Question

Which of the following statements about ionic bonds is not true? a. They cannot exist without water molecules. b. They are not the same as hydrogen bonds. c. They involve electrical attraction between atoms with opposite charge. d. They are not as strong as covalent bonds.

Short answer

Statement (a) is not true.

Step-by-step solution

Understand the nature of ionic bonds

Ionic bonds are formed when one atom donates an electron to another, resulting in a positive ion and a negative ion that attract each other. This electric attraction is the basis of the bond.

Evaluate statement (a)

Consider if ionic bonds can exist without water. Ionic bonds form in solid ionic compounds and do not need water to exist. Water can dissolve ionic compounds into ions, but it isn’t required for their formation.

Evaluate statement (b)

Recognize the differences between ionic bonds and hydrogen bonds. Ionic bonds involve the complete transfer of electrons and the resulting electric attraction between ions, while hydrogen bonds are weaker interactions typically involving a hydrogen atom.

Evaluate statement (c)

Validate that ionic bonds involve electrical attraction between atoms with opposite charges. This is by definition true as positive and negative ions attract each other as part of ionic bonding.

Evaluate statement (d)

Compare the strength of ionic bonds to covalent bonds. Covalent bonds, which involve sharing electrons, are generally considered stronger than ionic bonds.

Determine the incorrect statement

After evaluating all statements, it’s clear that statement (a) is not true because ionic bonds can and do exist without water molecules.

Key concepts

Electron Transfer

When we talk about ionic bonds, the first thing to understand is the process of electron transfer. This occurs when one atom gives up one or more of its electrons to another atom. The atom that loses electrons becomes a positively charged ion, known as a cation. Meanwhile, the atom that gains electrons becomes a negatively charged ion, known as an anion. This transfer of electrons allows the atoms to achieve a more stable electronic configuration, often resembling the electronic structure of noble gases.

To break it down simply:

• A cation forms when an atom loses electrons (+ charge).
• An anion forms when an atom gains electrons (- charge).

Understanding this process is crucial for grasping how ionic bonds form in the first place.

Electrical Attraction

After the electron transfer, the resulting ions (cations and anions) are attracted to each other by electrical force, also known as Coulomb force. This attraction occurs because opposite charges attract each other. This electric attraction is what holds the ions together, forming an ionic bond.

Here’s a simplified view:

• Ions with opposite charges (positive and negative) are pulled toward each other by this electrical attraction.
• This force of attraction keeps the ions tightly bound in an ionic compound.

Electric attraction thus plays a key role in the structure and stability of ionic compounds.

Ionic Compounds

When ions bond together through electrical attraction, they form ionic compounds. These compounds usually consist of a metal and a non-metal. They have distinctive properties that include:

• High melting and boiling points due to the strength of their ionic bonds.
• Ability to conduct electricity when melted or dissolved in water, as the ions are free to move.
• They often form crystalline structures because of the orderly arrangement of ions.

One key thing to remember is that ionic compounds are not dependent on water. They can form and stay stable outside of water, although many can dissolve in water to separate into individual ions.

Covalent Bonds

Unlike ionic bonds, covalent bonds involve the sharing of electrons between atoms rather than transferring them. This typically occurs between non-metal atoms.

Key aspects of covalent bonds include:

• Atoms share pairs of electrons to fill their outermost shells and achieve stable configurations.
• Covalent bonds can create molecules with specific geometric shapes.
• These bonds are generally stronger than ionic bonds and result in the formation of molecules, not ions.

Because of electron sharing, covalent bonds result in different chemical and physical properties than ionic bonds.

Hydrogen Bonds

Hydrogen bonds are much weaker interactions compared to ionic or covalent bonds. They occur when a hydrogen atom, which is covalently bonded to a highly electronegative atom (like oxygen, nitrogen, or fluorine), experiences an attraction to another electronegative atom.

Important points about hydrogen bonds include:

• Hydrogen bonds explain many properties of water, like its high boiling point and surface tension.
• They play a critical role in the structure and functioning of biomolecules such as DNA and proteins.
• Hydrogen bonds are not as strong as ionic or covalent bonds, but they are crucial in maintaining the structure and function of various biological molecules.

Understanding the differences between these bonds helps clarify why ionic bonds are unique and distinct in their formation and properties.