Foundations of chemistry

Element

A pure substance consisting of only one type of atom.

Molecule

Two or more atoms bonded together, which can be the same or different elements.

Compound

A pure substance composed of two or more different elements chemically bonded.

Mixture

A physical combination of two or more substances where each retains its properties.

Physical Change

A change that does not alter the chemical identity of a substance.

Chemical Change

A change that results in the formation of new substances with new properties.

Evidence of a Chemical Reaction

Signs such as color change, gas formation, precipitate formation, and energy change that indicate a chemical reaction has occurred.

Balancing Chemical Equations

The process of making sure that the same number of each type of atom appears on both sides of a chemical equation.

Scientific Notation

A method to express very large or very small numbers using powers of 10.

Homogeneous Mixtures

Mixtures with uniform composition.

Heterogeneous Mixtures

Mixtures with non-uniform composition.

Filtration

A physical process to separate solids from liquids.

Evaporation

A process of removing a liquid by heating, leaving dissolved solids behind.

Color Change

A sign of a chemical reaction where a new color forms.

Formation of Gas

A sign of a chemical reaction where bubbles appear in the mixture.

Precipitate Formation

The formation of a solid that separates from a liquid.

Energy Change

A sign of a chemical reaction where heat, light, or sound is released or absorbed.

Odor Change

A sign of a chemical reaction where a new smell is noticeable.