Introductory Chemistry — Chapter 3: Matter and Energy (Vocabulary Flashcards)

Vocabulary flashcards covering key terms from Chapter 3: Matter and Energy, including definitions of matter, states of matter, mixtures vs. pure substances, energy concepts, and related properties and processes.

Matter

Anything that occupies space and has mass.

Atom

The fundamental building block of matter; the smallest unit of an element that can exist independently in some substances.

Molecule

A chemical combination of two or more atoms bonded together in a definite arrangement.

Element

A pure substance that cannot be broken down into simpler substances; consists of one kind of atom and is listed on the periodic table.

Compound

A pure substance composed of two or more elements in fixed definite proportions; can be decomposed into simpler substances.

Pure substance

Matter with a fixed composition; either an element or a compound.

Mixture

Matter composed of two or more kinds of atoms or molecules in variable proportions.

Homogeneous mixture

A mixture with uniform composition throughout.

Heterogeneous mixture

A mixture with a variable composition and distinct phases.

Solid

State of matter where particles are in fixed locations; definite shape and volume; incompressible.

Liquid

State of matter where particles are close but can flow; definite volume; takes the shape of its container.

Gas

State of matter where particles are far apart and move freely; compressible; takes the shape and volume of its container.

Crystalline solid

A solid in which atoms or molecules occupy specific positions forming a long-range, repeating order.

Amorphous solid

A solid lacking long-range order in its structure.

Ice

Solid water; molecules are closely spaced and vibrate in fixed positions.

Liquid water

Water in the liquid state; molecules are closely spaced and free to move past each other.

Steam

Water in the gaseous state; molecules are separated and move freely with little interaction.

Phase change

A transition between solid, liquid, and gas without a change in chemical composition.

Distillation

A physical separation method based on differences in boiling points; vaporizes components and then condenses them to liquid.

Filtration

A physical separation method where a solid is trapped by filter paper and the liquid passes through.

Law of Conservation of Mass

Matter is neither created nor destroyed in ordinary chemical reactions; mass of reactants equals mass of products.

Energy

The capacity to do work.

Work

The result of a force acting through a distance.

Law of Conservation of Energy

Energy is conserved; it cannot be created or destroyed and can be transformed or transferred.

Kinetic energy

Energy associated with the motion of an object.

Potential energy

Energy associated with the position or composition of a system.

Forms of energy

Different types of energy, including electrical, thermal, and chemical energy.

Temperature

A measure of the thermal energy of matter; higher temperature means more molecular motion.

Heat

The transfer of thermal energy due to a temperature difference.

Temperature scales

Fahrenheit, Celsius, and Kelvin scales used to measure temperature, with characteristic freezing/boiling points for water.

Specific heat capacity

The amount of heat required to raise the temperature of 1 g of a substance by 1°C; units are J/(g·°C).

q = m C ΔT

The equation relating heat (q) to mass (m), specific heat capacity (C), and temperature change (ΔT).

1 cal = 4.184 J

One calorie equals 4.184 joules.

1 Cal (nutritional Calorie) = 1000 cal

A Calorie equals 1000 calories used on food labels.

Exothermic

A chemical reaction that releases energy to its surroundings.

Endothermic

A chemical reaction that absorbs energy from its surroundings.

Reactants

Substances present before a chemical change or reaction.

Products

Substances formed after a chemical change or reaction.

Absolute zero

0 K; the lowest possible temperature where molecular motion virtually stops.

Physical property

A property observed without changing the substance’s composition (e.g., odor, boiling point, density).

Chemical property

A property observed only by changing the substance’s composition (e.g., rusting, flammability, acidity).

Physical change

A change in appearance or state without changing the substance’s composition.

Chemical change

A change that alters the substance’s chemical composition (chemical reaction).