Question 1

Which of the following elements does not have at least two differently charged cations?

Accepted Answer

Magnesium typically forms a +2 cation and does not commonly exhibit multiple oxidation states, unlike copper, cobalt, and iron, which can form cations with different charges.

Question 2

Water, H₂O and hydrogen peroxide, H₂O₂, have identical properties.

Accepted Answer

Water and hydrogen peroxide have different properties due to the presence of an extra oxygen atom in hydrogen peroxide. Hydrogen peroxide is a strong oxidizing agent and can cause skin irritation, while water is not an oxidizing agent and is essential for life.

Question 3

In its ground state, sulfur has two valence electrons and needs four more electrons to reach the octet.

Accepted Answer

In its ground state, sulfur has six valence electrons and needs two more electrons to reach the octet.

Question 4

Elements that belong to the same group have the same number of valence electrons.

Accepted Answer

This is one of the defining characteristics of groups in the periodic table. Elements in the same group have the same number of valence electrons, which determines their chemical behavior and reactivity.

Question 5

Sulfur and chlorine have the same number of valence electrons.

Accepted Answer

Sulfur has six valence electrons (it is in Group 16 of the periodic table), while chlorine has seven valence electrons (it is in Group 17 of the periodic table).

Question 6

When covalent bonds are broken energy is released.

Accepted Answer

When covalent bonds are broken, energy is required or absorbed, rather than released.

Question 7

Calcium and barium have the same number of valence electrons.

Accepted Answer

Calcium and barium both belong to the same group in the periodic table (group 2), which means they have the same number of valence electrons (two).

Question 8

Which of the following formulas includes a parenthesis?

Accepted Answer

Aluminum nitrate is written as Al(NO3)3, which includes parentheses around the NO3 group.

Question 9

Which of the following elements has at least two differently charged cations?

Accepted Answer

Cobalt has at least two differently charged cations, Co2+ and Co3+. Magnesium, calcium, and lithium only have one cation each with a fixed charge (Mg2+, Ca2+, Li+).

Question 10

A single bond is always represented by two electrons.

Accepted Answer

A single bond is a covalent bond where two atoms share a pair of electrons, so each atom contributes one electron to the bond. Thus, a single bond is represented by two electrons.

Question 11

The electronegativity of chlorine is 3.0 while that of iodine is 2.5. The correct way of writing the formula of a molecule composed of one chlorine and one iodine atoms and the corresponding name are ________.

Accepted Answer

The element with the lower electronegativity is usually listed first in the formula, so the correct formula is ICl, which is iodine monochloride. A and B are incorrect because they list chlorine first in the formula. D is incorrect because it uses a nonstandard naming convention.

Question 12

A covalent bond is formed by the sharing of the innermost electrons.

Accepted Answer

A covalent bond is formed by the sharing of outermost electrons.

Question 13

Only helium among the Group VIIIA elements has two valence electrons.

Accepted Answer

Helium is in Group VIIIA (noble gases) and has two valence electrons, as it has an electron configuration of 1s². Other noble gases have eight valence electrons.

Question 14

A single, neutral chlorine atom has seven valence electrons.

Accepted Answer

A neutral chlorine atom has 17 electrons total, and its electron configuration is 2-8-7, meaning it has seven valence electrons in the outermost energy level.

Question 15

Which of the following formulas does not include a parenthesis?

Accepted Answer

The formula for sodium dichromate is Na2Cr2O7 and does not include any parentheses. The formulas for ammonium carbonate (NH4)2CO3, aluminum bicarbonate Al(HCO3)3, and magnesium dihydrogen phosphate Mg(H2PO4)2 all include parentheses.

Question 16

Energy is released as two atoms, such as two hydrogen atoms, form, a bond.

Accepted Answer

When two atoms form a bond, energy is released in the form of a chemical reaction. This energy is known as bond energy, and it is released as the atoms share electrons and become more stable.

Question 17

Natural sugars are broken down into glucose in our body.

Accepted Answer

Natural sugars, such as those found in fruits and vegetables, contain sucrose, fructose, and glucose. When they are broken down in our body, they are converted into glucose.

Question 18

Elements that belong to the same period have the same number of valence electrons.

Accepted Answer

Elements that belong to the same period have different numbers of valence electrons. Valence electrons increase by one from left to right in a period, but remain the same in a group.

Question 19

Covalent bonds are formed between atoms that share pairs of electrons.

Accepted Answer

Covalent bonds involve the sharing of electrons between atoms to achieve a stable electron configuration.

Question 20

Which of the following anions has the largest number of oxygen atoms and at the same time has the most negative charge?

Accepted Answer

Phosphate (PO4) has the largest number of oxygen atoms (four) and a negative charge of -3, making it the anion with the most negative charge. Carbonate (CO3) has three oxygen atoms and a charge of -2, permanganate (MnO4) has four oxygen atoms and a charge of -1, and chromate (CrO4) has four oxygen atoms and a charge of -2.

Quiz 5: Chemical Bonding and Nomenclature