IBSL Chemistry Topic 4 Bonding Multiple Choice Questions

Sodium carbonate contains both covalent and ionic bonds. The compound is made up of sodium ions (Na+) and carbonate ions (CO3^2-). The bond between sodium and carbonate is ionic, as sodium donates an electron to carbonate, resulting in the formation of an ionic bond. However, within the carbonate ion itself, the carbon-oxygen bonds are covalent, as the electrons are shared between the carbon and oxygen atoms. Therefore, sodium carbonate contains both types of bonds.

The Valence Shell Electron Pair Repulsion (VSEPR) Theory is used to predict the shapes of molecules and ions. This theory states that electron pairs in the valence shell of an atom repel each other and therefore arrange themselves in a way that maximizes the distance between them. By considering the number of electron pairs around the central atom and their repulsion, the VSEPR theory allows us to determine the most likely shape of a molecule or ion. This is important in understanding the properties and behavior of chemical compounds.

CO2 is a linear molecule because it consists of two oxygen atoms bonded to a central carbon atom. The carbon-oxygen double bonds are arranged in a straight line, resulting in a linear molecular shape. The other molecules listed, SO2, H2S, and Cl2O, have a bent or angular shape due to the presence of lone pairs or different atom arrangements.

P and O are most likely to form a covalently bonded compound because both elements have relatively high electronegativity values. Covalent bonding occurs when atoms share electrons, and elements with similar electronegativity values are more likely to share electrons equally. In the case of P and O, both elements have a strong attraction for electrons, making it likely that they will form a covalent bond by sharing electrons between them.

When element X from Group 2 reacts with element Y from Group 7, they will form an ionic compound. Group 2 elements lose 2 electrons to achieve a stable octet configuration, forming a 2+ cation. Group 7 elements gain 1 electron to achieve a stable octet configuration, forming a 1- anion. Therefore, element X will form X2+ cations and element Y will form Y- anions in the compound formed when they react together.

The bond between O and H in H2O would be the most polar because the electronegativity difference between O and H is the largest compared to the other bond options. Oxygen (O) has an electronegativity of 3.5, while hydrogen (H) has an electronegativity of 2.2. The greater the electronegativity difference between two atoms, the more polar the bond between them becomes. Therefore, the O-H bond in H2O is the most polar.

Hydrogen bonding occurs when hydrogen is bonded to a highly electronegative atom such as oxygen, nitrogen, or fluorine. In option II, water (H2O) is present, which contains hydrogen bonded to oxygen atoms. This allows for hydrogen bonding to occur between water molecules. In options I and III, there is no mention of substances that contain hydrogen bonded to highly electronegative atoms, so hydrogen bonding would not be expected to occur. Therefore, the correct answer is II only.

As the number of bonds between two atoms increases, the bond length decreases. This is because the atoms are held closer together, resulting in a shorter bond length. Additionally, the bond strength increases because more bonds between atoms require more energy to break them apart. Therefore, the correct answer is that bond length decreases and bond strength increases.

Most ionic compounds have high melting and boiling points because they are held together by strong electrostatic forces of attraction between positively and negatively charged ions. These forces require a significant amount of energy to overcome, resulting in high melting and boiling points.

Based on the given information, the solid conducts heat and electricity, which suggests the presence of delocalized electrons that can move freely within the solid. Additionally, the solid does not dissolve in water or organic solvents, indicating a strong bond between its particles. These characteristics are consistent with metallic bonding, where positively charged metal ions are held together by a sea of delocalized electrons. Therefore, the most likely bond between the particles in this solid is metallic.

H2(g) has the lowest electrical conductivity because it is a non-metal and does not have any free-moving charged particles. Cu(s) is a metal and has high electrical conductivity due to the presence of delocalized electrons. Hg(l) is also a metal and has relatively high electrical conductivity. LiOH(aq) is an ionic compound that dissociates into Li+ and OH- ions in solution, allowing for the flow of charged particles and therefore higher electrical conductivity than H2(g).

