Question

which element would have a full outer shell of electrons if it gained three electrons? (1 point)
argon
nitrogen
lithium
boron

Explanation:

Step1: Analyze electron - configuration of boron

Boron has 5 electrons. Its electron - configuration is 1s²2s²2p¹. If it gains 3 electrons, it will have 8 electrons and a full outer shell (2s²2p⁶).

Step2: Analyze electron - configuration of lithium

Lithium has 3 electrons. Its electron - configuration is 1s²2s¹. Gaining 3 electrons will give it 6 electrons (1s²2s²2p²), not a full outer shell.

Step3: Analyze electron - configuration of nitrogen

Nitrogen has 7 electrons. Its electron - configuration is 1s²2s²2p³. Gaining 3 electrons will give it 10 electrons (1s²2s²2p⁶), a full outer shell.

Step4: Analyze electron - configuration of argon

Argon has 18 electrons. Its electron - configuration is 1s²2s²2p⁶3s²3p⁶, already has a full outer shell and gaining 3 electrons will disrupt this stable state.

Answer:

Nitrogen