Prototype of Chem Review Cards

Matter

Anything that has mass and occupies space.

Element

A substance that cannot be broken down into simpler chemical substances; made of one type of atom.

Compound

A substance composed of two or more elements chemically combined in a fixed ratio.

Homogeneous Mixture

A mixture that has a uniform composition and appearance throughout (e.g., salt water).

Heterogeneous Mixture

A mixture that is not uniform in composition; different parts are visible (e.g., salad).

Proton

A subatomic particle with a positive charge, found in the nucleus of an atom.

Neutron

A subatomic particle with no electrical charge, found in the nucleus of an atom.

Electron

A subatomic particle with a negative charge, located outside the nucleus.

Atomic Number (Z)

The number of protons in the nucleus of an atom; determines the element's identity.

Mass Number (A)

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

Isotope

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Dimensional Analysis

A mathematical method used to convert from one unit to another using conversion factors.

Significant Figures

The digits in a measurement that are known with certainty plus one estimated digit.

Accuracy

How close a measured value is to the actual or true value.

Precision

How close a series of measurements are to one another, regardless of the true value.

Meniscus

The curved upper surface of a liquid in a tube; always read from the bottom for volume measurements.

Physical Change

A change that alters a substance without changing its chemical identity (e.g., melting ice).

Chemical Change

A change that results in the formation of new chemical substances (e.g., rusting).