Question 1

How many electrons participate in a triple covalent bond?
A) 3
B) 6
C) 9
D) 12

Accepted Answer

A triple covalent bond involves the sharing of three pairs of electrons, with each pair consisting of two electrons, totaling six electrons participating in the bond.

Question 2

Which of the following statements correctly describes any chemical reaction that has reached equilibrium?
A) The concentrations of products and reactants are equal.
B) The reaction is now irreversible.
C) Both forward and reverse reactions have halted.
D) The rates of the forward and reverse reactions are equal.

Accepted Answer

At equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction, meaning that the system is dynamically balanced, not that the reactions have stopped or that concentrations are necessarily equal.

Question 3

Which of the following factors contribute to the tetrahedral shape of the above molecule?
A) the shape of the two p orbitals in the carbon atom
B) the shape of the one s orbital in the carbon atom
C) the shape of the sp3 hybrid orbitals of the electrons shared between the carbon and hydrogen atoms
D) hydrogen bonding configurations between the carbon and hydrogen atoms

Accepted Answer

The answer of  Which of the following factors contribute...

Question 4

An atom has four electrons in its valence shell. What types of covalent bonds is it capable of forming?
A) single, double, or triple
B) single and double only
C) single bonds only
D) double bonds only

Accepted Answer

An atom with four electrons in its valence shell can form single, double, or triple covalent bonds by sharing one, two, or three pairs of electrons, respectively, with other atoms to achieve a stable electron configuration.

Question 5

The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound. A) HS B) HS2 C) H₂S D) H4S

Accepted Answer

Sulfur has 6 valence electrons and needs 2 more to complete its octet. It forms two covalent bonds with two hydrogen atoms, each providing one electron, resulting in the molecular formula H₂S.

Question 6

Which one of the following describes the correct trends in electronegativity in the periodic table?
A) increases across a period and decreases down a group
B) decreases across a period and decreases down a group
C) increases across a period and increases down a group
D) decreases across a period and increases down a group

Accepted Answer

Electronegativity increases across a period due to the increasing nuclear charge, which attracts the bonding pair of electrons more strongly. It decreases down a group as the atomic radius increases, making the attraction between the nucleus and the bonding pair of electrons weaker.

Question 7

Which of the following factors will increase the rate of reaction in the forward direction?
A) addition of nitrogen
B) addition of ammonia
C) addition of hydrogen
D) addition of both nitrogen and hydrogen

Accepted Answer

Adding both nitrogen and hydrogen to a reaction involving their combination (such as the Haber process for ammonia synthesis) increases the concentration of reactants, thereby increasing the rate of the forward reaction according to Le Chatelier's principle.

Question 8

If an atom has a charge of +1, which of the following must be true?
A) It has two more protons than neutrons.
B) It has the same number of protons as electrons.
C) It has one more electron than it does protons.
D) It has one more proton than it does electrons.

Accepted Answer

An atom with a charge of +1 means it has one more proton than electrons. The number of neutrons is not directly related to the charge of an atom. Choices A, B, and C do not accurately describe an atom with a +1 charge.

Question 9

Which statement is true of all atoms that are anions?
A) The atom has more electrons than protons.
B) The atom has more protons than electrons.
C) The atom has fewer protons than does a neutral atom of the same element.
D) The atom has more neutrons than protons.

Accepted Answer

Anions are negatively charged ions, which means they have gained extra electrons compared to the number of protons they have. This results in a net negative charge.

Question 10

The reactivity of an atom arises from ________.
A) the average distance of the outermost electron shell from the nucleus
B) the existence of unpaired electrons in the valence shell
C) the sum of the potential energies of all the electron shells
D) the potential energy of the valence shell

Accepted Answer

The reactivity of an atom primarily arises from the presence of unpaired electrons in the valence shell, as these unpaired electrons can easily participate in chemical bonds with other atoms.

Question 11

How is a covalent bond formed?
A) two atoms share two pairs of electrons
B) two atoms share two electrons
C) two atoms share one electron
D) one atom loses a pair of electrons to the other

Accepted Answer

A covalent bond is formed when two atoms share a pair of electrons.

Question 12

Which of the following correctly describes chemical equilibrium?
A) Forward and reverse reactions continue with no net effect on the concentrations of the reactants and products.
B) Concentrations of products are higher than the concentrations of the reactants.
C) There are equal concentrations of products and reactants while forward and reverse reactions continue.
D) There are equal concentrations of reactants and products, and the reactions have stopped.

Accepted Answer

Chemical equilibrium is characterized by the forward and reverse reactions occurring at the same rate, resulting in no net change in the concentrations of reactants and products, even though both reactions continue to occur.

