Lecture Notes: Bohr Model, Electron Configuration, and Bonding (Lectures 3 & 4)

Vocabulary flashcards covering Bohr model subshells, electron configuration, reaction types, balancing, and bonding concepts from the notes.

Subshell (Bohr model)

A subdivision within an electron shell (e.g., 1s, 2s, 2p) where an s subshell holds 2 electrons and a p subshell holds 6 electrons in total across three orbitals; electrons fill in the order 1s → 2s → 2p.

Electron configuration order

The sequence in which subshells are filled (1s, 2s, 2p, 3s, 3p, …) to designate the arrangement of electrons around an atom.

Nitrogen electron configuration

1s2 2s2 2p3; total electrons = 7.

Irreversible reaction

A chemical reaction that proceeds in one direction only; represented with a single arrow.

Reversible reaction

A chemical reaction that can proceed in both forward and reverse directions; represented with a double-headed arrow.

Coefficient (in a chemical equation)

The number in front of a chemical formula that multiplies the molecules (and thus the atoms) in that formula.

Reactants

Substances on the left side of a chemical equation; the starting materials.

Products

Substances on the right side of a chemical equation; the substances produced.

Balanced chemical equation

An equation in which the number of each element is the same on both sides, achieved by adjusting coefficients.

Hydrogen peroxide decomposition (balanced equation)

2 H2O2 → 2 H2O + O2; an example of balancing a reaction.

Polar covalent bond

A covalent bond where electrons are shared unequally due to a difference in electronegativity, creating partial charges (e.g., O–H in water).

Electronegativity

The tendency of an atom to attract electrons in a bond; oxygen is highly electronegative.

Water molecule (H2O)

A molecule with polar covalent O–H bonds; the polarity allows hydrogen bonding between water molecules.

Hydrogen bond

A weak attraction between a hydrogen atom covalently bonded to a highly electronegative atom (like O) and another electronegative atom.

Nonpolar covalent bond

A covalent bond in which electrons are shared equally, leading to no permanent dipole (e.g., many C–H bonds in methane).

Methane (CH4)

A nonpolar molecule where carbon forms four covalent bonds with hydrogen, resulting in an overall even distribution of electrons.

Valence electrons

Electrons in the outermost shell; for oxygen, there are six valence electrons.