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Question:

Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the periodic table. Write the electronic configuration of these two elements. Which of these will be more electronegative and why?

Solution:

Nitrogen (N) has an atomic number of 7, meaning it has 7 electrons. Its electronic configuration is 1s²2s²2p³.

Phosphorus (P) has an atomic number of 15, meaning it has 15 electrons. Its electronic configuration is 1s²2s²2p⁶3s²3p³.

Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond. Electronegativity generally increases across a period (from left to right) and decreases down a group (from top to bottom) in the periodic table.

Both nitrogen and phosphorus are in group 15, but nitrogen is higher up in the group. As electronegativity decreases down a group, nitrogen will be more electronegative than phosphorus. Nitrogen's smaller atomic size and closer proximity of its valence electrons to the nucleus result in a stronger attraction for shared electrons in a bond compared to phosphorus.