Anything that has mass and takes up space.

A measure of how much space an object takes up.

The physical form in which a substance exists, such as solid, liquid, or gas.

A characteristic of a material that can be observed or measured without changing the substance itself.

The amount of matter in an object, usually measured in grams or kilograms.

A state of matter that has a definite shape and volume, where the particles are closely packed together.

A state of matter that has a definite volume but takes the shape of its container, where particles are close but can move past one another.

A state of matter that has no definite shape or volume, where particles are far apart and move freely.

The smallest unit of a substance that retains all the properties of that substance.

The act of closely watching or monitoring something to gather information.