Atoms, Elements, Compounds and Molecules

The picture show a/an ...

• element

• atom

• compound

• cycle

The smallest unit of a chemical element

• molecule

• element

• compound

• atom

How many element makes this Hydrogen molecule?

• 1

• 2

• 3

• 0

Answer explanation

There is only 1 element in the molecule which is Hydrogen.

How many atoms are there in the Carbon dioxide compound?

• 1

• 2

• 3

• 4

Answer explanation

There are 3 atoms in Carbon dioxide compound: 1 carbon atom and 2 oxygen atoms.

How many element are there in table sugar?

• 24

• 12

• 3

• 1

Answer explanation

There are 3 elements in water molecule: C = Carbon element, H = Hydrogen element, and O = Oxygen element.

What does the picture show?

• atom
• element
• molecule
• compound

Carbon (C) and hydrogen (H) are pure substances. Each is made of only one type of atom, but carbon atoms are different from hydrogen atoms. Carbon and hydrogen chemically combine to form methane (CH4).

• methane is an element and carbon and hydrogen are compounds.
• carbon, hydrogen, and methane are all elements.
• carbon, hydrogen, and methane are all compounds.
• carbon and hydrogen are elements and methane is a compound.

When two or more atoms link up

• matter

• element

• atom

• molecule

Which one is a COMPOUND?

• H₂ (Hydrogen)

• CO₂ (Carbon dioxide)

• O₂ (Oxygen)

• Cu (Copper)

Answer explanation

A compound is made of different elements bonded together. CO₂ is a compound because it has carbon element and oxygen element.

Pure substance that cannot be separated into simpler substance

• Element

• Atom

• Compound

• Molecule