Chemical/Physical Changes and Properties

Physical Properties

Measurable or observable characteristics of a substance that do not change its identity or composition.

Chemical Properties

Characteristics that indicate how a substance reacts with other substances, observed during a chemical change.

Law of Conservation of Mass

Principle stating that matter cannot be created or destroyed in any chemical or physical change.

Chemistry

The scientific study of matter and the changes it undergoes.

Matter

Anything that has mass and volume; encompasses all physical substances.

Mass

The amount of matter in an object, often referred to as "how much stuff."

Energy

The capacity to do work or produce heat.

Weight

The force exerted by gravity on an object's mass.

Pure Substances

Materials with a uniform and definite composition, including elements and compounds.

Elements

Pure substances represented by symbols on the Periodic Table, such as H and He.

Compounds

Substances formed when two or more elements chemically combine, e.g., H2O and CO2.

Mixtures

Combinations of two or more pure substances that are physically mixed together.

Heterogeneous Mixtures

Mixtures with a non-uniform composition where individual parts can be seen and separated.

Examples of Heterogeneous Mixtures

Cereal, pizza, salad.

Colloids

A type of heterogeneous mixture where small particles are dispersed throughout a medium.

Emulsions

A subclass of colloids, typically involving mixtures of liquids that do not mix.

Suspensions

Heterogeneous mixtures where particles are suspended in a liquid or gas.

Homogeneous Mixtures

Mixtures with a uniform composition where individual components cannot be easily separated.

Examples of Homogeneous Mixtures

Sugar water

Solutions

Homogeneous mixtures consisting of a solute dissolved in a solvent.

Solute

The substance that dissolves in a solvent (e.g., sugar in sugar water).

Solvent

The substance that does the dissolving (e.g., water in sugar water).

Endothermic Reaction

A chemical reaction that absorbs heat from its surroundings.

Exothermic Reaction

A chemical reaction that releases heat to its surroundings.

Solid

A state of matter with a definite shape and volume, high density, and is not compressible.

Liquid

A state of matter with an indefinite shape, definite volume, lower density than solids, and is not compressible.

Gas

A state of matter with an indefinite shape and volume, low density, and is compressible.