Question

instructions: in each question, identify the element with the greatest ionization energy:

1. chlorine (cl), sulfur (s), sodium (na), silicon (si)
2. aluminum (al), indium (in), boron (b), gallium (ga)
3. calcium (ca), iron (fe), cobalt (co), copper (cu)

Explanation:

Step1: Recall ionization energy trend

Ionization energy increases across a period (left - to - right) and decreases down a group in the periodic table.

Step2: Analyze first set

For Chlorine (Cl), Sulfur (S), Sodium (Na), Silicon (Si):

• They are in the same period (Period 3).
• Order from left - to - right: Na (Group 1), Si (Group 14), S (Group 16), Cl (Group 17).
• As per the trend, Cl has the highest ionization energy among them.

Step3: Analyze second set

For Aluminum (Al), Indium (In), Boron (B), Gallium (Ga):

• B is in Period 2, Al in Period 3, Ga in Period 4, In in Period 5.
• Since ionization energy decreases down a group and B is highest up in the group (Group 13), B has the highest ionization energy.

Step4: Analyze third set

For Calcium (Ca), Iron (Fe), Cobalt (Co), Copper (Cu):

• Ca is in Group 2, Fe (Group 8), Co (Group 9), Cu (Group 11).
• In the same period (Period 4), as we move from left (Ca) to right (Cu), ionization energy generally increases.
• Cu has the highest ionization energy among them as it is further to the right in the period.

Answer:

1. Chlorine (Cl)
2. Boron (B)
3. Copper (Cu)