Physical vs. Chemical Changes and Properties in Matter

What is the main difference between physical and chemical changes?

In physical changes, the same substance remains after the change, while in chemical changes, a new substance is formed.

What are some examples of physical changes?

Pounding, pulling, tearing, phase changes (like melting/boiling), dissolving, chopping wood, and breaking glass.

What indicates a chemical change has occurred?

The formation of a new substance with different characteristics, often indicated by a precipitate, gas, color change, or energy change.

What is a precipitate?

A solid substance that settles or falls out of a solution, often indicating a chemical change.

What are physical properties?

Descriptive properties like length, color, or temperature that do not involve a change in the substance.

What are intensive physical properties?

Properties that do not depend on the amount of matter present, such as density, ductility, and melting point.

What are extensive physical properties?

Properties that depend on the amount of matter present, such as length, height, mass, and volume.

What are chemical properties?

Properties that describe matter undergoing a chemical change or its ability to resist a chemical change.

Give examples of chemical properties.

Reacts with air, resists corrosion, gives off gas when exposed to acid, rusts, and decomposes in soil.

What is matter?

Matter occupies space and possesses mass; it may exist as a solid, liquid, or gas.

What is a mixture?

Matter consisting of two or more pure substances that retain their individual identities and can be separated by physical methods.

What is a homogeneous mixture?

A mixture having a uniform composition and properties throughout, also called a solution.

What is a heterogeneous mixture?

A mixture not uniform in composition and properties throughout.

What are physical methods of separation?

Methods such as filtration, distillation, and crystallization used to separate mixtures.

What is a pure substance?

Matter having an invariant chemical composition and distinct properties.

What is an element?

A fundamental substance that cannot be separated into simpler substances by chemical methods.

What is a compound?

A substance composed of two or more elements in fixed proportions, separable into simpler substances only by chemical methods.

What are chemical methods of separation?

Methods such as electrolysis used to separate compounds into their constituent elements.