Introductory Chemistry – Chapter 3: Matter and Energy

Vocabulary flashcards summarizing the key terms and definitions from Chapter 3: Matter and Energy, covering states of matter, classification of matter, physical and chemical properties and changes, conservation laws, energy units, temperature scales, and separation techniques.

Matter

Anything that occupies space and has mass.

Atom

The fundamental submicroscopic particle that is the basic building block of matter.

Molecule

Two or more atoms chemically bonded in a specific geometric arrangement.

Solid

State of matter with closely packed particles that vibrate about fixed positions; definite shape and volume; incompressible.

Liquid

State of matter with closely spaced particles that can move past one another; definite volume, indefinite shape; incompressible.

Gas

State of matter with widely separated particles in rapid motion; indefinite shape and volume; compressible.

Pure Substance

Matter composed of only one type of atom or molecule.

Element

A pure substance that cannot be broken down into simpler substances by chemical means.

Compound

A pure substance composed of two or more elements chemically combined in fixed, definite proportions.

Mixture

Physical combination of two or more substances in variable proportions.

Homogeneous Mixture

A mixture with uniform composition throughout (e.g., air, salt water).

Heterogeneous Mixture

A mixture with non-uniform composition (e.g., sand in water).

Physical Property

Characteristic displayed by a substance without changing its composition (e.g., odor, color, density).

Chemical Property

Characteristic that appears only when a substance undergoes a chemical change (e.g., flammability).

Physical Change

A change that alters appearance or state but not composition, such as melting or distillation.

Chemical Change

A process in which matter undergoes a chemical reaction and forms new substances.

Reactant

Starting substance in a chemical reaction.

Product

Substance formed as a result of a chemical reaction.

Conservation of Mass

Principle stating that matter is neither created nor destroyed in a chemical reaction.

Energy

The capacity to do work; conserved according to the law of conservation of energy.

Joule (J)

SI unit of energy.

Calorie (cal)

Energy required to raise the temperature of 1 g of water by 1 °C; 4.184 J.

Calorie (Cal)

Nutritional unit equal to 1000 cal or one kilocalorie.

Kilowatt-hour (kWh)

Energy unit commonly used for electricity; 1 kWh = 3.60 × 10⁶ J.

Exothermic Reaction

Chemical reaction that releases energy to surroundings.

Endothermic Reaction

Chemical reaction that absorbs energy from surroundings.

Heat

Transfer of thermal energy due to temperature difference.

Temperature

Measure of the thermal energy content of a substance.

Fahrenheit Scale

Temperature scale on which water freezes at 32 °F and boils at 212 °F.

Celsius Scale

Temperature scale on which water freezes at 0 °C and boils at 100 °C.

Kelvin Scale

Absolute temperature scale starting at 0 K (absolute zero); no negative values.

Absolute Zero

Lowest possible temperature (0 K) where molecular motion virtually stops.

Heat Capacity

Quantity of heat needed to change the temperature of a given amount of substance by 1 °C.

Specific Heat Capacity

Heat capacity per gram of substance, expressed in J g⁻¹ °C⁻¹.

q = m C ΔT

Equation relating heat (q), mass (m), specific heat (C), and temperature change (ΔT).

ΔH_fus

Heat of fusion; energy required to melt one mole of a substance at its melting point.

Distillation

Separation technique that uses differences in volatility to separate components of a liquid mixture.

Filtration

Separation method that removes a solid from a liquid by passing the mixture through filter paper.

Compressibility

Measure of how much the volume of matter decreases under pressure; significant only for gases.