MATTER AND MATERIALS: The Particle Model of Matter & Density

Vocabulary flashcards covering key terms from the notes on matter, the particle model, phases, diffusion, phase changes, expansion/contraction, and density.

Matter

Everything around us that has mass and volume; made of particles; the smallest particle for an element is an atom, and for a compound is a molecule.

Atom

The smallest particle of an element.

Molecule

The smallest particle of a compound; formed when two or more atoms join.

Particle Model of Matter

Theory that matter consists of tiny particles with energy that move, have spaces between them, and interact via forces of attraction and repulsion.

Phase

A state of matter (solid, liquid, gas; plasma as a fourth phase) characterized by particle arrangements and energies.

Plasma

A fourth phase of matter; a highly energized gas where electrons are freed; common in stars and some industrial processes.

Kinetic Theory of Matter

Part of the model describing that particles have energy, move constantly, and that there are spaces between them with forces of attraction/repulsion.

Crystal Lattice

A regular, repeating pattern in which particles are arranged in a solid.

Solids

Particles have very little energy, vibrate in place, are densely packed with no spaces, have strong attraction, and form crystal lattices.

Liquids

Particles have some energy, can move in a disordered manner, have small spaces between them, with moderate attraction/repulsion and no set pattern.

Gases

Particles have lots of energy, move fast, occupy large distances with large spaces between them, and move in a disorderly, unpatterned way.

Diffusion

Movement of particles from high concentration to low concentration due to random motion.

Phase Change

Transition between solid, liquid, and gas caused by heating (adds energy) or cooling (removes energy).

Expansion

Increase in size/volume of a substance when heated as particles gain energy and move apart.

Contraction

Decrease in size/volume when cooled as particles lose energy and move closer together.

Ice-Water Density Anomaly

Ice is less dense than liquid water between 0 and 4 °C, so ice floats; water expands when freezing.

Density

Mass per unit volume; a unique property of a substance; measured in g/cm³ or kg/m³.

p (rho)

Symbol for density in the equation p = m/V.

Mass

Amount of matter in an object; usually measured in grams (g).

Volume

Amount of space an object occupies; measured in cm³ or m³.

Density Formula

Density equals mass divided by volume: p = m / V.

Floating and Sinking (Density)

An object floats if its density is less than the surrounding liquid; sinks if greater.

Common Densities

Typical densities: Air ~0.0013 g/cm³; Cork ~0.25 g/cm³; Petrol ~0.8 g/cm³; Cooking oil ~0.93 g/cm³; Water 1.00 g/cm³; Glass ~2.5 g/cm³; Granite ~2.7 g/cm³; Aluminium ~2.7 g/cm³; Stainless steel ~7.8 g/cm³; Lead ~11.4 g/cm³; Gold ~19.3 g/cm³.

Expansion Joints

Gaps in buildings, roads, and bridges to accommodate expansion and contraction of materials.

Sunkink

A kink in railway rails caused by expansion when expansion joints are not present or insufficient.