Question

name: teacher: uncommon
q2 chemistry: u3l3 atomic radius date: schools change
prepwork part 2: ionization energy
directions: read the passage below. as you read, annotate
the important information and vocabulary words. then
answer the questions.
**part 1: read & annotate:
ionization energy
ionization energy is the amount of energy required to remove an
electron from a gaseous atom or ion. this property is essential in
understanding how strongly an atom holds on to its electrons,
and it helps explain chemical reactivity.
trend across a period (left to right)
as you move from left to right across a period on the periodic
table, ionization energy increases. this is because the number of
protons in the nucleus increases, which raises the effective
nuclear charge (zeff). electrons are added to the same energy
level, so shielding remains relatively constant and the distance between the nucleus and the valence electron.
according to coulombs law, the force between opposite charges (like protons and electrons) increases as the
charges get stronger and the distance remains constant. therefore, valence electrons are more strongly attracted
to the nucleus, making them harder to remove, thus increasing the ionization energy.
trend down a group (top to bottom)
as you move down a group, ionization energy decreases. although more protons are added to the nucleus, new
energy levels are also added, increasing the distance between the nucleus and the outermost valence electrons.
this increases shielding, which reduces the pull on those valence electrons. according to coulombs law,
increasing the distance weakens the attraction between the nucleus and valence electrons, making it easier to
remove an electron, thus decreasing the ionization energy.
part 2: multiple choice questions

1. what is ionization energy?

a. energy needed to add an electron
b. energy needed to remove an electron
c. energy given off during bonding
d. mass of an atom

1. **what causes ionization energy to increase across a

period?**
a. more shielding
b. higher zeff
c. fewer electrons
d. larger atoms

1. why does ionization energy decrease down a group?

a. fewer protons
b. more electrons
c. increased shielding and distance
d. decreased atomic number

1. which atom has the lowest ionization energy?

a. he
b. cs
c. ne
d. f
part 3: true of false

1. ionization energy increases across a period. ____
2. larger atoms require more energy to remove an electron. ____
3. zeff has no effect on ionization energy. ____
4. shielding increases down a group. ____*
5. the closer an electron is to the nucleus, the more energy is required to remove it. ____

Explanation:

1. According to the text "Ionization energy is the amount of energy required to remove an electron from a gaseous atom or ion", option B is correct.
2. The text states "As you move from left to right across a period on the periodic table, ionization energy increases. This is because the number of protons in the nucleus increases, which raises the effective nuclear charge (Zeff)", so option B is correct.
3. The text mentions "As you move down a group, ionization energy decreases... This increases shielding... increasing the distance weakens the attraction between the nucleus and valence electrons", so option C is correct.
4. Cesium (Cs) is at the bottom of Group 1. As per the trend "ionization energy decreases down a group", Cs has the lowest ionization energy among the given options. So option B is correct.
5. The text clearly says "As you move from left to right across a period on the periodic table, ionization energy increases", so this statement is True.
6. Larger atoms (e.g., down - group elements) have lower ionization energy as electrons are farther and more shielded. So the statement "Larger atoms require more energy to remove an electron" is False.
7. The text shows that Zeff (effective nuclear charge) affects ionization energy (e.g., across - period trend). So the statement "Zeff has no effect on ionization energy" is False.
8. As you move down a group, new energy levels are added, and shielding increases. So the statement "Shielding increases down a group" is True.
9. The text (e.g., comparing Li and Na electrons) implies that closer electrons (less distance and less shielding) require more energy to remove. So the statement "The closer an electron is to the nucleus, the more energy is required to remove it" is True.

Answer:

1. B. Energy needed to remove an electron
2. B. Higher Zeff
3. C. Increased shielding and distance
4. B. Cs
5. True
6. False
7. False
8. True
9. True