Which of the following arrangement of elements is in decreasing order of electronegativity?

Analyze the question: We need the arrangement in which electronegativity goes from highest to lowest.

Concept: Na, Mg, Al, Si and P are all in Period 3. Across a period from left to right, nuclear charge increases while the electrons are added to the same shell. The atomic radius decreases, so the nucleus attracts bonding electrons more strongly. This means electronegativity increases from left to right across a period.

Order of the elements in Period 3: Na, Mg, Al, Si, P.

So electronegativity increases in this order: Na < Mg < Al < Si < P

Pauling values for checking:

• Na = 0.93
• Mg = 1.31
• Al = 1.61
• Si = 1.90
• P = 2.19

Decreasing order means we reverse the list: P > Si > Al > Mg > Na

Checking the options:

• A. Na, Mg, Al, Si, P: this is increasing order, so it is wrong.
• B. Na, Al, Mg, P, Si: this is jumbled, so it is wrong.
• C. P, Mg, Na, Si, Al: this is jumbled, so it is wrong.
• D. P, Si, Al, Mg, Na: this is the correct decreasing order.

Tip: For Period 3 questions, remember that electronegativity, ionization energy and non-metallic character all increase from left to right. Atomic radius and metallic character decrease. If a question asks for decreasing electronegativity in a period, simply read the period backwards, from the right-hand element to the left-hand one.