Final answer:
Bromine is the largest atom. Chlorine has the highest ionization energy. Chlorine is the most electronegative. Electronegativity generally increases as you move across a period and decreases as you move down a group. Therefore, chlorine, which is located at the top of the group, is the most electronegative.
Step-by-step explanation:
Chlorine, selenium, and bromine are located near each other on the periodic table. To determine which of these elements is the largest atom, we look at their atomic radii. Atomic radius generally increases as you move down a group and decreases as you move across a period. Therefore, bromine, which is located at the bottom of the group, has the largest atom.
To determine which atom has the highest ionization energy, we look at the trend of ionization energy on the periodic table. Ionization energy generally increases as you move across a period and decreases as you move down a group. Therefore, chlorine, which is located at the top of the group, has the highest ionization energy. To determine which element is the most electronegative, we again look at the trend on the periodic table. Electronegativity generally increases as you move across a period and decreases as you move down a group. Therefore, chlorine, which is located at the top of the group, is the most electronegative.