Question

question 32 (1 point)
which of the following elements has the smallest first ionization energy?
o a calcium
o b sodium
o c potassium
o d magnesium

question 33 (1 point)
compared with the electronegativities of the elements on the left side of a period, the electronegativities of the elements on the right side of the same
period tend to be
o a the same
o b higher
o c lower
o d unpredictable

question 34 (1 point)
as you move from left to right across the second period of the periodic table
o a ionization energy increases.
o b electronegativity decreases.
o c atomic radii increase.
o d atomic mass decreases.

Explanation:

Question 32

Ionization energy decreases down a group (due to increased atomic radius and shielding) and generally increases across a period. Calcium (Ca) and magnesium (Mg) are in Group 2, sodium (Na) and potassium (K) are in Group 1. Potassium is below sodium in Group 1, so it has a larger atomic radius. Larger atomic radius means less attraction between the nucleus and the outermost electron, so it is easier to remove (lower ionization energy). Among the given elements, potassium has the largest atomic radius (as it is in the fourth period while sodium is in the third, calcium in the fourth but in Group 2 which has higher ionization energy than Group 1 in the same period, magnesium in the third).

Electronegativity is the ability of an atom to attract electrons in a chemical bond. As we move from left to right across a period, the nuclear charge increases (number of protons increases) and the atomic radius decreases. This leads to a greater ability to attract electrons, so electronegativity increases.

• Ionization energy: As we move from left to right across a period (e.g., the second period), the nuclear charge increases, and the atomic radius decreases. The outermost electrons are more tightly held, so ionization energy increases.
• Electronegativity: Increases across a period (as explained in Question 33).
• Atomic radii: Decreases across a period because of increased nuclear charge pulling electrons closer.
• Atomic mass: Generally increases across a period as we go from lighter elements (e.g., lithium) to heavier elements (e.g., neon) in the second period.

Answer:

c. potassium

Question 33