Chapter 1 chem

Matter

Anything that has mass and takes up volume.

Composition

What something is made of.

Structure

How the components of a substance are arranged.

Atom

The fundamental unit of matter.

Element

A pure substance made of only one type of atom.

Compound

A substance composed of more than one element, bound in fixed ratios.

Molecule

Groups of atoms that bind tightly together and behave as a single unit.

Mixtures

Contain more than one substance, not bound in a fixed ratio.

Homogeneous Mixtures

Components mix evenly.

Heterogeneous Mixtures

Components do not mix evenly.

Physical Properties

Can be measured without changing the identity of the substance (e.g., mass, volume, temperature, color, hardness).

Physical Changes

Changes that do not alter the identity of a substance.

Chemical Properties

Can NOT be measured without changing the identity of the substance.

Chemical Changes

Changes that alter the identity of a substance; also called chemical reactions.

Potential Energy

Energy that is stored.

Kinetic Energy

The energy of motion.

Exothermic Change

A change that releases heat energy.

Endothermic Change

A change that absorbs heat energy.

Scientific Method

A systematic process for investigating phenomena and acquiring new knowledge.

Hypothesis

A tentative explanation that has not been tested.

Theory

An idea supported by experimental evidence.

Scientific Law

A statement that describes observations that are true in widely varying circumstances.