Chapter: Matter, Pure Substances, and Atomic Theory (Lecture Notes Review)

flashcards covering basic definitions and classifications from the notes: matter, pure substances, mixtures, elements, compounds, homogeneous/heterogeneous mixtures, physical vs chemical properties/changes, states of matter, atoms and molecules, and the scientific theory behind these concepts.

What defines a pure substance?

Matter with a fixed composition, made of a single type of particle (atom or molecule), and all samples have the same intensive properties.

What is a mixture?

Matter with variable composition; made of two or more types of particles; samples may show different intensive properties.

What is an element?

A pure substance made of only one type of atom.

What is a compound?

A pure substance made of two or more different types of atoms chemically bonded; can be decomposed into simpler substances.

What is a homogeneous mixture?

A mixture with uniform composition and properties throughout; appears as one substance.

What is a heterogeneous mixture?

A mixture with nonuniform composition; contains two or more different kinds of matter that can be seen.

What are physical properties?

Properties that can be observed or measured without changing the substance's composition (e.g., color, density, odor, melting point).

What are chemical properties?

Properties that describe how a substance may undergo chemical change (e.g., flammability, toxicity).

What is a physical change?

A change in appearance or form that does not change the substance's composition.

What is a chemical change?

A process that changes the composition of matter, forming new substances.

What is a crystalline solid?

A solid with a long-range repeating order of its particles (e.g., salt, diamond, sugar).

What is an amorphous solid?

A solid without long-range order; particles distributed randomly (e.g., plastic, glass, charcoal).

What are solids, liquids, and gases?

Three fundamental states of matter with different particle arrangements and properties: solids are rigid, liquids flow, gases are compressible and fill their container.

What distinguishes a gas?

Particles are far apart, move freely, and gases are compressible; they fill the space available.

What distinguishes a liquid?

Definite volume, takes the shape of its container, and flows.

What distinguishes a solid?

Definite shape and volume; particles in close, repeating order.

How can matter be classified by components?

Matter can be classified as elements, compounds, and mixtures.

Can an element be separated into simpler substances by chemical means?

No; elements cannot be separated into simpler substances by chemical means.

Can a compound be separated into simpler substances?

Yes; compounds can be decomposed into simpler substances by chemical means.

Can a mixture be separated into simpler substances?

Yes; mixtures can be separated into their components by physical methods.

What are atoms and molecules?

Atoms are the building blocks of matter; molecules are groups of two or more atoms bonded together.

What is the scientific theory in this context?

A general explanation for natural phenomena, supported by experiments and observations; models are used to explain and predict.