The amount of matter in an object.

Two or more substances that are together in the same place but their atoms are not chemically bonded.

A neutral group of two or more atoms held together by covalent bonds.

The change in state from a solid to a liquid.

The temperature at which a substance changes from a solid to a liquid.

The sum of protons and neutrons in the nucleus of an atom.

The basic particle from which all elements are made; the smallest particle of an element that has the properties of that element.

A solid made up of particles that are not arranged in a regular pattern.

The average mass of all the isotopes of an element.

Vaporization that occurs at and below the surface of a liquid.

The temperature at which a liquid boils.

A principle that describes the relationship between the pressure and volume of a gas at constant temperature.

A principle that describes the relationship between the temperature and volume of a gas at constant pressure.

The force of attraction that holds two atoms together.

A change in which one or more substances combine or break apart to form new substances.

The study of the properties of matter and how matter changes.

A characteristic of a substance that describes its ability to change into different substances.

A substance made of two or more elements chemically combined in a specific ratio, or proportion.

Symbols that show the elements in a compound and the ratio of atoms.

A form of energy that is stored in chemical bonds between atoms.

A solid that is made up of crystals in which particles are arranged in a regular, repeating pattern.

A one- or two-letter representation of an element.

The ratio of the mass of a substance to its volume (mass divided by volume)

A substance that cannot be broken down into any other substances by chemical or physical means.

A change in which energy is absorbed.

A change in which energy is released.

The process by which molecules at the surface of a liquid absorb enough energy to change to a gas.

A tiny, negatively charged particle that moves around the outside of the nucleus of an atom.

A region of an atom in which electrons of the same energy are likely to be found.

Any substance that can flow.

The change in state from a liquid to a solid.

A state of matter with no definite shape or volume.

Elements in the same vertical column of the periodic table; also called family.

A system of measurement based on multiples of ten and an established measures of mass, length, and time.

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

The principle that the total amount of matter is neither created nor destroyed during any chemical or physical change.

A state of matter that has no definite shape but has a definite volume.

The change of state from a gas to a liquid.

The central core of an atom which contains protons and neutrons.

A small particle in the nucleus of the atom, with no electrical charge.

A horizontal row of elements in the periodic table.

An arrangement of the elements showing the repeating pattern of their properties.

Small, positively charged particles that are found in the nucleus of an atom.

The force pushing on a surface divided by the area of that surface.

A characteristic of a pure substance that can be observed without changing it into another substance.

A change that alters the form or appearance of a material but does not make the material into another substance.

A single kind of matter that is pure and has a specific set of properties.

A state of matter that has a definite shape and a definite volume.

The result of an inward pull among the molecules of a liquid that brings the molecules on the surface closer together; causes the surface to act as if it has a thin skin.

The change in state from a solid directly to a gas without passing through the liquid state.

How hot or cold something is; a measure of the average energy of motion of the particles of a substance.

The total energy of the motion of all the particles of an object.

The change of state from a liquid to a gas.

A liquid's resistance to flowing.

A measure of the force of gravity acting on an object.

The amount of space that matter takes occupies.

The number of protons in the nucleus of an atom.