- Matter is anything that has mass and occupies space.
- All matter is made up of small particles called atoms.
- Matter can exist as a solid, a liquid, or a gas.
Particle Theory of Matter
- Matter is made up of tiny particles (atoms & molecules) that are in constant motion and held together by strong electric forces.
- Temperature affects the speed of the particles. The higher the temperature, the faster the speed of the particles.
- There are large empty spaces between the particles.
- Each substance has unique particles that are different from the particles of other substances.
Matter: Elements, Compounds, Mixtures
- Matter can be classified as elements (oxygen, gold, sodium), compounds (water - H2O, carbon
dioxide - CO2), and mixtures (air, salad dressing).
- The atoms of any element are alike but are different from atoms of other elements.
- Compounds consist of two or more elements that are chemically combined in a fixed ratio.
- Mixtures also consist of two or more substances, but the substances are not chemically combined.
Compounds: Acids vs. Bases; Inorganic vs. Organic
Compounds can be classified in several ways including:
- acids, bases, salts.
- inorganic and organic compounds (organic compounds contain carbon).
Acids and Bases
- Acids make up an important group of compounds that contain hydrogen. When acids dissolve in water, hydrogen ion (H+) is released into the resulting solution.
- A base is a substance that releases hydroxide ions (OH-) into solution.
- pH is a measure of the hydrogen ion concentration in a solution.
The pH Scale
- The pH scale ranges from 0-14.
- Solutions with a pH lower than 7 are acidic.
- Solutions with a pH greater than 7 are basic.
- A pH of 7 is neutral.
- When an acid reacts with a base, a salt is formed along with water.
Physical Properties of Matter
- Matter can be described by its physical properties that include
- melting point
- boiling point
- Some physical properties, such as density, boiling point, and solubility, are characteristic of a specific substance and do not depend on the size of the sample.
- Equal volumes of different substances usually have different masses (due to different densities).
- Matter can also be described by its chemical properties that include:
- A chemical property indicates whether a substance can undergo a chemical change.