$$\text{Atomic mass} = \text{Number of protons} + \text{Number of neutrons}$$

Question 1

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

Accepted Answer

Atomic number is the number of protons, while atomic mass is the sum of protons and neutrons.

Question 2

A sodium atom ($$\mathrm{Na}) $$loses one electron to form a sodium ion ($$\mathrm{Na}^+). $$What is the resulting charge and why?

Accepted Answer

The sodium ion has a positive charge because it lost an electron.

Question 3

Which of the following is true about isotopes?

Accepted Answer

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

Question 4

Which equation correctly represents the calculation of atomic mass?

Accepted Answer

$$	ext{Atomic mass} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

Question 5

Which of the following elements is most abundant in the human body by mass?

Accepted Answer

Oxygen

Question 6

A molecule of water ($$\mathrm{H}_2\mathrm{O}) is $$formed by which type of chemical bond?

Accepted Answer

Covalent bond between two hydrogen atoms and one oxygen atom

Question 7

Which statement best explains why elements with filled valence shells are chemically inert?

Accepted Answer

Their outermost electron shell is full, so they do not readily react with other atoms.

Question 8

Which of the following is a correct description of a cation?

Accepted Answer

An atom that has lost electrons and has a positive charge.

Question 9

Which of the following best describes a nonpolar covalent bond?

Accepted Answer

Electrons are shared equally between atoms, resulting in no charge difference.

Question 10

If an atom has 6 protons, 6 neutrons, and 6 electrons, what is its atomic number and atomic mass?

Accepted Answer

Atomic number: 6, Atomic mass: 12

Question 11

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

Accepted Answer

Sodium chloride ($$\mathrm{NaCl})$$

Question 12

Which principle element is essential for the formation of ATP and nucleic acids in the human body?

Accepted Answer

Phosphorus

Question 13

Which of the following best explains why sodium and chlorine form an ionic bond?

Accepted Answer

Sodium loses an electron to become a cation, and chlorine gains an electron to become an anion, resulting in electrostatic attraction.

Question 14

Which equation represents the formation of a sodium ion from a sodium atom?

Accepted Answer

$$\mathrm{Na} \rightarrow \mathrm{Na}^+ + e^-$$

Question 15

Which of the following statements about energy levels in atoms is correct?

Accepted Answer

Electrons in the outermost shell have higher energy than those in inner shells.

Question 16

Which of the following is a property of polar covalent bonds?

Accepted Answer

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

Question 17

Which element is most important for cellular respiration and energy production in the human body?

Accepted Answer

Oxygen

Question 18

A molecule of carbon dioxide ($$\mathrm{CO}_2) is $$formed by which type of bond?

Accepted Answer

Double covalent bonds between carbon and each oxygen atom

Question 19

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

Accepted Answer

A compound consists of atoms of two or more different elements, while a molecule can consist of atoms of the same or different elements.

Question 20

Which of the following is true regarding the three states of matter in the human body?

Accepted Answer

Matter in the body can exist as solids, liquids, or gases depending on temperature and pressure.

Chemical Level of Organization: Atoms, Molecules, and Compounds in Anatomy & Physiology

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