Chemistry Unit 1

Matter

Anything that takes up space and has mass.

States of Matter

The distinct forms that different phases of matter take on, including solid, liquid, and gas.

Solid

A state of matter with a fixed volume and fixed shape; particles are fixed but can vibrate.

Liquid

A state of matter with a fixed volume but unfixed shape; particles are close together and can flow past each other.

Gas

A state of matter with unfixed volume and unfixed shape; gas particles are far apart and can flow past each other.

Physical Properties

Characteristics of a substance that can be determined without changing its identity or composition (e.g., color, shape, size, texture, smell, mass, density, melting point, boiling point).

Chemical Properties

Characteristics that become evident after a chemical reaction, resulting in a new product with different properties (e.g., flammability, reactivity, toxicity).

Element

The simplest form of matter that has a unique set of properties and cannot be broken down further.

Compound

A substance that contains two or more elements chemically combined in a fixed proportion.

Chemical Symbols

Notations that represent elements, typically consisting of one or two letters (e.g., H for hydrogen, O for oxygen).

Chemical Formulas

Notations that represent compounds, indicating the elements and their proportions (e.g., H2O for water, CO for carbon monoxide).

Mixtures

Combinations of two or more substances that can be separated by physical means.

Pure Substances

Materials that have a uniform and definite composition, which can be either elements or compounds.

Homogeneous Mixture

A mixture that has a uniform composition throughout.

Heterogeneous Mixture

A mixture that does not have a uniform composition and can be separated into distinct components.

Physical Change

A change that alters one or more physical properties of a substance without changing its composition (e.g., melting, freezing, cutting).

Chemical Change

A change that occurs when a substance combines or reacts with another substance to form a new product (e.g., rusting, rotting).

Indicators of Chemical Change

Signs that a chemical change has occurred, such as a change in color, production of gas, transfer of energy, or formation of a precipitate.

Precipitate

A solid that forms and settles out of a liquid mixture during a chemical reaction.