27. (a) An element 'A' has atomic number 12 and element 'B' has atomic number 8.
What type of bond they will form? Give reason for your answer. (b) Explain the property of the compound formed by elements A and B with respect to its electrical conductivity.
What type of bond they will form? Give reason for your answer. (b) Explain the property of the compound formed by elements A and B with respect to its electrical conductivity.
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Answer:
(a) Element 'A' with atomic number 12 refers to magnesium (Mg), and element 'B' with atomic number 8 refers to oxygen (O).
Magnesium (Mg) is a metal, and oxygen (O) is a non-metal. When a metal and a non-metal combine, they typically form an ionic bond.
Ionic bond: An ionic bond is formed when one or more electrons are transferred from the metal atom to the non-metal atom. This transfer results in the formation of positively charged metal ions (cations) and negatively charged non-metal ions (anions). The electrostatic attraction between these oppositely charged ions holds the compound together.
In the case of magnesium (Mg) and oxygen (O), magnesium tends to lose two electrons to achieve a stable electron configuration similar to the nearest noble gas, neon. Oxygen, on the other hand, tends to gain two electrons to achieve a stable electron configuration like the nearest noble gas, helium.
Magnesium (Mg): 2, 8, 2 --> Loses 2 electrons --> 2, 8
Oxygen (O): 2, 6 --> Gains 2 electrons --> 2, 8
The ionic compound formed between magnesium and oxygen is magnesium oxide (MgO), where magnesium is in the form of Mg²⁺ cations, and oxygen is in the form of O²⁻ anions. The chemical formula for magnesium oxide is MgO.
(b) Electrical conductivity of the compound formed by elements A (magnesium) and B (oxygen) depends on the type of bond they form.
Magnesium oxide (MgO) is an ionic compound, which means it has a crystal lattice structure composed of positively charged magnesium ions (Mg²⁺) and negatively charged oxide ions (O²⁻). In the solid-state, ionic compounds like MgO do not conduct electricity because the ions are held in fixed positions within the lattice, and there are no free-moving charged particles to carry an electric current.
However, in the molten state (when it is melted) or when dissolved in water (forming an aqueous solution), the crystal lattice breaks down, and the ions become free to move. In this state, magnesium oxide can conduct electricity because the mobile ions can carry electric charges, enabling the flow of electric current