Question 1

Which of the following best describes an emergent property, as illustrated by the combination of sodium and chlorine to form sodium chloride?

Accepted Answer

A property that arises only when two or more elements combine, and is not present in the individual elements.

Question 2

Which subatomic particle determines the atomic number of an element?

Accepted Answer

Proton

Question 3

If an atom has 7 protons, 8 neutrons, and 7 electrons, what is its atomic mass in Daltons (Da)?

Accepted Answer

$$15 \ 	ext{Da}$$

Question 4

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 5

What is the maximum number of electrons that can be held in the second electron shell of an atom?

Accepted Answer

$$8$$

Question 6

Which type of chemical bond involves the equal sharing of electrons between atoms?

Accepted Answer

Non-polar covalent bond

Question 7

What is the main reason that oxygen forms polar covalent bonds with hydrogen in water ($$\mathrm{H_2O}$$)?

Accepted Answer

Oxygen is more electronegative than hydrogen, so it pulls shared electrons closer.

Question 8

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions.

Question 9

Which of the following is a trace element essential for human health, as shown in the study materials?

Accepted Answer

Iron

Question 10

A hydrogen bond is best described as:

Accepted Answer

A weak attraction between a partially positive hydrogen atom and a partially negative atom of another molecule.

Question 11

Which of the following equations is balanced?

Accepted Answer

$$\mathrm{2H_2 + O_2$ \rightarrow 2H_2O}$$

Question 12

Which of the following statements about van der Waals forces is correct?

Accepted Answer

They are weak, temporary attractions due to random electron distribution.

Question 13

If a neutral atom of sodium ($$\mathrm{Na}) $$loses one electron, what is the resulting charge and what is the term for this ion?

Accepted Answer

Positive; cation

Question 14

Which of the following best explains why noble gases are chemically inert?

Accepted Answer

They have full valence shells and do not tend to gain or lose electrons.

Question 15

A radioactive isotope of carbon ($$^{14}\mathrm{C}) $$decays by converting a neutron into a proton and an electron. What is the new element formed?

Accepted Answer

Nitrogen

Question 16

Which of the following is true about the mass of electrons compared to protons and neutrons?

Accepted Answer

Electrons are about 1/2000 the mass of a proton or neutron.

Question 17

Which of the following best describes chemical equilibrium in a reaction?

Accepted Answer

The rate of the forward reaction equals the rate of the reverse reaction.

Question 18

Which of the following elements is the most electronegative according to the study materials?

Accepted Answer

Oxygen

Question 19

A molecule of methane ($$\mathrm{CH_4$}) is $$held together by which type of bonds?

Accepted Answer

Non-polar covalent bonds

Question 20

Which of the following best explains why water ($$\mathrm{H_2O}) $$molecules can form hydrogen bonds with each other?

Accepted Answer

Water molecules have partial positive and negative charges due to polar covalent bonds.

Atoms, Elements, and Chemical Bonds: Foundations of Biological Chemistry

Study Guide - Practice Questions