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

Question 1

Which statement best explains why sodium (Na) and chlorine (Cl) can combine to form sodium chloride (NaCl)?

Accepted Answer

Sodium donates an electron to chlorine, resulting in the formation of ions that attract each other to form an ionic bond.

Question 2

An atom of carbon-14 ($$^{14}C) $$has how many neutrons?

Accepted Answer

8 neutrons

Question 3

Which of the following best describes a compound?

Accepted Answer

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

Question 4

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

Accepted Answer

8 neutrons

Question 5

Which of the following is true about valence electrons?

Accepted Answer

They determine the chemical behavior of an atom.

Question 6

What is the maximum number of electrons that can occupy the second electron shell of an atom?

Accepted Answer

$$8$$

Question 7

Which type of chemical bond involves the sharing of valence electrons between atoms?

Accepted Answer

Covalent bond

Question 8

A neutral atom of oxygen has 8 protons. How many electrons does it have?

Accepted Answer

$$8$$

Question 9

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 10

Carbon-14 is used to date biological specimens because:

Accepted Answer

It is incorporated into organisms during metabolism and decays at a known rate after death.

Question 11

Which equation correctly represents the calculation of atomic mass?

Accepted Answer

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

Question 12

Which of the following statements about electron shells is correct?

Accepted Answer

Electrons occupy the lowest energy shell available.

Question 13

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

Accepted Answer

The bond between sodium and chlorine in table salt ($$NaCl)$$

Question 14

If an atom absorbs energy, what is most likely to happen to one of its electrons?

Accepted Answer

The electron moves to a higher energy shell.

Question 15

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

Accepted Answer

To fill their valence electron shells and achieve stability.

Question 16

Which of the following is NOT a type of chemical bond discussed in the study materials?

Accepted Answer

Metallic bond

Question 17

A molecule is defined as:

Accepted Answer

Two or more atoms held together by covalent bonds.

Question 18

Which of the following interactions is the weakest?

Accepted Answer

Van der Waals interaction

Question 19

If a biological sample contains $$1 	ext{g} of $$carbon-14, how much will remain after one half-life (about 5,000 years)?

Accepted Answer

$$0.5 	ext{g}$$

Question 20

Which principle is key to understanding the different kinds of chemical bonds?

Accepted Answer

Atoms are more stable when their valence shell is fully occupied with electrons.

Chapter 2: The Chemical Context of Life – Study Notes

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