General Chemistry I – Matter, Properties, Pure Substances, and Mixtures (Lessons 1.1 & 1.2)

A set of question-and-answer flashcards covering the definitions, properties, phase changes, classifications, and examples related to matter, its states, physical versus chemical properties, and distinctions between pure substances and mixtures.

What is the scientific definition of matter?

Matter is any substance composed of particles that has mass, occupies space (volume), and exhibits inertia.

Which syringe is easier to compress—one filled with air or one containing a small piece of wood—and why?

The syringe filled with air; gases are far more compressible than solids.

Name the four fundamental states of matter discussed in the lesson.

Solid, liquid, gas, and plasma.

How do the shape and volume of a solid compare with those of a liquid and a gas?

A solid has definite shape and volume; a liquid has definite volume but no definite shape; a gas has neither definite shape nor definite volume.

Why is plasma an excellent conductor of electricity?

Because it is an ionized gas whose charged particles respond readily to electric and magnetic fields.

Give an everyday example of plasma.

Lightning (other examples include stars and neon signs).

Describe the particle arrangement in a solid.

Particles are packed tightly in a rigid, fixed lattice and vibrate about fixed positions.

Describe the particle motion in a liquid.

Particles are close together but can slide past one another, allowing the liquid to flow.

Describe the particle motion in a gas.

Particles are far apart, move randomly at high speed, and collide elastically with little or no attraction between them.

Which state of matter is highly compressible?

Gas.

What primary factor determines the state of matter of a substance?

The energy (particularly kinetic energy) of its particles.

List the six common phase changes between solid, liquid, and gas.

Melting, freezing, vaporization (boiling/evaporation), condensation, sublimation, and deposition.

What phase change converts a gas into plasma?

Ionization.

What is the reverse process of ionization (plasma becoming gas)?

Recombination (or de-ionization).

Define an extensive property and give two examples.

A property that depends on the amount of matter present; examples: mass, volume, length, weight.

Define an intensive property and give two examples.

A property that does not depend on the amount of matter; examples: density, boiling point, color, solubility.

Is density an intensive or an extensive property?

Intensive.

Is mass an intensive or an extensive property?

Extensive.

Which physical property expresses the amount of mass in a given volume?

Density.

List three common methods to increase the solubility of a solid in a solvent.

Heating the solvent, smashing/grinding the solute, and mixing/stirring the solution.

What is a chemical property?

A characteristic observable only when a substance undergoes a chemical change to form a new substance.

Give two examples of chemical properties.

Flammability and reactivity (such as combustibility or tendency to oxidize).

In the water example, why is "causing iron to rust" classified as a chemical property?

Because it describes water’s ability to chemically react with iron to form a new compound (iron oxide).

Into what two categories are physical properties divided based on dependence on amount of matter?

Intensive properties and extensive properties.

What are the two broad chemical categories used to classify all matter?

Pure substances and mixtures.

Define a pure substance.

Matter with a definite, uniform composition that cannot be separated by physical means; includes elements and compounds.

Distinguish between an element and a compound.

An element consists of one type of atom; a compound consists of atoms of two or more elements chemically bonded in fixed ratios.

Are all molecules compounds? Explain.

No. All compounds are molecules, but molecules like O₂ or N₂ contain only one element and are therefore not compounds.

List the seven diatomic elements.

Hydrogen (H₂), Nitrogen (N₂), Fluorine (F₂), Oxygen (O₂), Iodine (I₂), Chlorine (Cl₂), and Bromine (Br₂).

Define a mixture.

A combination of two or more substances that are not chemically bonded and retain their individual properties.

Contrast homogeneous and heterogeneous mixtures.

Homogeneous mixtures are uniform throughout; heterogeneous mixtures have visibly different parts or phases.

Give two examples of homogeneous mixtures.

Air and rubbing alcohol (other examples: wine, carbonated soft drinks).

Give two examples of heterogeneous mixtures.

Water and oil mixture, and salt-and-pepper blend (other examples: mixed nuts, pizza).

What type of mixture is a solution, and what are its components called?

A solution is a homogeneous mixture consisting of a solute dissolved in a solvent.

Define a suspension.

A heterogeneous mixture in which large particles are dispersed in a liquid or gas and will eventually settle out.

Define a colloid.

A mixture with intermediate-size particles that remain dispersed, scatter light, and do not settle out (appearing cloudy).

What label on a bottle suggests the contents are a suspension?

“Shake well before use.”

Classify distilled water: pure substance or mixture?

Pure substance (the compound H₂O).

How is brown sugar classified and why?

Mixture, because it contains sucrose crystals mixed with molasses, giving it variable composition.

Why is classifying matter solely by phase (solid, liquid, gas) inadequate for chemists?

Because a single substance can exist in multiple phases, and phase alone does not reveal composition or bonding characteristics.