Question 1

In a polar covalent bond, where are the shared electrons likely to be found?

Accepted Answer

Closer to the more electronegative atom. Electrons in a polar bond are pulled toward the atom with higher electronegativity, creating a dipole. This results in a partial negative charge on the more electronegative atom and a partial positive charge on the other. A molecule of hydrogen chloride ($HCl$) is a classic example of this polarity.

Question 2

Which scientist is primarily associated with the Lewis Dot structures used to represent bonding?

Accepted Answer

Gilbert N. Lewis. Gilbert N. Lewis introduced the dot notation to represent valence electrons and how they are shared in bonds. This system simplifies the visualization of the octet rule in covalent molecules. He also developed the theory of acids and bases based on electron pairs.

Question 3

What is the bond angle in a linear molecule like Carbon Dioxide ($CO_2$)?

Accepted Answer

180°. In carbon dioxide, the two double bonds stay as far apart as possible, resulting in a 180-degree angle. This linear geometry makes $CO_2$ a non-polar molecule despite having polar bonds. Many diatomic molecules also exhibit this straight-line arrangement.

Question 4

Which of the following contains a double covalent bond?

Accepted Answer

Oxygen ($O_2$). Each oxygen atom shares two pairs of electrons to complete its outer shell, forming a double bond. This bond is stronger and shorter than a single bond but weaker than a triple bond. Double bonds are common in many organic compounds like ethene.

Question 5

When a metal reacts with a non-metal, the metal atom typically?

Accepted Answer

Loses electrons and forms a cation. Metals have low ionization energies and tend to lose valence electrons during chemical reactions. By losing electrons, they form positively charged ions known as cations. Non-metals usually gain those electrons to form negatively charged anions.

Question 6

Which of the following is a non-polar molecule despite containing polar bonds?

Accepted Answer

Carbon Tetrachloride ($CCl_4$). Carbon tetrachloride is non-polar because its symmetrical tetrahedral shape causes the individual bond dipoles to cancel out. Even though the $C-Cl$ bonds are polar, the overall molecule has no net dipole moment. Symmetry is a key factor in determining molecular polarity.

Question 7

What name is given to the energy required to break one mole of a specific bond in a gaseous substance?

Accepted Answer

Bond enthalpy. Bond enthalpy, or bond energy, measures the strength of a chemical bond between two atoms. Higher bond enthalpy values indicate a more stable and stronger bond that is harder to break. This value is usually expressed in kilojoules per mole ($kJ/mol$).

Question 8

What is the hybridization of the carbon atom in an ethane ($C_2H_6$) molecule?

Accepted Answer

$sp^3$. Carbon in ethane forms four single sigma bonds, which requires $sp^3$ hybridization. This results in the characteristic tetrahedral geometry around each carbon atom. Hybridization theory explains how atomic orbitals mix to form new orbitals suitable for bonding.

Question 9

Which of the following forces is the weakest?

Accepted Answer

London dispersion forces. London dispersion forces are temporary dipole-induced dipole attractions found in all molecules. They are the weakest type of intermolecular force and depend on the movement of electrons. These forces are significant only when molecules are very close together.

Question 10

According to the Octet Rule, how many electrons does a Magnesium atom (Atomic Number 12) lose to become stable?

Accepted Answer

2. Magnesium has two electrons in its outermost shell and loses them to achieve the stable configuration of Neon. After losing these two electrons, it becomes a $Mg^{2+}$ ion. This loss of electrons is a typical behavior for Group 2 alkaline earth metals.

Periodic Table — Set 2