The atomic number of an element is 8. How many electrons will it gain

The atomic number of an element is 8. How many electrons will it gain to form a compound with sodium?

One
Two
Three
Four
This question was previously asked in
UPSC NDA-2 – 2018
The element with atomic number 8 (Oxygen) will gain two electrons to form a compound with sodium.
– The element with atomic number 8 is Oxygen (O). Its electronic configuration is 2, 6.
– To achieve a stable octet configuration in its outermost shell, Oxygen needs to gain 8 – 6 = 2 electrons, forming the O²⁻ ion.
– Sodium (Na, atomic number 11) has electronic configuration 2, 8, 1 and tends to lose 1 electron to form the Na⁺ ion.
– In the formation of sodium oxide (Na₂O), two sodium atoms each lose one electron, and one oxygen atom gains two electrons.
Elements form chemical bonds (ionic or covalent) to achieve a stable electron configuration, usually a full valence shell (like noble gases). Oxygen is a non-metal in Group 16 and typically forms -2 ions by gaining two electrons. Sodium is an alkali metal in Group 1 and typically forms +1 ions by losing one electron.
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