Question 1

How many electrons participate in a triple covalent bond?

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?

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?

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?

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.

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?

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?

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?

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?

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 ________.

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?

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?

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?

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 ________.

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?

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?

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.

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?

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 ________.

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?

Accepted Answer

Ammonia is being formed and decomposed simultaneously

Quiz 2: Atoms and Molecules