Which Statement Below Correctly Describes an Ionic Compound?
An ionic compound is formed when a metal and a non-metal combine through an electrostatic attraction. This type of compound is characterized by the transfer of electrons from the metal to the non-metal, resulting in the formation of positively charged metal ions and negatively charged non-metal ions. The attraction between these oppositely charged ions creates a strong bond, giving ionic compounds their unique properties.
Statement 1: “An ionic compound consists of molecules held together by covalent bonds.”
This statement is incorrect. Ionic compounds are not made up of discrete molecules but rather a three-dimensional lattice structure. The positively and negatively charged ions are arranged in an alternating pattern, maximizing the attraction between them. Covalent compounds, on the other hand, are formed by the sharing of electrons between atoms, resulting in discrete molecules.
Statement 2: “Ionic compounds have high melting and boiling points.”
This statement is correct. Ionic compounds have strong electrostatic forces of attraction between their ions, requiring a significant amount of energy to break these bonds and change the state of the compound. As a result, ionic compounds generally have high melting and boiling points. For example, table salt (sodium chloride) has a melting point of 801°C and a boiling point of 1,413°C.
Statement 3: “Ionic compounds are good conductors of electricity in their solid state.”
This statement is incorrect. While ionic compounds are excellent conductors of electricity when dissolved in water or melted, they do not conduct electricity in their solid state. This is because the ions are locked in place in the lattice structure and cannot move to carry an electric charge. However, when dissolved or melted, the ions are free to move and conduct electricity.
Statement 4: “Ionic compounds are typically soluble in water.”
This statement is correct. Many ionic compounds are soluble in water due to the strong attraction between the ions and the polar water molecules. When an ionic compound dissolves in water, the water molecules surround and separate the ions, allowing them to move freely in solution. Examples of soluble ionic compounds include sodium chloride (NaCl) and potassium nitrate (KNO3).
Q: Are all ionic compounds solids at room temperature?
A: No, not all ionic compounds are solids at room temperature. Some ionic compounds, such as ammonium nitrate (NH4NO3), can exist as solids, liquids, or gases depending on the temperature and pressure conditions.
Q: Can ionic compounds conduct electricity in their molten state?
A: Yes, ionic compounds can conduct electricity when melted. In the molten state, the ions are free to move and carry an electric charge, allowing the compound to conduct electricity.
Q: Do ionic compounds have a definite ratio of cations to anions?
A: Yes, ionic compounds have a fixed ratio of cations to anions. This ratio is determined by the charges of the ions involved. For example, in sodium chloride (NaCl), there is always one sodium ion (Na+) for every chloride ion (Cl-).