Summary
Ionic compounds are formed when a metal reacts with a non-metal, resulting in the transfer of electrons and the formation of ions. Cation — a positive ion formed when an atom loses electrons. Example: Sodium (Na) loses one electron to form Na⁺. Anion — a negative ion formed when an atom gains electrons. Example: Chlorine (Cl) gains one electron to form Cl⁻. Ionic Bond — a strong electrostatic attraction between oppositely charged ions. Example: Sodium Chloride (NaCl). Lattice Structure — a regular arrangement of alternating positive and negative ions held together by strong electrostatic forces. Example: Sodium Chloride (NaCl).
Exam Tips
Key Definitions to Remember
- An ion is an atom or group of atoms with a positive or negative charge.
- An ionic bond is a strong electrostatic attraction between oppositely charged ions.
Common Confusions
- Confusing ionic bonds with covalent bonds, which involve sharing electrons.
- Forgetting that ionic compounds conduct electricity only when molten or in solution, not when solid.
Typical Exam Questions
- What is a cation? A positive ion formed when an atom loses electrons.
- How is an ionic bond formed between Group I and Group VII elements? Group I elements lose an electron to form a +1 ion, and Group VII elements gain an electron to form a -1 ion.
- Why do ionic compounds have high melting points? Due to the strong electrostatic forces of attraction in the lattice structure.
What Examiners Usually Test
- The ability to describe the formation of ionic bonds using dot-and-cross diagrams.
- Understanding the properties of ionic compounds, such as electrical conductivity and melting points.