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Find the valency of an element


Amir was asked to find valency of the element whose atomic number was 15.
Below are his steps:
Step 1: The electronic configuration is 2, 8, 5.
Step 2: It has 5 valence electrons.
Step 3: To attain a complete octet, atom needs to lose 5 electrons, so its valency is 5.
Where did he go wrong and why?
Choose 1 answer: