Q: Which equation correctly represents the calculation of an element’s mass number?

$$\text{Mass number} = \text{Number of protons} + \text{Number of neutrons}$$

Question 1

Which of the following best explains why sodium (Na) and chlorine (Cl) combine to form table salt (NaCl) with properties different from either element alone?

Accepted Answer

NaCl is a compound, and compounds have characteristics different from their constituent elements due to chemical bonding.

Question 2

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

Accepted Answer

Oxygen, carbon, hydrogen, and nitrogen

Question 3

What is the main difference between a covalent bond and an ionic bond?

Accepted Answer

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

Question 4

Refer to the diagram showing the transfer of an electron from one atom to another. What type of ions are formed and what type of bond results?

Accepted Answer

A cation and an anion are formed, resulting in an ionic bond.

Question 5

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 6

Which property of water is primarily responsible for its ability to form hydrogen bonds with ammonia (NH$$_3$$), as shown in the molecular diagram?

Accepted Answer

Water’s polarity due to its polar covalent bonds

Question 7

Which of the following statements about trace elements is correct?

Accepted Answer

Trace elements are required by organisms in minute quantities and are essential for life.

Question 8

Given the molecular models, which molecule is held together by a double covalent bond?

Accepted Answer

O$$_2$$

Question 9

Why are elements with a full valence shell chemically inert?

Accepted Answer

Their outermost electron shell is complete, so they do not tend to gain, lose, or share electrons.

Question 10

Which of the following best explains why the molecular shape of a biological molecule is important?

Accepted Answer

The shape determines how molecules recognize and respond to each other, affecting their function.

Question 11

Which equation correctly represents the calculation of an element’s mass number?

Accepted Answer

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

Question 12

Which of the following is a real-world example of an ionic compound and its structure, as shown in the images?

Accepted Answer

Table salt (NaCl), which forms a crystalline lattice structure

Question 13

Which of the following best describes the concept of electronegativity?

Accepted Answer

An atom’s attraction for the electrons in a covalent bond

Question 14

Which of the following is true about van der Waals interactions?

Accepted Answer

They are weak attractions that occur when electrons are unevenly distributed in molecules.

Question 15

A radioactive isotope differs from a stable isotope of the same element in which way?

Accepted Answer

It has a different number of neutrons and decays spontaneously, emitting particles and energy.

Question 16

Which of the following best explains why water is a polar molecule?

Accepted Answer

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

Question 17

Which of the following is the best example of a compound?

Accepted Answer

Sodium chloride (NaCl)

Question 18

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

Accepted Answer

The atomic number is the number of protons in the nucleus and defines the element.

Question 19

Which of the following best explains why the reversibility of weak bonds is advantageous in biological systems?

Accepted Answer

It allows biological molecules to interact temporarily and then separate as needed for cellular processes.

Question 20

Which of the following equations correctly represents the relationship between atomic mass and subatomic particles?

Accepted Answer

$$	ext{Atomic mass} \approx 	ext{Number of protons} + 	ext{Number of neutrons}$$

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

Guida di studio - Domande di pratica

Study guide - Flashcard