Question

select the correct answer.
consider the group 1a element sodium (atomic number 11), the group 3a element aluminum (atomic number 13), and the group 7a element chlorine (atomic number 17). these elements are in period 3. how are the first ionization energies of these elements related?
a. sodium > aluminum > chlorine
b. sodium < aluminum < chlorine
c. sodium < chlorine < aluminum
d. sodium > chlorine > aluminum

Explanation:

Step1: Understand ionization energy trend

Ionization energy increases across a period from left to right in the periodic table.

Step2: Locate elements in period 3

Sodium (Na) is on the left, aluminum (Al) is in the middle, and chlorine (Cl) is on the right in period 3.

Step3: Apply the trend

Since ionization energy increases left - to - right, sodium has the lowest first ionization energy, followed by aluminum, and chlorine has the highest. So, sodium < aluminum < chlorine.

Answer:

B. sodium < aluminum < chlorine