Question 13

Which of the following types of representation would work best to indicate the type and number of atoms in a molecule?
A) molecular formula
B) structural formula
C) ball-and-stick model
D) space-filling model

Accepted Answer

A molecular formula works best to indicate the type and number of atoms in a molecule as it provides a simple notation that shows exactly how many atoms of each element are present in the molecule, without detailing the arrangement of those atoms.

Question 14

In the term trace element, the adjective trace means that ________.
A) the element is required in very small amounts
B) the element can be used as a label to trace atoms through an organism's metabolism
C) the element is very rare on Earth
D) the element enhances health but is not essential for the organism's long-term survival

Accepted Answer

Trace elements are required by an organism in only minute quantities, which is what the term "trace" implies in this context.

Question 15

What is the atomic number of the cation formed in the reaction in the illustration?
A) 8
B) 10
C) 11
D) 16

Accepted Answer

The atomic number of a cation does not change during the formation of the ion. It remains the same as the atomic number of the neutral atom from which the cation is formed. The atomic number is the number of protons in an atom's nucleus, and this number defines the chemical element. In the formation of a cation, an atom loses one or more electrons but the number of protons (and thus the atomic number) remains unchanged.

Question 16

We can represent atoms by listing the number of protons, neutrons, and electrons-for example, 2p+, 2n0, 2e- for helium. Which of the following represents the 18O isotope of oxygen?
A) 7p+, 2n0, 9e-
B) 8p+, 10n0, 8e-
C) 9p+, 9n0, 9e-
D) 10p+, 8n0, 9e-

Accepted Answer

The 18O isotope of oxygen has 8 protons (as all oxygen atoms do), 10 neutrons (to make the mass number 18), and 8 electrons (to balance the 8 positive charges of the protons for a neutral atom).

Question 17

Elements found in the first two columns of the periodic table contain outer electron shells that are ________; these elements tend to form ________ in solution.
A) almost empty; cations
B) almost empty; anions
C) almost full; cations
D) almost full; anions

Accepted Answer

The elements in the first two columns of the periodic table have one or two electrons in their outer shells, making these shells almost empty. These elements tend to lose these electrons to achieve a stable electronic configuration, forming positively charged ions or cations in solution.

Question 18

Nitrogen (N) normally forms three covalent bonds with a valence of five. However, ammonium has four covalent bonds, each to a different hydrogen (H) atom (H has a valence of one). What do you predict to be the charge on ammonium?
A) +1
B) -1
C) +2
D) -2

Accepted Answer

Nitrogen, with a valence of five, forms four covalent bonds in ammonium, sharing an extra pair of electrons than it normally does. This results in a positive charge, making the ammonium ion (NH4+) have a charge of +1.

Question 19

Compared with 31P, the radioactive isotop 32P has ________.
A) a different atomic number
B) one more proton
C) one more electron
D) one more neutron

Accepted Answer

32P has the same atomic number as 31P, meaning it has the same number of protons and electrons but differs by one neutron, making it a different isotope.

Question 20

Which of the following is true for the above reaction?
A) the reaction is nonreversible
B) hydrogen and nitrogen are the reactants of the reverse reaction
C) ammonia is being formed and decomposed simultaneously
D) only the forward or reverse reactions can occur at one time

Accepted Answer

Ammonia is being formed and decomposed simultaneously

Quiz 2: Atoms and Molecules

How many electrons participate in a triple covalent bond?

Which of the following statements correctly describes any chemical reaction that has reached equilibrium?

Which of the following factors contribute to the tetrahedral shape of the above molecule?

An atom has four electrons in its valence shell. What types of covalent bonds is it capable of forming?

The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound.

Which one of the following describes the correct trends in electronegativity in the periodic table?

Which of the following factors will increase the rate of reaction in the forward direction?

If an atom has a charge of +1, which of the following must be true?

Which statement is true of all atoms that are anions?

The reactivity of an atom arises from ________.

How is a covalent bond formed?

Which of the following correctly describes chemical equilibrium?

Which of the following types of representation would work best to indicate the type and number of atoms in a molecule?

In the term trace element, the adjective trace means that ________.

What is the atomic number of the cation formed in the reaction in the illustration?

We can represent atoms by listing the number of protons, neutrons, and electrons-for example, 2p+, 2n0, 2e- for helium. Which of the following represents the 18O isotope of oxygen?

Elements found in the first two columns of the periodic table contain outer electron shells that are ; these elements tend to form in solution.

Nitrogen (N) normally forms three covalent bonds with a valence of five. However, ammonium has four covalent bonds, each to a different hydrogen (H) atom (H has a valence of one) . What do you predict to be the charge on ammonium?

Compared with 31P, the radioactive isotop 32P has ________.

Which of the following is true for the above reaction?