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 gold (Au).

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 carbon dioxide (CO2).

Front

How do compounds differ from their constituent elements?

Back

Compounds have different properties than the original elements that make them up. For example, sodium (Na) is a metal and chlorine (Cl) is a gas, but when combined as sodium chloride (NaCl), they form a solid salt.

Front

What is the chemical formula for water?

Back

H2O

Front

Which of the following is an example of a compound: NaCl, O2, or H?

Back

NaCl is a compound; O2 is an element, and H is also an element.

Front

What does the subscript in a chemical formula indicate?

Back

The subscript indicates the number of atoms of the element in the compound. For example, in H2O, the '2' indicates there are two hydrogen atoms.

Front

What is the difference between a mixture and a compound?

Back

A mixture is a combination of two or more substances that are not chemically bonded, while a compound is a substance formed from the chemical bonding of two or more elements.

Front

What is the chemical formula for carbon dioxide?

Back

CO2

Front

Which of the following is NOT a compound: NaCl, CO2, O2?

Back

O2 is not a compound; it is an element.

Front

What is the significance of the periodic table in understanding elements and compounds?

Back

The periodic table organizes all known elements and provides information about their properties, which helps in understanding how they can combine to form compounds.