Elements and Compounds

Front

What is an element?

Back

An element is a pure substance that cannot be broken down into simpler substances by chemical means. Examples include hydrogen (H), oxygen (O), and carbon (C).

Front

What is a compound?

Back

A compound is a substance formed when two or more elements are chemically bonded together. Examples include water (H2O) and sodium chloride (NaCl).

Front

Which of the following represents an element: H2O, NaCl, H2, CaCO3?

Back

H2 is an element.

Front

How many elements are in the compound Na2CO3?

Back

There are 3 elements: sodium (Na), carbon (C), and oxygen (O).

Front

Which of the following is not a compound: HCl, NaCl, Cl, CO2?

Back

Cl is not a compound; it is an element.

Front

What is the smallest unit of an element?

Back

The smallest unit of an element is an atom.

Front

What is the smallest unit of a compound?

Back

The smallest unit of a compound is a molecule.

Front

What is a mixture?

Back

A mixture is a combination of two or more substances that are not chemically bonded. Examples include air and salad.

Front

What is the difference between an element and a compound?

Back

An element is a single type of atom, while a compound consists of two or more different types of atoms chemically bonded together.

Front

What does the chemical formula H2O represent?

Back

H2O represents the compound water, which consists of two hydrogen atoms and one oxygen atom.