Draw the Electron-Dot Structure of CaO and State the Type of Bonding: In Calcium Oxide (CaO), a calcium atom transfers its 2 valence electrons to an oxygen atom to form Ca²⁺ and O²⁻ ions held together by an ionic (electrovalent) bond.
Electron-Dot Structure of Calcium Oxide (CaO)
Step-by-Step Formation of CaO (Class 10 Science Chapter 3)
To draw the Lewis electron-dot structure of Calcium Oxide (CaO), first write the atomic number and electronic configuration of both elements:
| Element | Symbol | Atomic Number (Z) | Electronic Configuration (K, L, M, N) | Valence Electrons | Ion Formed |
|---|---|---|---|---|---|
| Calcium (Metal) | Ca | 20 | 2, 8, 8, 2 | 2 valence electrons | Ca²⁺ (loses 2e⁻ → 2, 8, 8) |
| Oxygen (Non-metal) | O | 8 | 2, 6 | 6 valence electrons | O²⁻ (gains 2e⁻ → 2, 8) |
- Calcium Atom (Ca): Calcium has atomic number 20 with electronic configuration 2, 8, 8, 2. It has 2 electrons in its outermost N-shell and loses these 2 electrons to achieve the stable argon octet configuration (2, 8, 8), forming a positively charged calcium cation (Ca²⁺).
- Oxygen Atom (O): Oxygen has atomic number 8 with electronic configuration 2, 6. It has 6 electrons in its outermost L-shell and needs 2 more electrons to complete its octet (2, 8), forming a negatively charged oxide anion (O²⁻).
- Electron Transfer Equation:
Ca: + ·Ö: ⟶ [Ca]²⁺ [:Ö:]²⁻ (or CaO) - Type of Bonding in CaO: Since the bond is formed by the complete transfer of two valence electrons from a metal (Calcium) to a non-metal (Oxygen), the type of bonding in CaO is Ionic Bonding (or Electrovalent Bonding).
Key Properties of Calcium Oxide (CaO) Due to Ionic Bonding
- Physical State: CaO is a hard, crystalline solid at room temperature because of strong electrostatic forces of attraction between Ca²⁺ and O²⁻ ions.
- High Melting & Boiling Point: A large amount of energy is required to break the strong inter-ionic attraction (melting point of CaO is 2850 K).
- Electrical Conductivity: Solid CaO does not conduct electricity, but it conducts electricity in the molten state or aqueous solution due to free-moving ions.
- For full textbook chapters, visit NCERT Class 10 Science Book PDF.
Frequently Asked Questions on Electron-Dot Structure of CaO
What type of bond is present in CaO (Calcium Oxide)?
Calcium Oxide (CaO) has an ionic bond (also called an electrovalent bond) formed by the complete transfer of two valence electrons from the metal Calcium (2,8,8,2) to the non-metal Oxygen (2,6).
Which ions are present in Calcium Oxide (CaO)?
Calcium Oxide consists of positively charged calcium cations (Ca²⁺) and negatively charged oxide anions (O²⁻) held together by strong electrostatic attraction.