Amorphous solid: A solid consisting of molecules that are arranged randomly.

Archimedes Principle: The buoyant force on a submerged object is equal to the weight of the fluid that is displaced by the object.

Atom: The smallest particle of a particular element.

Atomic mass: Protons and neutrons have roughly 1836 times more mass than an electron. The mass of an atom is due to the number of protons and neutrons in its nucleus. The atomic mass of an element is a relative number that is closely related to the number of protons plus the average number of neutrons.

Avogadro’s number: The number of kilograms of an element that is numerically equal to its atomic mass contains a fixed number of atoms. This number is known as Avogadro’s number and equals 6.02 x10²³.

Bond: The net result of forces of attraction and repulsion between atoms, ions or molecules.

Buoyancy: Upward force acting on an object that is partially or completely immersed in a fluid.

Compound: A substance whose molecules or ionic structures consist of atoms of two or more elements that are chemically bonded.

Compressibility: The ability of a substance to change its volume as the pressure on it changes.

Crystal: A solid structure consisting of atoms or ions arranged in a regular pattern.

Density: A property of a substance that indicates the ratio of mass to volume.

Density: The ratio of the mass of an object or material to its volume.

Density: Mass per unit volume. [Units: kg/m³ or g/cm³]

Element: A material consisting of one particular type of atom. The various known elements are listed on Page …. of the notes for this lesson.

Elasticity: The ability of an object or material to return to its original shape after forces that cause deformation have been removed.

Elastic limit: The degree of compression or elongation beyond which a material will not return to its original shape.

Electron: A negatively charged particle that is found outside the nucleus. Electrons move about in orbitals or electron clouds around the nucleus.

Fluid: A material that can flow. Usually a gas or a liquid.

Gas: A substance that is in the gaseous state expands to fill its container. In this state the forces of attraction between particles are weak. The particles can move freely.

Heat: Energy in motion.

Heat capacity: The amount of energy needed to increase the temperature of a material by a certain amount. The specific heat capacity refers to a certain mass of the material.

Heat of fusion: The quantity of energy needed to change a certain amount of a substance in the solid phase to liquid at the same temperature.

Heat of vaporization: The quantity of energy needed to change a certain amount of a substance in the liquid phase to gas at the same temperature.

Hooke’s law: The extension of a spring is directly proportional to the force acting on it.
The spring will return to its original position after the force is removed provided that its elastic limit has not bee exceeded.

Ion: Atoms are electrically neutral having equal numbers of protons and electrons. An ion can consist of an atom with one or more missing electrons. Ions can also consist of combinations of atoms with an overall positive or negative charge resulting from the loss or gain of electrons.

Isotope: Atoms of the same element can differ in the number of neutrons in their nuclei. Atoms of the same element with different numbers of neutrons are called isotopes.

Kinetic: Relating to movement. The Kinetic Theory explains behavior of substances in relation to the rate of movement of particles and the forces of attraction and repulsion between these.

Liquid: A substance that flows. In the liquid state material can change shape but (under the influence of gravity) is confined to the bottom of the container.

Molecule: The smallest particle of a substance. Molecules can consist of any number of atoms. Some proteins have molecules with many thousands of atoms. The bonds that hold atoms together result primarily from the sharing of electrons between atoms.

Mixture: A mixture consists of different substances that are not chemically bonded together. Mixtures can be separated by physical means whereas compounds require chemical reactions to separate the components.

Neutron: A neutral particle located in the nucleus of an atom.

Nucleus: Each atom has a nucleus that is surrounded by electrons. Virtually all of the mass of an atom is concentrated in the protons and neutrons that make up the nucleus.

Pascal's Law: When there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container.

Phase: A form of matter that can be solid, liquid, gas or plasma. Phases are often called states and visa versa.

Plasma: In the plasma phase, which is usually at high temperatures, matter consists of positively charged ions and free electrons.

Pressure: The force acting on an area. (Force per unit area) [Units: N/m² or Pa.]

Proton: A positively charged particle located in the nucleus of an atom.

Solid: A state in which the material has a definite shape and volume. A solid does not easily change shape.

Solid: A substance that has a definite volume and shape.

State: A property used to describe an object or material: Solid, liquid, gas
or plasma.