Ionic Bonding and Compounds

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Questions and Answers

Explain the role of electronegativity difference in determining whether a bond between two atoms will be ionic or covalent.

A large electronegativity difference (typically greater than 1.7) indicates that one atom has a much stronger attraction for electrons than the other, leading to electron transfer and the formation of an ionic bond. A small electronegativity difference indicates a more equal sharing of electrons, resulting in a covalent bond.

Describe what happens to the electron configurations of sodium (Na) and chlorine (Cl) when they form an ionic bond to create sodium chloride (NaCl).

Sodium (Na) loses one electron to achieve a stable noble gas configuration, forming a Na+ ion with a positive charge. Chlorine (Cl) gains one electron to achieve a stable noble gas configuration, forming a Cl- ion with a negative charge.

Explain why solid ionic compounds are poor conductors of electricity, while molten ionic compounds are good conductors.

In solid ionic compounds, the ions are fixed in their lattice structure and cannot move freely to carry charge. When ionic compounds are melted, the ions are free to move and conduct electric current.

How does ionic size affect lattice energy, and why?

Smaller ion sizes lead to greater lattice energies because the ions can get closer together, resulting in stronger electrostatic attractions between the oppositely charged ions. Signup and view all the answers

Explain why ionic compounds tend to be brittle and shatter when struck.

When an ionic crystal is struck, ions of like charge can be forced into proximity. The resulting electrostatic repulsion causes the crystal to cleave along planes, leading to the shattering of the crystal. Signup and view all the answers

Describe the relationship between ionic charge and lattice energy. Provide an example to illustrate this relationship.

Higher ionic charges lead to greater lattice energies due to increased electrostatic attraction between the ions. For example, MgO, with Mg2+ and O2- ions, has a higher lattice energy than NaCl, with Na+ and Cl- ions. Signup and view all the answers

Explain why many ionic compounds are soluble in water despite the strong electrostatic forces holding them together.

Water is a polar solvent and can effectively solvate ions. Water molecules surround individual ions, weakening the ionic bonds and allowing the compound to dissolve. This process is called hydration. Signup and view all the answers

Compare the melting points of ionic and covalent compounds, and explain the reasons for the difference.

Ionic compounds generally have higher melting points than covalent compounds because the strong electrostatic forces between ions in the crystal lattice require more energy to overcome compared to the weaker intermolecular forces between covalent molecules. Signup and view all the answers

Explain how the transfer of electrons in ionic bonding leads to the formation of stable ions with noble gas configurations.

Atoms transfer electrons to achieve a stable octet (or duet for hydrogen), which is isoelectronic with a noble gas configuration. Metals lose electrons to achieve this stability, forming positive ions, while nonmetals gain electrons, forming negative ions. Signup and view all the answers

Consider the ionic compounds NaCl and KCl. Which would you expect to have a higher lattice energy, and why?

NaCl would be expected to have a higher lattice energy. Both compounds have the same charges (+1 and -1), but Na+ is smaller than K+. Smaller ionic radii lead to stronger electrostatic attractions and therefore higher lattice energies. Signup and view all the answers

Describe how electron transfer results in the formation of an ionic bond.

One atom transfers one or more electrons to another atom. This creates a positively charged ion (cation) and a negatively charged ion (anion). The electrostatic attraction between these oppositely charged ions forms the ionic bond. Signup and view all the answers

Explain the role of valence electrons in ionic bond formation.

Valence electrons are the electrons involved in chemical bonding. In ionic bonding, metals lose valence electrons to form cations, while nonmetals gain valence electrons to form anions, both achieving a stable electron configuration. Signup and view all the answers

Compare the electrical conductivity of an aqueous solution of an ionic compound with that of pure water. Explain the difference.

An aqueous solution of an ionic compound conducts electricity, while pure water does not (or conducts poorly). In the solution, the dissolved ions are free to move and carry charge, whereas pure water contains very few ions. Signup and view all the answers

How does the lattice energy relate to the stability of an ionic compound?

A higher lattice energy indicates stronger ionic bonds and a more stable ionic compound. More energy is required to break the compound into its constituent gaseous ions, meaning it is more stable. Signup and view all the answers

Explain how lattice energy influences the melting point of an ionic compound.

A higher lattice energy results in a higher melting point. Stronger ionic bonds require more thermal energy to overcome, thus a higher temperature is needed to transition from the solid to the liquid phase. Signup and view all the answers

Describe the process of electron transfer in the formation of potassium oxide (K₂O).

Each potassium atom (K) loses one electron to become K⁺. Oxygen (O) gains two electrons to become O²⁻. Two potassium ions (2K⁺) are required to balance the charge of one oxide ion (O²⁻), resulting in the formula K₂O. Signup and view all the answers

What are the key differences in the physical state (solid, liquid, gas) of ionic compounds versus covalent compounds at room temperature and pressure? Why do these differences occur?

Ionic compounds are typically solids at room temperature, while covalent compounds can be solids, liquids, or gases. This is because the strong electrostatic forces in ionic compounds require more energy to overcome, keeping them in a solid state, whereas covalent compounds have weaker intermolecular forces. Signup and view all the answers

If you have two ionic compounds, one with a large difference in ionic radii between the cation and anion and another with a smaller difference, which would likely have a higher lattice energy, assuming charges are equal? Explain.

The compound with the smaller difference in ionic radii would likely have a higher lattice energy. Smaller size allows the ions to be closer together, leading to greater electrostatic attraction and thus higher lattice energy. Signup and view all the answers

Explain why a large difference in electronegativity between two elements typically leads to the formation of an ionic bond rather than a covalent bond.

A large electronegativity difference means one element much more strongly attracts electrons. Instead of sharing (covalent), the more electronegative element effectively 'pulls' the electron(s) completely away from the other, resulting in ion formation and an ionic bond. Signup and view all the answers

How does the octet rule relate to the formation of ionic compounds?

Atoms in ionic compounds gain or lose electrons to achieve a full outer electron shell (octet) like noble gases. Metals lose electrons to achieve a stable octet in the previous shell, while nonmetals gain electrons to complete their valence shell to an octet. Signup and view all the answers

Flashcards

Ionic Compounds

Formed through ionic bonds between ions, typically involving a metal and a nonmetal. Overall charge must be neutral.

Electron Transfer

The fundamental process in ionic bonding where atoms transfer electrons to achieve a stable electron configuration.