Question

question 26 (1 point)
atomic size generally
a increases as you move from left to right across a period.
b remains constant within a period.
c decreases as you move from left to right across a period.
d decreases as you move from top to bottom within a group.

question 27 (1 point)
what element in the second period has the largest atomic radius?
a carbon
b neon
c lithium
d potassium

question 28 (1 point)
which of the following factors contributes to the increase in atomic size within a group in the periodic table as the atomic number increases?
a fewer electrons in the highest occupied energy level
b more shielding of the electrons in the highest occupied energy level
c an increase in size of the nucleus
d an increase in number of protons

Explanation:

• Question 26: As you move from left to right across a period, the atomic size decreases. This is because the number of protons increases (higher nuclear charge), pulling the electrons closer. Moving down a group, atomic size increases due to more electron shells.
• Question 27: In the second period, lithium (\(Li\)) has the largest atomic radius. As we move from left (lithium) to right (neon) in the period, atomic radius decreases. Carbon (\(C\)) is to the right of lithium, neon (\(Ne\)) is the noble gas (far right), and potassium (\(K\)) is in the fourth period.
• Question 28: As atomic number increases within a group, there are more electron shells. The inner - shell electrons shield the outer - shell electrons from the nuclear charge (more shielding), allowing the outer electrons to be further from the nucleus, increasing atomic size. Fewer electrons in the highest occupied energy level is incorrect (electrons increase down a group). An increase in nucleus size or proton number (which also occurs) is counteracted by shielding, and these factors do not contribute to the increase in atomic size as much as shielding.

Answer:

• Question 26: C. decreases as you move from left to right across a period.
• Question 27: C. lithium.
• Question 28: B. more shielding of the electrons in the highest occupied energy level.