G. C. E. (A/L) Chemistry: Unit 1 Atomic Structure

A series of flashcards covering essential vocabulary and concepts related to atomic structure, based on G.C.E. Chemistry curriculum.

Matter

The physical material of the universe; anything that has mass and occupies space.

Atomic theory

A set of principles that describes the nature of atoms as the fundamental building blocks of matter.

Atomos

Greek word meaning "indivisible"; refers to the concept that matter is composed of indivisible particles.

Dalton's first postulate

Elements are made out of extremely small, indivisible particles called atoms.

Cathode rays

Streams of invisible radiation emitted from the cathode in a cathode ray tube; consist of negatively charged particles.

J.J. Thomson

British scientist who discovered the electron and proposed the 'plum pudding' model of atomic structure.

Electron charge-to-mass ratio (e/m ratio)

The ratio of the charge of an electron to its mass, calculated by Thomson; found to be 1.76 × 10^8 C/g.

Plum pudding model

Thomson's model of atomic structure where electrons are embedded in a positively charged 'soup'.

Canal rays

Streams of positively charged particles observed in gas discharge tubes, later identified as protons.

Ion (cation/anionic)

A charged particle formed when an atom gains or loses electrons.

Isotopes

Atoms of the same element that have different numbers of neutrons.

Mass number

The total number of protons and neutrons in the nucleus of an atom.

Effective nuclear charge (Z_eff)

The net positive charge experienced by an electron in a multi-electron atom, accounting for shielding.

Electron configuration

A representation of the distribution of electrons in an atom's orbitals.

Pauli Exclusion Principle

No two electrons in an atom can have the same set of four quantum numbers.

Hund's Rule

Electrons will fill degenerate orbitals singly first, before pairing up.

Electronegativity

The ability of an atom in a molecule to attract electrons, with values defined on the Pauling scale.