OL Atoms and Molecules

The chemical formula for water is H₂O. What does the formula show about each element in the compound?

• the number of valence electrons

• the charge of the compound

• the mass of protons in each atom

• the number of atoms of each element

How many atoms of carbon are included in one molecule of the compound Na₂C₂O₄?

• 1

• 2

• 3

• 4

How many atoms of oxygen are in a molecule of glucose, C₆H₁₂O₆?

• 1

• 6

• 12

• 24

Structural differences between different chemicals can be represented in models of the particles. Which drawing BEST represents a compound?

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Which can be broken down chemically into simpler substances?

• isotopes

• atoms

• compounds

• elements

Which chemical cannot be further broken down into other chemicals using ordinary laboratory processes?

• Salt (NaCl)

• Water (H2O)

• Iron (Fe)

• Limestone (CaCO3)

Which of these are broken down during chemical, but not physical, changes?

• elements

• mixtures

• solutions

• compounds

Which of the following is an example of a compound?

• copper

• iron

• carbon

• water

Which substance is composed of only one type of atom?

• water

• gold

• salt

• sugar

Which is a compound?

• Nitrogen (N₂)

• Neon (Ne)

• Ozone (O₃)

• Ammonia (NH₃)