CO2 is a linear molecule with two oxygen atoms bonded to a central carbon atom. The electronegativity difference between carbon and oxygen is significant, causing the C=O bond to be polar. However, the molecule as a whole is non-polar due to its symmetrical geometry. The two polar bonds cancel each other out, resulting in a non-polar molecule.

The boiling point of a substance is determined by the strength of the intermolecular forces between its molecules. Hydrogen bonding is a strong intermolecular force that occurs when a hydrogen atom is bonded to a highly electronegative atom (such as nitrogen, oxygen, or fluorine) and is attracted to another electronegative atom in a different molecule. NH3 can form hydrogen bonds between its nitrogen atom and the hydrogen atoms of neighboring NH3 molecules, which increases the strength of the intermolecular forces and raises its boiling point. On the other hand, PH3 does not have hydrogen bonding because phosphorus is less electronegative than nitrogen, resulting in weaker intermolecular forces and a lower boiling point.

The H-N-H bond angles in NH2- are smaller than in NH3 because NH2- has a lone pair of electrons that repel the bonding pairs, causing the bond angle to decrease. NH3 has a larger bond angle than NH2- because it has one less lone pair of electrons, reducing the repulsion between the bonding pairs. NH4+ has the largest bond angle because it has no lone pairs of electrons, resulting in the least repulsion between the bonding pairs. Therefore, the correct order is NH2-

The correct answer is H2O, NH3, CH4. This is because the given compounds are listed in alphabetical order.

Covalent bonds are the strongest type of chemical bond, as they involve the sharing of electrons between atoms. Hydrogen bonds are weaker than covalent bonds but still stronger than Van der Waals' forces. Hydrogen bonds occur when a hydrogen atom is attracted to a highly electronegative atom, such as oxygen or nitrogen. Van der Waals' forces are the weakest type of bond and are caused by temporary fluctuations in electron distribution, resulting in temporary positive and negative charges. Therefore, the correct order of bond strength is Covalent> Hydrogen> Van der Waals'.

CH3CH2OH (ethanol) is the most soluble substance in water at 298K. This is because ethanol can form hydrogen bonds with water molecules through its hydroxyl (-OH) group. The hydroxyl group is polar and can attract the partially positive hydrogen atoms in water, allowing for strong intermolecular attractions and high solubility. In contrast, the other substances listed (CH3CH3, CH3OCH3, and CH3CH2CH2CH2OH) do not have hydroxyl groups and cannot form hydrogen bonds with water to the same extent, resulting in lower solubility.

The energy absorbed when copper metal melts is used to overcome the non-directional metallic bonds between the copper atoms. Metallic bonds are formed between metal atoms, where the valence electrons are delocalized and free to move throughout the structure. When copper metal melts, the energy absorbed is used to break these metallic bonds, allowing the copper atoms to move freely and take on a liquid form. This is different from the other options, which involve breaking covalent, ionic, or forming ionic bonds.

SO3 is a non-polar molecule because it consists of three oxygen atoms bonded to a central sulfur atom. The sulfur-oxygen bonds are polar due to the difference in electronegativity between sulfur and oxygen. However, the molecule is trigonal planar in shape, with the oxygen atoms arranged symmetrically around the sulfur atom. This arrangement cancels out the dipole moments of the polar bonds, resulting in a molecule with no overall dipole moment and therefore non-polar.

The boiling point of a substance is determined by the strength of the intermolecular forces between its molecules. In the given options, C2H6 (ethane) and C3H8 (propane) are both hydrocarbons, but C3H8 has a higher molecular weight and therefore stronger intermolecular forces. Since stronger forces require more energy to break and reach the boiling point, C3H8 has a higher boiling point than C2H6. Therefore, the second substance (C3H8) has a higher boiling point than the first substance (C2H6).

The boiling point of a substance is determined by the strength of intermolecular forces between its molecules. In the given options, C2H6 (ethane) has the highest molar mass, which means it has the most number of electrons and a larger surface area compared to the other compounds. This results in stronger London dispersion forces between its molecules, leading to a higher boiling point. Therefore, the boiling point of C2H6 is expected to be higher compared to CH3F (fluoromethane) and CH3OH (methanol).