Exploring Atomic Structure

What is the basic unit of matter?

• cell

• molecule

• compound

• atom

Define a molecule.

• A molecule is a mixture of different substances.

• A molecule is a group of two or more atoms bonded together.

• A molecule is a single atom.

• A molecule is a type of chemical reaction.

How many electrons can the first energy level hold?

• 1

• 8

• 4

• 2

What is the electron configuration of oxygen?

• 1s² 2s² 2p⁴

• 1s² 2s² 2p⁵

• 1s² 2s² 2p²

• 1s² 2s² 2p³

What trend does atomic radius follow across a period?

• The atomic radius decreases across a period.

• The atomic radius remains constant across a period.

• The atomic radius increases across a period.

• The atomic radius fluctuates randomly across a period.

What is the charge of a neutron?

• +1

• 0

• +2

• -1

How do isotopes of an element differ?

• Isotopes differ in the number of protons and electrons.

• Isotopes have the same atomic mass but different chemical properties.

• Isotopes are only distinguished by their color and shape.

• Isotopes differ in the number of neutrons and atomic mass.

What is the atomic mass of an element?

• The atomic mass of an element is the weighted average of the masses of its isotopes.

• The atomic mass is the total number of protons in an atom.

• The atomic mass is the sum of protons and neutrons in a single isotope.

• The atomic mass is the mass of the most abundant isotope only.

What is the law of conservation of mass?

• Mass can be created in chemical reactions.

• Mass is only conserved in physical changes.

• Mass is conserved in chemical reactions; it cannot be created or destroyed.

• Mass can be destroyed during a reaction.

Write the balanced equation for the combustion of methane.

• CH4 + 2 O2 -> CO2 + 2 H2O

• CH4 + O2 -> CO + H2O

• CH4 + 3 O2 -> 2 CO2 + 2 H2O

• C2H6 + O2 -> 2 CO2 + 3 H2O