Question

question 48 (1 point)
which of the following factors contributes to the increase in ionization energy from left to right across a period?
o a fewer electrons in the highest occupied energy level
b an increase in the size of the nucleus
o c an increase in the shielding effect
d an increase in the number of protons

question 49 (1 point)
as you move from left to right across the second period of the periodic table
a atomic mass decreases.
b ionization energy increases.
o c electronegativity decreases.
d atomic radii increase.

question 50 (1 point)
of the following elements, which one has the smallest first ionization energy?
a aluminum
b silicon
o c boron
d carbon

Explanation:

• Question 48:
• As we move from left to right across a period, the number of protons in the nucleus increases. This leads to a greater positive charge in the nucleus, which attracts the electrons more strongly. As a result, more energy is required to remove an electron (ionization energy increases).
• Option a: The number of electrons in the highest - occupied energy level increases across a period (not fewer).
• Option b: The size of the nucleus (in terms of radius) does not increase significantly in a way that would directly cause an increase in ionization energy across a period. The main factor is the increase in the number of protons (nuclear charge).
• Option c: The shielding effect (due to inner - shell electrons) remains relatively constant across a period (since the number of inner - shell electrons does not change).
• Question 49:
• Option a: Atomic mass generally increases from left to right across a period as the number of protons and neutrons increases.
• Option b: Ionization energy increases from left to right across a period because of the increasing nuclear charge (more protons) which holds the electrons more tightly.
• Option c: Electronegativity increases from left to right across a period (not decreases).
• Option d: Atomic radii decrease from left to right across a period due to the increasing nuclear charge pulling the electrons closer.
• Question 50:
• Ionization energy generally increases from left to right across a period.
• Boron (B), carbon (C), silicon (Si), and aluminum (Al) are in the following order in the periodic table: Boron (period 2, group 13), carbon (period 2, group 14), aluminum (period 3, group 13), silicon (period 3, group 14).
• Aluminum has a lower ionization energy than silicon (since it is to the left of silicon in the same period). Boron has a higher ionization energy than aluminum because, although boron is in a higher energy level (n = 2 for B, n = 3 for Al), the effect of the increasing nuclear charge in the same group (from Al to B, but B is in a higher period) is less significant than the period - related trend. Carbon has a higher ionization energy than boron (as it is to the right of boron in the same period).

Answer:

• Question 48: d. an increase in the number of protons
• Question 49: b. ionization energy increases
• Question 50: a. aluminum