Atoms, Orbitals, and Bonding - VOCAB Flashcards (Video Notes)

Vocabulary flashcards covering the key concepts from the lecture notes on electron arrangements, energy shells, orbitals, electronegativity, and the three main types of chemical bonds (covalent, ionic, metallic).

Bioluminescence

Light produced by chemical reactions in living organisms; in deep-sea creatures it helps attract mates, attract prey, or evade predators through camouflage.

Energy shell (electron shell)

A region around the nucleus that holds electrons at specific energy levels; each shell can hold a maximum of 2n^2 electrons.

Orbital

A 3-D space within an energy shell where electrons reside; each orbital can hold up to 2 electrons and is labeled by type (s, p, d, f).

Subshell (s, p, d, f)

Divisions within an energy shell that describe sets of orbitals with similar shapes; determine how electrons are arranged in a shell.

Valence electrons

Electrons in the outermost shell of an atom that determine bonding behavior and chemical reactivity.

Valence shell

The outermost electron shell of an atom.

Octet rule

Atoms tend to gain, lose, or share electrons to have eight electrons in their valence shell for stability.

Electronegativity

The measure of an atom’s ability to attract electrons in a chemical bond; varies across the periodic table and influences bond type.

Electronegativity trend

Higher in elements toward the top-right of the periodic table; lower toward the bottom-left.

CHNOPS

The six most common bioelements—Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur—that predominantly form covalent bonds in biology.

Covalent bond

A bond formed when atoms share electrons to fill their valence shells.

Ionic bond

A bond formed by transfer of electrons from a less electronegative atom to a more electronegative one, creating ions held together by electrostatic attraction.

Metallic bond

A bond in metals where electrons are shared collectively in a ‘sea’ of delocalized electrons among many atoms.

Polar covalent bond

A covalent bond in which electrons are shared unequally, creating partial charges on atoms.

Nonpolar covalent bond

A covalent bond in which electrons are shared equally between atoms.

Electronegativity difference threshold

Difference in electronegativity around 0–1.7 typically forms covalent bonds; greater than about 1.7 tends to form ionic bonds.

Noble gas

Elements with full valence shells and typically little tendency to bond (e.g., Neon has 8 valence electrons and is inert).

Group (column) on the periodic table

Elements in the same group have similar chemistry because they have the same number of valence electrons.

2n^2 rule

The maximum number of electrons in the nth energy shell equals 2n^2 (n = shell number).

Atomic number

The number of protons in the nucleus; in a neutral atom this equals the number of electrons.

Molecule

Two or more atoms held together by covalent bonds; the group of atoms forms a distinct chemical species.

Molecular orbital

A region formed when atomic orbitals combine in a molecule, describing the spatial distribution of electrons and bonding.

Oxygen valence electrons

Oxygen has 6 valence electrons and needs 2 more to complete its valence shell.

Hydrogen valence electrons

Hydrogen has 1 valence electron and needs 1 more to complete its valence shell (2 total).

Neon (noble gas)

A noble gas with a full valence shell (8 electrons) and typically does not form bonds.

Electron shell capacities (1st–4th)

Capacities: 1st shell = 2, 2nd shell = 8, 3rd shell = 18, 4th shell = 32 electrons.

Sorbital shapes (S, P, D, F)

S orbitals: spherical; P orbitals: peanut-shaped; D orbitals: diamond-shaped; F orbitals: more complex shapes.

Ionic compound example (NaCl)

Sodium chloride forms via transfer of an electron from Na to Cl, creating ions that attract to form an ionic bond.