$$\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}$$

Question 1

Which of the following best describes an element?

Accepted Answer

A substance that cannot be broken down into simpler substances by chemical reactions.

Question 2

What is the atomic number of an atom?

Accepted Answer

The number of protons in the nucleus.

Question 3

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

Accepted Answer

$$12$$

Question 4

Which subatomic particle is directly involved in chemical reactions between atoms?

Accepted Answer

Electrons

Question 5

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

Accepted Answer

$$12$$

Question 6

Which statement about valence electrons is correct?

Accepted Answer

Valence electrons determine the chemical behavior of an atom.

Question 7

What type of chemical bond involves the sharing of electron pairs between atoms?

Accepted Answer

Covalent bond

Question 8

Which of the following best explains why water molecules are polar?

Accepted Answer

The electrons are distributed unevenly, creating regions of partial positive and negative charge.

Question 9

A hydrogen bond is formed when:

Accepted Answer

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

Question 10

Which of the following is true about ionic bonds?

Accepted Answer

They form when one atom donates electrons to another, resulting in oppositely charged ions that attract each other.

Question 11

If an atom has a full valence shell, what is its chemical reactivity?

Accepted Answer

It does not readily interact with other atoms.

Question 12

Which of the following is a cation?

Accepted Answer

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

Question 13

Which of the following best describes a compound?

Accepted Answer

A substance composed of two or more elements joined by chemical bonds.

Question 14

Which equation correctly calculates the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}$$

Question 15

Which of the following is a real-life example of a molecule held together by hydrogen bonds?

Accepted Answer

Water ($$H_2O)$$

Question 16

Which property of water is primarily due to hydrogen bonding?

Accepted Answer

Its high heat of vaporization.

Question 17

A molecule of $$CO_2 ($$carbon dioxide) is considered nonpolar because:

Accepted Answer

The molecule has a linear shape and the charge distribution is symmetrical.

Question 18

Which of the following statements about salts is correct?

Accepted Answer

Salts are ionic compounds formed from cations and anions.

Question 19

Which of the following best explains why atoms form chemical bonds?

Accepted Answer

To achieve a full valence shell and become more stable.

Question 20

Which of the following is true about polar covalent bonds?

Accepted Answer

Electrons are shared unequally, resulting in regions of partial charge.

The Chemical Level of Organization: Elements, Atoms, and Chemical Bonds in Human Anatomy & Physiology

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