Question 1

Which of the following statements best describes a compound?

Accepted Answer

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

Question 2

An atom of carbon 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 3

Which subatomic particle is responsible for determining the identity of an element?

Accepted Answer

Proton

Question 4

Radioactive isotopes are useful in medical imaging because they:

Accepted Answer

Decay spontaneously, giving off particles and energy that can be detected.

Question 5

Which of the following best explains why sodium chloride (NaCl) forms a crystal lattice?

Accepted Answer

Ionic bonds between cations and anions result in a repeating pattern of positive and negative charges.

Question 6

If an atom has 8 protons, 8 neutrons, and 10 electrons, what is its charge and what is it called?

Accepted Answer

Charge: -2, called an anion

Question 7

Which of the following best describes a polar covalent bond?

Accepted Answer

Atoms unequally share a pair of valence electrons due to differences in electronegativity.

Question 8

Given the electronegativity difference between two atoms is 1.2, what type of bond will they most likely form?

Accepted Answer

Polar covalent bond

Question 9

Which of the following statements about valence electrons is correct?

Accepted Answer

Valence electrons are found in the outermost shell and determine chemical reactivity.

Question 10

A neutral atom of magnesium has an atomic number of 12 and a mass number of 24. How many neutrons does it have?

Accepted Answer

$$24 - 12 = 12$$ neutrons

Question 11

Which of the following is true about elements with a full valence shell?

Accepted Answer

They are chemically inert and do not readily react with other elements.

Question 12

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

Accepted Answer

Ionic bonds involve the transfer of electrons, while covalent bonds involve the sharing of electrons.

Question 13

Which of the following best describes a cation?

Accepted Answer

A positively charged ion formed by the loss of electrons.

Question 14

A radioactive isotope of carbon ($$^{14}C) $$has 6 protons and 8 neutrons. What is its atomic mass?

Accepted Answer

$$6 + 8 = 14$$

Question 15

Which of the following scenarios best illustrates the concept of potential energy in an atom?

Accepted Answer

An electron in a higher energy shell has more potential energy than one in a lower shell.

Question 16

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

Accepted Answer

Table salt (sodium chloride)

Question 17

If two atoms have the same number of protons but different numbers of neutrons, they are:

Accepted Answer

Isotopes

Question 18

Which of the following best explains why elements in the same column of the periodic table have similar chemical properties?

Accepted Answer

They have the same number of valence electrons.

Question 19

A molecule of water (H$$_2O) is $$held together by which type of bond between its atoms?

Accepted Answer

Polar covalent bonds

Question 20

Which of the following is the correct formula for calculating the atomic mass of an atom?

Accepted Answer

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

Elements, Atoms, and Chemical Bonds: Foundations of General Biology

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