Question 1

Which of the following statements best explains why sodium (Na) and chlorine (Cl) react to form sodium chloride (NaCl)?

Accepted Answer

Sodium donates an electron to chlorine, resulting in the formation of oppositely charged ions that attract each other.

Question 2

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 3

A carbon atom has 6 protons, 6 neutrons, and 6 electrons. What is its atomic number and mass number?

Accepted Answer

Atomic number = 6, Mass number = 12

Question 4

Which element makes up the largest percentage of the human body by mass?

Accepted Answer

Oxygen

Question 5

What type of bond is formed when two atoms share a pair of electrons?

Accepted Answer

Covalent bond

Question 6

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally, resulting in partial charges on the atoms.

Question 7

If an atom has an atomic number of 7 and a mass number of 15, how many neutrons does it have?

Accepted Answer

$$15 - 7 = 8$$

Question 8

Which of the following is true about hydrogen bonds?

Accepted Answer

They occur when a hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom.

Question 9

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.

Question 10

A radioactive isotope of carbon, carbon-14, is used in radiometric dating. What makes carbon-14 different from the more common carbon-12?

Accepted Answer

Carbon-14 has more neutrons than carbon-12.

Question 11

Which of the following best describes a compound?

Accepted Answer

A substance consisting of two or more elements in a fixed ratio.

Question 12

Which of the following elements is NOT one of the four most abundant elements in the human body?

Accepted Answer

Calcium

Question 13

Which of the following statements about valence electrons is correct?

Accepted Answer

Valence electrons determine the chemical behavior of an atom.

Question 14

Which of the following is a real-world example of an ionic compound?

Accepted Answer

Sodium chloride (NaCl)

Question 15

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

Accepted Answer

They have a full valence shell of electrons.

Question 16

Which of the following best describes the relationship between atomic number and the identity of an element?

Accepted Answer

The atomic number is the number of protons, which determines the element.

Question 17

Which of the following scenarios best illustrates the concept of electronegativity?

Accepted Answer

An oxygen atom in a water molecule pulls shared electrons closer to itself, creating partial charges.

Question 18

Which of the following equations correctly represents the calculation of the mass number of an atom?

Accepted Answer

$$	ext{Mass number} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

Question 19

A molecule of methane (CH$$_4) $$contains how many covalent bonds?

Accepted Answer

4

Question 20

Which of the following best describes the difference between a molecule and a compound?

Accepted Answer

A molecule is a group of atoms held together by covalent bonds, while a compound consists of two or more different elements in a fixed ratio.

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

Study Guide - Practice Questions