Chapter 1-8 Chemistry Review: Substances, Mixtures, States, and Energy

Vocabulary flashcards covering key terms and concepts from the notes on substances, mixtures, states of matter, physical/chemical changes, and energy.

Pure substance

A substance composed of only one type of particle; includes elements and compounds.

Element

A pure substance consisting of only one kind of atom; building blocks of matter; up to 118 known elements.

Compound

A pure substance made of two or more elements chemically bonded in fixed proportions (e.g., CO2).

Molecule

The smallest unit of a substance that retains its chemical properties (e.g., CO2 is a molecule).

CO2 (carbon dioxide)

A molecule with one carbon atom bonded to two oxygen atoms; example of a compound.

Mixture

A type of matter that contains two or more substances physically mixed, not chemically combined.

Homogeneous mixture

A mixture with uniform composition throughout; components are not visually distinguishable (e.g., sugar in water).

Heterogeneous mixture

A mixture with nonuniform composition; components are visibly different (e.g., sand in water).

Physical property

A property observed or measured without changing the substance's identity (e.g., color, density, boiling point).

Chemical property

A property observed when a substance undergoes a chemical change (e.g., flammability, reactivity with oxygen).

Physical change

A change that does not form new substances; changes in shape, size, or phase.

Chemical change

A change that forms new substances; old molecules are transformed (e.g., burning, rusting).

Solid

State of matter with definite shape and volume; particles are tightly packed with strong interactions.

Liquid

State with definite volume but no fixed shape; takes the shape of its container.

Gas

State with no definite shape or volume; particles are far apart and move freely.

Kinetic energy

Energy of motion; depends on mass and velocity (KE = 1/2 mv^2).

Potential energy

Energy stored due to position; EP = mgh; can be converted to kinetic energy.

Joule

SI unit of energy; 1 J = 1 kg·m^2/s^2.

Kilojoule (kJ)

Energy unit equal to 1000 J; common in chemistry.

Calorie (cal)

Small unit of energy; 1 cal = 4.184 J.

Kilocalorie (kcal)

Food energy unit; 1 kcal = 1000 cal = 4184 J; often written as Cal (capital C) in nutrition.

Kelvin

Absolute temperature scale; 0 K is absolute zero (theoretical).

Celsius

Temperature scale with 0°C as the freezing point and 100°C as the boiling point of water at 1 atm.

Fahrenheit

Temperature scale used mainly in the US; 32°F is freezing, 212°F is boiling at 1 atm.

Absolute zero

Lowest possible temperature; 0 K (−273.15°C) where particles have minimal motion.

EP = m g h

Potential energy formula; E_p = m × g × h (mass × gravity × height).

Bond energy

Energy stored in a chemical bond; energy required to break bonds; a form of potential energy.

Chemical energy

Energy stored in chemical bonds; released during chemical reactions (e.g., oxidation of food).