Review: Matter

Which of the following is NOT classified as matter?

• Air

• Electricity

• Diamond

• All the other choices are classified as Matter

Answer explanation

Electricity is a form of energy, not matter. It does not conform with the definition of matter which is anything that occupies space and has mass.

CHOOSE ALL THAT APPLY: Which among the diagrams show the particles of a pure substance?

• 1

• 2

• 3

• 4

Answer explanation

Elements and compounds are classified as pure substances.

[1] and [3] are compounds. [2] is an element.

NOTE: Molecules which are composed of a single type of atom are still classified as elements. Remember that a substance can only be classified as a compound if atoms of different elements are bonded together chemically.

[4] is a mixture because three different substances (one element and two compounds) are interacting or mixing physically.

Which of the following is TRUE about homogeneous mixtures?

• The components of a homogeneous mixture can be separated by filtration.

• Blood, milk and bronze are examples of homogeneous mixtures.

• All liquids can form homogenous mixtures with each other.

• The components of a homogeneous mixture do not settle overtime.

Which set of labels correctly describes the mixtures on the right?

X - Y - Z

• solution-colloid-suspension

• solution-suspension-colloid

• suspension-colloid-solution

• colloid-suspension-solution

Answer explanation

This picture illustrates how the Tyndall effect can help differentiate between solutions, suspensions and colloids.

When a beam of light is passed through a solution, the path of light is not shown in the solution.

Meanwhile, even though a colloid usually seems to have uniform appearance (looks solution-like), the path of the beam of light through the colloid will be seen, unlike in solutions.

Lastly, suspensions can be differentiated from colloids by the evidently larger particle size of at least one of the components of the mixture. Suspensions also usually settle overtime.

CHOOSE ALL THAT APPLY: Covalent bonding will most likely exist between which of the following pairs?

• metal + metal

• non-metal + non-metal

• metal + non-metal

• metal + metalloid

CHOOSE ALL THAT APPLY: Which of the following is TRUE about neutral chlorine-37?

• It has 17 protons

• It has 20 electrons

• It has 37 neutrons

• It has 37 protons and electrons

Answer explanation

In the convention shown, 37 is the mass number while 17 is the atomic number.

Atomic number is equal to the number of protons. If the atom is neutral, this also corresponds to the number of electrons.

The Mass Number is equal to the number of protons plus the number of neutrons. So in the case of Cl-37, the number of neutrons is 20.

CHOOSE ALL THAT APPLY: The diagram shown represents the structure of a certain atom. Which particles in the atom have approximately the same mass?

• e

• p

• n

• none of them.

Answer explanation

The proton and neutron approximately have the same mass, while the electron is much much lighter.

A neutral atom X contains 16 protons. Which statement about atom X is correct?

• It has a mass number of 16

• It contains 6 neutrons

• It contains 16 electrons

• It contains 16 nucleons

Answer explanation

Nucleons are the collective name for particles found in the nucleus (protons and neutrons).

Since the atom is neutral, the number of protons is equal to the number of electrons.

Which of the following is a molecule but NOT a compound?

• Carbon monoxide, CO

• Water, H₂O

• Helium gas, He

• Phosphorus, P₄

Answer explanation

Phosphorus, P_4, is an element because all the atoms bonded in this molecule are the same type.

Oxygen gas exists naturally as a diatomic molecule while argon exists naturally as a monatomic element.

CHOOSE ALL THAT APPLY: If an atom of oxygen is represented by "●" and an atom of argon is represented by "○", which diagram shows a mixture of the two gases?

• 1

• 2

• 3

• 4

Answer explanation

Diatomic molecule means the molecule is composed of two atoms bonded together. Diatomic molecules can be either elements or compounds depending on the nature of the atoms present.

Monoatomic element means the element exists only as one atom and each individual atom is not chemically bonded to anything.