Chemistry Form 4 – Atomic Structure & States of Matter

Vocabulary flashcards covering key terms on the states of matter, kinetic theory, changes of state, atomic models, sub-atomic particles, and isotopes from Form 4 Chemistry notes.

Matter

Anything that has mass and occupies space.

Particle Theory of Matter

Explains that matter is made of tiny, discrete particles (atoms, molecules or ions).

Kinetic Theory of Matter

States that the particles in matter possess kinetic energy and are constantly moving.

Brownian Motion

Random movement of tiny particles (e.g., pollen) in a fluid, evidence for particle motion.

Solid

State of matter with closely packed, orderly particles that vibrate in fixed positions; strongest intermolecular forces and lowest kinetic energy.

Liquid

State of matter with close, disordered particles that slide past one another; moderate intermolecular forces and higher kinetic energy than solids.

Gas

State of matter with widely spaced, random particles moving freely; very weak forces and highest kinetic energy.

Melting (Fusion)

Change of state from solid to liquid when heat is absorbed.

Freezing (Solidification)

Change of state from liquid to solid when heat is released.

Boiling / Vaporization

Change of state from liquid to gas throughout the liquid when heat is absorbed.

Condensation

Change of state from gas to liquid when heat is released.

Sublimation

Direct change of state from solid to gas (or gas to solid) without passing through the liquid phase.

Melting Point

The fixed temperature at which a solid turns into a liquid at atmospheric pressure.

Boiling Point

The fixed temperature at which a liquid turns into a gas at atmospheric pressure.

Dalton’s Atomic Theory

Described atoms as tiny, indestructible spheres unique to each element.

Thomson’s Plum-Pudding Model

Proposed atoms are positive spheres with embedded negative electrons.

Rutherford’s Nuclear Model

Revealed a small, dense, positively charged nucleus with electrons orbiting around it.

Bohr Model

Suggested electrons move in fixed energy levels (shells) around the nucleus.

Chadwick’s Discovery

Identified the neutron, a neutral particle in the atomic nucleus.

Atom

Smallest unit of an element that retains its chemical properties.

Electron

Negatively charged sub-atomic particle found outside the nucleus.

Proton

Positively charged sub-atomic particle located in the nucleus.

Neutron

Neutral sub-atomic particle located in the nucleus.

Nucleus

Central region of an atom containing protons and neutrons.

Electron Shell (Energy Level / Petala)

Region around the nucleus where electrons of similar energy are likely to be found.

Proton Number (Atomic Number, Z)

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

Nucleon Number (Mass Number, A)

Total number of protons and neutrons in the nucleus.

Isotope

Atoms of the same element with identical proton numbers but different neutron numbers.

Valence Electron

Electron located in the outermost shell, involved in chemical bonding.

Iodine-131

Radioisotope used to destroy cancerous thyroid cells.

Cobalt-60

Radioisotope used for sterilising medical equipment and food by killing microorganisms.

Sodium-24

Radioisotope used to trace leaks in underground water or oil pipes.

Phosphorus-32

Radioisotope used to measure phosphate fertiliser uptake in plants.

Carbon-14

Radioisotope used in radiocarbon dating to estimate the age of archaeological artifacts.