Chemistry Lecture Notes: Periodic Table, Electron Structure, and Metal Reactivity

Vocabulary flashcards covering periods, groups, alkali metals (Li, Na, K), metal reactivity with water, and the quantum structure of electrons (shells, subshells, orbitals, and related principles).

Period

A horizontal row on the periodic table; corresponds to a principal electron shell and there are seven periods.

Group

A vertical column on the periodic table; elements in the same group share similar properties (e.g., Group 1 contains the alkali metals).

Alkali metal

A highly reactive metal in Group 1 that has one valence electron; Li, Na, and K are classic examples; they react vigorously with water to produce hydrogen gas and metal hydroxide.

Metal

In this context, an element on the left side of the periodic table that is typically a solid, malleable, and a good conductor of electricity.

Sodium metal (Na)

Metallic sodium with no net charge; highly reactive with water; stored under oil to prevent reaction with air and moisture.

Sodium ion (Na+)

Sodium that has lost its outer electron, forming a positively charged ion found in salts such as NaCl; different from metallic sodium.

Lithium metal (Li)

Metallic lithium; reacts with water; Li+ is formed in solution and has medical/therapeutic uses.

Potassium metal (K)

Metallic potassium; more reactive with water than lithium; reacts vigorously and may ignite, forming KOH in solution.

Hydrogen gas (H2)

Gas produced when alkali metals react with water; released during the reaction.

Metal hydroxide (MOH, e.g., LiOH, NaOH, KOH)

Hydroxide product formed when alkali metals react with water; consists of a metal cation and OH− in solution.

Reactivity trend in Group 1

Reactivity increases down the group as the outer valence electron is farther from the nucleus and more easily lost.

Quantization

In quantum mechanics, energy and electron locations come in discrete steps; electrons occupy fixed energy levels rather than a continuum.

Shell (principal energy level)

A major electron energy level designated by the principal quantum number n (n = 1 to 7); shells correspond to distance from the nucleus and energy.

Subshell

Subdivision of a shell associated with shapes (s, p, d, f); defines the set of orbitals within a shell.

Orbital

A region within a subshell where electrons are likely to be found; each orbital can hold two electrons; orbitals have specific orientations (s: 1, p: 3, d: 5).

Two electrons per orbital

Pauli exclusion principle; each orbital holds a maximum of two electrons with opposite spins.

Electron address (shell, subshell, orbital)

A description of an electron's location; shell = city, subshell = street, orbital = house number; together determine energy and position.