Elements compounds mixtures key terms

What is an element?

An element is a pure substance made of only one type of atom. Examples include hydrogen (H) and oxygen (O).

What is a compound?

A compound is a substance formed when two or more elements chemically bond. Water (H2O) is a common example.

What is a mixture?

A mixture is made of two or more substances mixed together but not chemically combined. Examples are saltwater and air.

True or false: Elements can be broken down into simpler substances.

False, because elements are the simplest form of matter.

Difference between elements and compounds

Elements consist of one type of atom, while compounds consist of two or more types of atoms.

Fill in the blank: A ___ is a combination of different substances.

mixture

Question: Which of these is a compound?

Water (H2O) is a compound.

True or false: Mixtures have a fixed composition.

False, because mixtures can have varying amounts of each substance.

What is a homogeneous mixture?

A homogeneous mixture has a uniform composition. An example is vinegar.

What is a heterogeneous mixture?

A heterogeneous mixture has visibly different substances. An example is salad.

Question: What is the main difference between a compound and a mixture?

A compound is chemically bonded; a mixture is not.

Fill in the blank: Salt is a ___ made from sodium and chlorine.

compound

Question: Can elements exist as mixtures?

Yes, elements can be mixed but remain distinct, like iron filings and sand.

What is the formula for water?

The formula for water is H2O.

True or false: Mixtures can be separated by physical means.

True, because components of mixtures can be separated without chemical reactions.

Question: Which of these is NOT an element?

Salt (NaCl) is not an element; it is a compound.