Symbol l; describes orbital shape and subshell; for a given n, l ranges from 0 to n−1 (e.g., n=3 allows l=0,1,2).

Magnetic Quantum Number (ml)

Symbol ml; describes orbital orientation in space; values range from −l to +l (e.g., for l=1: ml = −1, 0, +1).

Spin Quantum Number (ms)

Symbol ms; indicates electron spin direction; values +1/2 or −1/2.

Aufbau Principle

Electrons fill the lowest-energy orbitals first before occupying higher-energy ones.

Orbital

Region of space where there is a high probability of finding an electron; each orbital holds up to two electrons with opposite spins.

Subshell

A set of orbitals with the same n and l values; labeled s, p, d, f.

s Subshell

l = 0; contains 1 orbital and up to 2 electrons.

p Subshell

l = 1; contains 3 orbitals and up to 6 electrons.

d Subshell

l = 2; contains 5 orbitals and up to 10 electrons.

f Subshell

l = 3; contains 7 orbitals and up to 14 electrons.

Electron Configuration

Notation showing the distribution of electrons among orbitals in an atom, typically following Aufbau, Pauli, and Hund’s rules.

Periodic Table

Organized array of elements by increasing atomic number; exhibits periodic law; elements in the same group have similar properties.

Atomic Number

Number of protons in the nucleus; defines the identity of the element and equals the number of electrons in a neutral atom.

Average Atomic Mass

Weighted average mass of an element’s isotopes; includes protons, neutrons, and electrons.

Period (Periodic Table)

Horizontal row in the periodic table; corresponds to principal energy levels.

Group (Periodic Table)

Vertical column in the periodic table; elements in a group share similar properties.

Metals

Lustrous, malleable elements that generally conduct heat and electricity well.

Nonmetals

Elements with properties unlike metals; typically poor conductors.

Metalloids

Elements with properties intermediate between metals and nonmetals.

Orbitals Capacity

s holds 2 electrons; p holds 6; d holds 10; f holds 14 electrons.

Orbitals per Sublevel

s: 1 orbital; p: 3 orbitals; d: 5 orbitals; f: 7 orbitals.

Energy Levels (n)

Principal energy levels, designated by n, with allowed values from 1 to 7.

Energy Sublevels

Sublevels within a principal energy level labeled s, p, d, f.

Order of Filling Orbitals

Electron orbitals fill in a specific order (Aufbau diagram) based on increasing energy.

Electron Configuration Notation (example)

Notation such as Na: 1s2 2s2 2p6 3s1; may be abbreviated using noble-gas cores.