Question

question 24 (1 point)
how does atomic radius change from left to right across a period in the periodic table?
o a it first increases, then decreases.
o b it first decreases, then increases.
o c it tends to increase.
o d it tends to decrease.

question 25 (2 points)
what causes the shielding effect to remain constant across a period?
o a the charge on the nucleus is constant.
o b the atomic radius increases.
o c electrons are added to the same principal energy level.
o d electrons are added to different principal energy levels.

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

Explanation:

• Question 24: As we move from left to right across a period, the number of protons in the nucleus increases (nuclear charge increases), and electrons are added to the same principal energy level. The increased nuclear charge pulls the electrons closer, so the atomic radius tends to decrease.
• Question 25: Shielding effect depends on the number of inner - shell electrons. When electrons are added to the same principal energy level (across a period), the number of inner - shell electrons (which cause shielding) remains the same. So, the shielding effect remains constant because electrons are added to the same principal energy level.
• Question 26: Similar to the reasoning in Question 24, as we move from left to right across a period, due to increasing nuclear charge and electrons in the same shell, the atomic size (radius) decreases.

Answer:

• Question 24: d. It tends to decrease.
• Question 25: c. Electrons are added to the same principal energy level.
• Question 26: c. decreases as you move from left to right across a period.