Topic 6 - Chemical Bonding

What happens during the formation of an ionic bond?

• Electrons are shared between two atoms

• Electrons are transferred from one atom to another

• Atoms share protons to form a bond

• Atoms merge their nuclei to form a new element

Answer explanation

During the formation of an ionic bond, electrons are transferred from one atom to another, resulting in the creation of charged ions that attract each other. This is different from sharing electrons, which occurs in covalent bonds.

Which pair of elements is most likely to form an ionic bond?

• Carbon and oxygen

• Hydrogen and hydrogen

• Sodium and chlorine

• Oxygen and nitrogen

Answer explanation

Sodium and chlorine are both highly reactive elements; sodium is a metal that loses an electron, while chlorine is a non-metal that gains an electron. This transfer of electrons leads to the formation of an ionic bond.

In a covalent bond, how are the electrons shared?

• Unequally between atoms with the same electronegativity

• Equally between atoms of different elements

• Unequally between atoms of different elements

• Equally between atoms of the same element

Answer explanation

In a covalent bond, electrons are shared equally between atoms of the same element because they have identical electronegativity, leading to a balanced distribution of electron density.

What type of bond is formed between two oxygen atoms in an O2 molecule?

• Ionic bond

• Covalent bond

• Metallic bond

• Hydrogen bond

Answer explanation

In an O2 molecule, two oxygen atoms share a pair of electrons, forming a covalent bond. This type of bond is characterized by the sharing of electron pairs between atoms, distinguishing it from ionic, metallic, and hydrogen bonds.

Which of the following is a characteristic of metallic bonding?

• Electrons are localized between two atoms

• Electrons are free to move throughout the structure

• Atoms are held together by the attraction between positive and negative ions

• Electrons are transferred from one atom to another

Answer explanation

In metallic bonding, electrons are not localized; instead, they are delocalized and free to move throughout the structure, allowing metals to conduct electricity and heat effectively.

Which compound contains both ionic and covalent bonds?

• NaCl

• CO2

• H2O

• NaOH

Answer explanation

NaOH contains both ionic and covalent bonds. The Na+ and OH- ions form an ionic bond, while the O-H bond within the hydroxide ion (OH-) is covalent. Other options contain only ionic (NaCl) or covalent (CO2, H2O) bonds.

What is the term for a covalent bond in which the electrons are shared unequally?

• Nonpolar covalent bond

• Ionic bond

• Polar covalent bond

• Metallic bond

Answer explanation

A polar covalent bond occurs when electrons are shared unequally between atoms, leading to partial charges. This contrasts with a nonpolar covalent bond, where electrons are shared equally.

What causes metallic bonding to be strong and malleable?

• The sharing of electrons between metal atoms

• The transfer of electrons from one metal atom to another

• The delocalization of electrons in the metal lattice

• The movement of protons within the metal structure

Answer explanation

The delocalization of electrons in the metal lattice allows for a 'sea of electrons' that can move freely, which contributes to the strength and malleability of metallic bonds, enabling metals to be shaped without breaking.

Which of the following bonds would have the highest melting point?

• A covalent bond between carbon atoms

• An ionic bond between sodium and chloride ions

• A metallic bond between copper atoms

• A covalent bond between hydrogen and oxygen atoms

Answer explanation

An ionic bond between sodium and chloride ions has the highest melting point due to the strong electrostatic forces between the oppositely charged ions, which require more energy to break compared to covalent or metallic bonds.

What is the shape of a molecule with two bonding pairs and two lone pairs, like H2O?

• Linear

• Tetrahedral

• Bent

• Trigonal planar

Answer explanation

The shape of a molecule with two bonding pairs and two lone pairs, like H2O, is bent. The lone pairs repel the bonding pairs, causing the molecule to adopt a bent geometry rather than a linear or tetrahedral shape.