Atomic Structure and Electron Shells (Video Notes)

Vocabulary flashcards covering basic atomic structure and electron shell concepts as described in the video notes.

Atom

The basic unit of matter; historically thought indivisible; consists of a nucleus and electrons.

Subatomic particle

Particles smaller than an atom, such as protons, neutrons, and electrons.

Proton

Positively charged subatomic particle located in the nucleus.

Neutron

Electrically neutral subatomic particle located in the nucleus.

Electron

Negatively charged subatomic particle that orbits the nucleus in electron shells.

Nucleus

Dense central part of the atom containing protons and neutrons.

Electron shell

Region around the nucleus where electrons are likely found; also called energy level or orbit.

Energy level

A fixed energy state for electrons; levels are quantized.

Orbit

Path around the nucleus that electrons were once thought to follow.

Bohr model

Early atomic model describing electrons in quantized orbits around the nucleus.

K shell

First electron shell (n=1) closest to the nucleus; capacity 2 electrons.

L shell

Second electron shell (n=2); capacity 8 electrons.

M shell

Third electron shell (n=3); capacity 18 electrons.

N shell

Fourth electron shell (n=4); capacity 32 electrons.

Maximum electrons in a shell

Given by 2n^2, where n is the shell number; e.g., K=2, L=8, M=18, N=32.

Valence electrons

Electrons in the outermost shell of an atom.

Neutral atom

An atom with equal numbers of protons and electrons; net charge zero.

Octet rule

Atoms tend to have eight electrons in their outer shell for stability.

Principal quantum number

The index n that designates which electron shell an electron occupies.

Energy level labeling

Electron shells are labeled K, L, M, N from the nucleus outward.

Electron configuration

Arrangement of electrons across shells according to capacity and rules.

Nucleus composition

Nucleus contains protons (positively charged) and neutrons (neutral).