Atoms and Elements

Which of the following is the smallest unit of matter?

• Molecule

• Atom

• Compound

• Mixture

Which of the following statements about elements is true?

• Elements are made of only one type of atom.

• Elements are always found in a liquid state.

• Elements contain two or more different atoms chemically bonded together.

• Elements can only be found in nature.

A compound is different from a mixture because:

• A) A compound can be separated by physical means, but a mixture cannot.

• B) A compound consists of two or more elements chemically bonded together.

• C) A compound contains only one type of atom.

• D) A compound always exists in solid form.

Which of the following is an example of a pure substance?

• Air

• Seawater

• Oxygen gas (O₂)

• Saltwater

Which of the following is a monatomic element?

• Oxygen (O₂)

• Nitrogen (N₂)

• Helium (He)

• Water (H₂O)

A diatomic molecule contains:

• One atom

• Two atoms of the same or different elements

• Three atoms of the same element

• A lattice structure

Which of the following is a triatomic molecule?

• Nitrogen (N₂)

• Carbon dioxide (CO₂)

• Iron (Fe)

• Sodium chloride (NaCl)

Which of the following statements about lattices is true?

• Lattices are made up of atoms arranged in a repeating pattern.

• All lattices are made of metal atoms only.

• Lattices can only form in gases.

• Lattices are the same as molecules.

Which of the following correctly describes a chemical bond?

• A) A force that holds atoms together in compounds and molecules.

• B) A physical force that separates elements from a compound.

• C) A force that exists only in mixtures.

• D) A type of attraction that only exists in metals.

Which of the following is an example of a mixture?

• Water (H₂O)

• Carbon dioxide (CO₂)

• Air

• Sodium chloride (NaCl)