Physical Science Unit One Key Terms

Alloy

a mixture of metals (or metal +nonmetal) designed for more potent or improved properties. Example: Brass (copper +zinc).

Atom

The fundamental particle of an element. It is made of subatomic particles called protons, neutrons, and electrons. 

Atomic Mass

The average weight of one atom of an element is derived by adding the number of protons and neutrons within the element and its isotopes.

Atomic Number

The number of protons in an atom of a given element. No two elements have the same atomic number.

Chemical change

A change that occurs when substances interact to form new substances with different properties. Also known as a chemical reaction. Examples: burning, rotting.

Chemical formula

A code that tells us what a substance is made of. Example: CaCO3 for Calcium carbonate.

Chemical name

The spelled-out name of a chemical. Example: Calcium carbonate.

Chemical property

A property that describes how a substance interacts or reacts with other substances - examples: flammability, reactivity.

Chemical reaction

The process by which substances interact to form a new substances.

Chemistry

The study of substances and how they interact.

Colloid

A mixture with medium-sized particles that do not settle out and scatter light (the Tyndall effect). Examples: milk, fog.

Common name

What people often call a substance. Example: chalk for calcium carbonate.

Denstiy

A physical property that measures the amount of mass in a given volume. 

Element Symbol

A chemical symbol element. If one letter, it is capitalized; if two letters, the first is capitalized and the second is lowercase.

Elements

The basic building materials of matter.

Families (Groups)

The vertical columns elements on the periodic table. Elements in a family have similar but not identical properties. 

Heterogeneous Mixture

A mixture where parts are not evenly distributed and the different substances are visible is an example of salad or orange juice with pulp.

Homogeneous Mixture

A mixture where substances are evenly distributed and look uniform throughout. Examples: salt, water, air.

Insoluble

Describes a substance that cannot dissolve in a solvent, for example, sand in water. 

Isotope

A version of an element with the same atomic number but a different number of neutrons.

Kinetic Molecular Theory (KMT)

The theory explains that the phases of matter depend on the kinetic energy and arrangement of particles.

Mass

The amount of matter in a substance is measures using a scale. 

Mass number

The total number of neutrons and protons in an atom.

Matter

Anything that has mass and takes up space (has volume).

Metric System

A system of measurement used by scientists all over the world. 

Mixture

A physical combination of substances that keeps its own properties. Examples: trail mix, sand, and water.

Periods

The horizontal rows of elements on the periodic table. The properties of elements change considerably across a period.

Physical Change

A change where a substance alters its appearance or form without becoming a new substance is called a phase change, such as melting, freezing, or dissolving. 

Physical property

A characteristic of a substance that can be observed or measured without chemically changing the substance. Examples: color, density, and melting point.

Plasma

The fourth state of matter.

Precipitate

A solid substance that is produced during a chemical reaction in a liquid.

Saturated Solution

A solution holding the maximum amount of solute possible at a given temperature. 

Solubility

The maximum amount of solute that can dissolve in a given solvent at a specific temperature. 

Soluble

Describes a substance that can dissolve in a solvent. Example: salt in water.

Solute

The substance that is dissolved in a solution. Example: sugar in sugar water.

Solution

A homogeneous mixture where one substance dissolves in another. Example: sugar in tea.

Solvent

The substance that dissolves in a solution is usually present in larger amounts. Example: water in salt water.

Substance

A particular kind of matter with uniform properties. Examples: steel, oxygen, water.

Suspension

A heterogeneous mixture with large particles that settle out over time. Example: muddy water.

Volume

The amount of space that matter takes up.