CHM1045 Chapter 1

A set of vocabulary flashcards covering core Chapter 1 concepts: matter, phases, properties, substance types, atomic structure, and the periodic table.

Matter

Anything that occupies space and has mass.

Phase of matter

A distinct form of matter with specific properties; common phases are solid, liquid, and gas.

Solid

A phase of matter with definite shape and volume; particles are tightly packed.

Liquid

A phase of matter with definite volume but takes the shape of its container; flows.

Gas

A phase of matter with no definite shape or volume; expands to fill its container.

Macroscopic domain

The observable, everyday-scale view of matter.

Microscopic domain

The atomic/molecular scale where particles and bonds are seen.

Symbolic domain

The use of symbols and formulas (e.g., H2O, (g), (s)) to represent substances.

Element

A substance that cannot be broken down into simpler substances by chemical means; may exist as atoms or as molecules of that element (e.g., O2, S8).

Atom

The smallest unit of an element that retains the element’s properties.

Molecule

Two or more atoms bonded together.

Compound

A substance composed of two or more elements chemically bonded.

Pure substance

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

Observation

Information gathered through the senses or measurements.

Inference

A conclusion drawn from observations; not directly observed.

Physical property

A property that can be measured without changing the substance’s identity (e.g., density, color, melting point, conductivity).

Chemical property

A property describing how a substance may undergo chemical change (e.g., flammability, acidity, reactivity).

Physical change

A change in matter that does not alter its chemical identity (e.g., melting, phase change).

Chemical change

A change in matter that produces new substances with different identities.

Intensive property

A property that does not depend on the amount of matter (e.g., density, temperature, color).

Extensive property

A property that depends on the amount of matter (e.g., mass, volume, length).

Law of Conservation of Matter

In a closed system, mass remains constant during physical and chemical changes.

Mixture

A combination of two or more substances not bonded chemically.

Atomic number

The number of protons in an atom; identifies the element.

Symbol (chemical symbol)

A one- or two-letter code that represents an element (e.g., H, He, Co).

Atomic mass

The mass of an atom, roughly the sum of protons and neutrons.

Periodic table

Organization of elements by increasing atomic number into periods and groups.

Period

A horizontal row in the periodic table.

Group

A vertical column in the periodic table; elements in a group share properties.

Density

Mass per unit volume; an intensive physical property.

Melting point

The temperature at which a solid changes to a liquid.

Boiling point

The temperature at which a liquid changes to a gas.

Homogeneous

Uniform in structure or composition throughout.

Heterogeneous

Diverse in character or content; consisting of dissimilar elements or parts.