Question 1

Which of the following best explains why sodium chloride (NaCl) has properties very different from both sodium metal and chlorine gas?

Accepted Answer

NaCl is a compound with emergent properties that differ from those of sodium and chlorine due to the formation of ionic bonds.

Question 2

Which four elements make up approximately 96% of the human body’s mass?

Accepted Answer

Oxygen, carbon, hydrogen, nitrogen

Question 3

A neutral atom of sodium (Na) has an atomic number of 11 and a mass number of 23. How many neutrons does it have?

Accepted Answer

$$23 - 11 = 12$$

Question 4

Which statement best describes the difference between covalent and ionic bonds?

Accepted Answer

Covalent bonds involve the sharing of electrons, while ionic bonds involve the transfer of electrons.

Question 5

Which of the following best explains why water (H$$_2O) is a $$polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons and partial charges.

Question 6

Which of the following is a trace element required by vertebrates for normal thyroid function?

Accepted Answer

Iodine (I)

Question 7

If an atom has 7 electrons in its outermost shell, what is its likely chemical behavior?

Accepted Answer

It tends to gain one electron to achieve a full valence shell, forming an anion.

Question 8

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 9

Which of the following best explains why geckos can climb smooth walls?

Accepted Answer

Thousands of Van der Waals interactions between the gecko’s toe hairs and the wall surface.

Question 10

Which of the following is true about isotopes of an element?

Accepted Answer

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

Question 11

A radioactive isotope of carbon, $$^{14}C$$, is used in radiometric dating. What makes $$^{14}C $$radioactive?

Accepted Answer

It has an unstable nucleus that decays spontaneously, emitting particles and energy.

Question 12

Which of the following best describes the relationship between electron shells and energy levels?

Accepted Answer

Electrons in outer shells have higher potential energy than those in inner shells.

Question 13

Which of the following is an example of an emergent property?

Accepted Answer

Table salt (NaCl) is edible, while its component elements sodium and chlorine are not.

Question 14

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

Accepted Answer

They have full valence shells, making them stable and unreactive.

Question 15

Which of the following best describes the role of orbitals in determining molecular shape?

Accepted Answer

The arrangement of hybridized orbitals determines the three-dimensional shape of molecules.

Question 16

Which of the following is a real-life application of the concept of valence electrons?

Accepted Answer

The formation of table salt (NaCl) from sodium and chlorine involves the transfer of valence electrons.

Question 17

Which of the following best describes what happens when an electron absorbs energy?

Accepted Answer

It moves to a shell farther from the nucleus.

Question 18

Which of the following best explains why water molecules can form hydrogen bonds with each other?

Accepted Answer

The partial positive charge on hydrogen is attracted to the partial negative charge on oxygen of another molecule.

Question 19

Which of the following best describes the effect of molecular shape on biological function?

Accepted Answer

Molecules with similar shapes can bind to the same biological receptors, producing similar effects.

The Chemical Context of Life: Atoms, Elements, and Chemical Bonds

Study Guide - Practice Questions