When magnesium and oxygen form a compound together, what happens?
Select one:
a. Magnesium forms a negative anion, and oxygen forms a positive cation
b. Magnesium remains neutral and oxygen forms a negative anion
c. Magnesium forms a positive cation, and oxygen forms a negative anion
d. Magnesium and oxygen share electrons in a covalent bond
The correct answer and explanation is :
The correct answer is:
c. Magnesium forms a positive cation, and oxygen forms a negative anion.
Explanation:
When magnesium (Mg) and oxygen (O) react to form a compound, they undergo ionic bonding, which involves the transfer of electrons. Magnesium is a metal from Group 2 of the periodic table, meaning it has two valence electrons. Oxygen is a nonmetal from Group 16 and has six valence electrons, requiring two more electrons to complete its octet.
During the reaction:
- Magnesium donates its two valence electrons to oxygen, becoming a positively charged cation (Mg²⁺).
- Oxygen accepts these two electrons, completing its octet and becoming a negatively charged anion (O²⁻).
- These oppositely charged ions attract each other, forming an ionic bond and creating magnesium oxide (MgO).
This process follows the octet rule, which states that atoms tend to gain, lose, or share electrons to achieve a full outer shell, similar to noble gases. The transfer of electrons from magnesium to oxygen results in a strong electrostatic force between the ions, forming a stable crystalline structure.
Why are the other options incorrect?
- Option a: Incorrect because magnesium does not form a negative anion, and oxygen does not form a positive cation. Metals lose electrons (becoming cations), while nonmetals gain electrons (becoming anions).
- Option b: Incorrect because magnesium does not remain neutral; it loses electrons and becomes Mg²⁺.
- Option d: Incorrect because magnesium and oxygen do not share electrons (which would indicate a covalent bond). Instead, they form an ionic bond through electron transfer.
This is a fundamental concept in chemistry, demonstrating how metals and nonmetals interact to form stable ionic compounds.
