Unit 1 and 2 Review

Front

What is a pure substance?

Back

A pure substance is a material that has a constant composition and consistent properties throughout. Examples include elements and compounds.

Front

Which of the following is NOT a pure substance?

Back

Milk is not a pure substance; it is a heterogeneous mixture.

Front

What is a homogeneous mixture?

Back

A homogeneous mixture is a mixture that has a uniform composition throughout. An example is salt water.

Front

What is a heterogeneous mixture?

Back

A heterogeneous mixture is a mixture where the components are not uniform and can be easily distinguished. An example is a salad.

Front

What is a chemical change?

Back

A chemical change is a process that involves the transformation of one or more substances into different substances. An example is burning wood.

Front

What is a physical change?

Back

A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. An example is melting ice.

Front

What are valence electrons?

Back

Valence electrons are the electrons in the outermost shell of an atom that are involved in chemical bonding.

Front

How does the number of valence electrons affect reactivity?

Back

The number of valence electrons determines how an element will react chemically; elements with fewer or more valence electrons tend to be more reactive.

Front

What is the difference between an element and a compound?

Back

An element is a pure substance that cannot be broken down into simpler substances, while a compound is a substance formed when two or more elements chemically bond together.

Front

What is the significance of the atomic mass?

Back

Atomic mass is the weighted average mass of an element's isotopes and is important for understanding the element's properties and behavior.