Chem 1: Matter, Properties & Scientific Method (Chapter 1)

34 question-and-answer flashcards covering definitions, classifications, properties of matter, phase changes, mixture separation, conservation of mass, and the scientific method.

What is the scientific definition of matter?

Anything that has both mass and volume.

How do physical properties differ from chemical properties?

Physical properties can be observed without changing the substance’s chemical identity, whereas chemical properties can only be observed through a change in chemical identity.

What is an intensive property?

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

What is an extensive property?

A property that depends on the amount of substance present (e.g., mass, heat).

Classify temperature and heat as intensive or extensive.

Temperature is intensive; heat is extensive.

List the three common physical states of matter and describe their shape and volume.

Solid: fixed shape and fixed volume; Liquid: indefinite shape, fixed volume; Gas: indefinite shape and indefinite volume.

Why are gases compressible while solids are not?

Gas particles are far apart and can be pushed closer together; solid particles are closely packed in a fixed arrangement, leaving little space to compress.

What is a crystalline solid? Give two examples.

A solid with particles arranged in an orderly geometric pattern; examples: salt (NaCl) and diamond.

What is an amorphous solid? Give two examples.

A solid whose particles lack a long-range geometric order; examples: plastic and glass.

Give three examples of physical changes.

Melting ice, boiling water, dissolving sugar in water.

Give three examples of chemical changes.

Rusting iron, burning wood, souring milk.

Match each phase change with its direction of state change: melting, freezing, sublimation, deposition, boiling, condensation.

Melting: solid→liquid; Freezing: liquid→solid; Sublimation: solid→gas; Deposition: gas→solid; Boiling (vaporization): liquid→gas; Condensation: gas→liquid.

Define a pure substance.

Matter with a constant composition in which all samples have the same pieces in the same percentages.

Define a mixture.

A combination of two or more pure substances that can vary in composition and can be separated by physical methods.

Distinguish between homogeneous and heterogeneous mixtures.

Homogeneous mixtures (solutions) have uniform composition throughout; heterogeneous mixtures contain regions of different composition.

Which separation technique exploits differences in boiling point?

Distillation.

Which separation technique exploits state of matter differences to separate solids from liquids?

Filtration.

State the Law of Conservation of Mass.

Matter is neither created nor destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.

Who is credited with formulating the Law of Conservation of Mass?

Antoine Lavoisier.

If 58 g of butane burns with 208 g of oxygen, what total mass of products forms?

266 g of products (carbon dioxide + water).

What is an element?

A pure substance that cannot be decomposed into simpler substances by chemical changes and is made of identical atoms.

What is a compound?

A pure substance that contains more than one element and can be decomposed into those elements by chemical change.

Define molecule.

The smallest unit of a substance that retains the chemical properties of that substance; composed of two or more chemically bonded atoms.

Approximately how many elements occur naturally?

About 91 elements occur naturally.

List the basic steps of the scientific method in order.

Observation/Problem, Hypothesis, Experiment, Results/Conclusions, leading to Theory or Law.

After formulating a hypothesis, what is the next step in the scientific method?

Perform experiments to test the hypothesis.

Differentiate between a scientific law and a scientific theory.

A law summarizes a set of related observations (what happens), whereas a theory provides the underlying explanation (why it happens).

Give two examples of common chemical properties.

Flammability and acidity (or reactivity, corrosiveness, etc.).

Give two examples of common physical properties.

Density and melting point (or color, hardness, etc.).

What physical property is defined as mass per unit volume?

Density.

What is volatility?

The tendency of a substance to vaporize; a physical property related to boiling point.

Dissolving table salt in water—is this a physical or chemical change?

Physical change (no new substances are formed).

Define inertness as a chemical property.

The tendency of a substance to resist chemical reaction; very low reactivity.

Which states of matter have a fixed volume?

Solids and liquids.

In introductory chemistry, what common term is used for a homogeneous mixture?

Solution.