G. Practice #2 – Periodic Trends
ATOMIC RADIUS
1. Does atomic radius increase or decrease as you go down a group/family on the periodic table?
increase
2. What causes this trend?
The larger number of shells (layers) causes the atom to become larger, similar to how putting on more layers of
clothes makes you appear larger
3. Does atomic radius increase or decrease as you go across a period/row on the periodic table?
decrease
4. What causes this trend?
As you go across a period, the number of shells remains the same, but the number of protons increase. The
increased number of protons pull the outer electrons with greater force, which causes the atom to shrink. The
nucleus acts like a stronger magnet and is able to pull the outer electrons with greater force.
5. A. Circle the atom in each pair that has the largest atomic radius.
Large = further away from He
a) Al
B
b) S
O
c) Br Cl
d) Na
Al
e) O
F
f) Mg Ca
B. Arrange the following groups of elements in order of increasing size.
a) In, Tl, Ga
b) Be, C, F
Tl, In, Ga
F, C, Be
IONS
6. Define an ion.
A charged atom (either positive or negative)
7. What is the difference between a cation and an anion?
Cation is a positive charged ion
Anion is a negative charged ion
8. Which is larger, Ca2+ or Ca and why?
Ca will be larger because there is a greater ratio of protons to electrons
Ca2+ will be smaller because there are less electrons, so the protons can pull like a stronger magnet
9. Which is larger, F-1 or F and why?
F-1, there are more electrons, so the positive nucleus has a harder time pulling in all the outer electrons
10. How does the ionic radius of a nonmetal compare with its atomic radius?
Not on test
IONIZATION ENERGY
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11. Define ionization energy.
The energy required to remove an electron from the outer shell (ring)
12. What trend in ionization energy do you see as you go down a group/family on the periodic table?
Decreases
13. What causes this trend?
Since there are more shells, the pull between the positive nucleus and the outer electrons is not at strong. Think of
the solar system. The planets that are further away have less gravitational pull than the ones that are closer
(Mercury has more of a pull to the sun than Neptune).
14. What trend in ionization energy do you see as you go across a period/row on the periodic table?
increases
15. What causes this trend?
The atom is getting closer to an octet. This means that atoms would prefer to gain electrons not lose them. Also,
since the atom is smaller, it would be harder to pull away one of the electrons from the outer shell
16. A. Circle the atom in each pair that has the greater ionization energy.
a) Li
d) Ca
Be
Ba
b) Na
e) P
K
Ar
c) Cl
f) Li
Si
K
B. Arrange the following groups of elements in order of increasing (smallest to largest) ionization energy.
a) Na, K, Li, Fr
b) P, Ar, Cl
Fr, K, Na, Li
P, Cl, Ar
ELECTRONEGATIVITY
17. Define electronegativity.
The ability of an atom to pull electrons to itself to form a chemical bond
18. What trend in electronegativity do you see as you go down a group/family on the periodic table?
decreases
19. What trend in electronegativity do you see as you go across a period/row on the periodic table?
increases
20. Which element has the greatest electronegativity? _____________________
Fluorine
21. A. Circle the atom in each pair that has the greater electronegativity.
a) Ca
d) Br
Ga
As
b) Li
e) Ba
O
Sr
c) Cl
f) O
S
S
B. Arrange the following groups of elements in order of decreasing (largest to smallest) electronegativity.
a) C, Ge, Si
b) Be, C, F
C, Si, Ge
F, C, Be
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H. Review
____9. Which of the following atoms has the largest atomic radius?
A) Na
B) K
C) Mg
D) Ca
____10. Which noble gas has the highest first ionization energy?
A) radon
C) neon
B) krypton
D) helium
____11. Which sequence of elements is arranged in order of decreasing atomic radii?
A) Al, Si, P
C) Cl, Br, I
B) Li, Na, K
D) N, C, B
____12. Which list of elements from Group 2 on the Periodic Table is arranged in order of increasing atomic radius?
A) Be, Mg, Ca
C) Ba, Ra, Sr
B) Ca, Mg, Be
D) Sr, Ra, Ba
____13. As each successive element in Group 15 of the Periodic Table is considered (going from top to bottom) in order of
increasing atomic number, the atomic radius
A) decreases
B) increases
C) remains the same
____14. The strength of an atom’s attraction for the electrons in a chemical bond is the atom’s
A) electronegativity
C) heat of reaction
B) ionization energy
D) heat of formation
____15. Which properties are most common in nonmetals?
A) low ionization energy and low electronegativity
B) low ionization energy and high electronegativity
C) high ionization energy and low electronegativity
D) high ionization energy and high electronegativity
____16. Which Group 17 element has the least attraction for electrons?
A) F
B) Cl
C) Br
D) I
____17. Which element in Group 16 has the greatest tendency to gain electrons?
A) Te
B) Se
C) S
D) O
____18. The Group 17 element with the highest electronegativity is
A) fluorine
C) bromine
B) chlorine
D) iodine
19. As the elements of Group 1 on the Periodic Table are considered in order of increasing atomic radius, the ionization
energy of each successive element generally
A) decreases
B) increases
C) remains the same
____20. The amount of energy required to remove the outermost electron from a gaseous atom in the ground state is
known as
A) first ionization energy
C) conductivity
B) activation energy
D) electronegativity
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____22. Which of the following Group 2 elements has the lowest first ionization energy?
A) Be
B) Mg
C) Ca
D) Ba
____23. As elements of Group 1 of the Periodic Table are considered in order from top to bottom, the ionization energy of
each successive element decreases. This decrease is due to
A) decreasing radius and decreasing shielding effect
B) decreasing radius and increasing shielding effect
C) increasing radius and decreasing shielding effect
D) increasing radius and increasing shielding effect
____24. Which sequence correctly places the elements in order of increasing ionization energy?
A) H → Li → Na → K
C)O → S → Se → Te
B) I → Br → Cl → F
D)H → Be → Al → Ga
____25. Compared to the atomic radius of a sodium atom, the atomic radius of a magnesium atom is smaller. The smaller
radius is primarily a result of the magnesium atom having
A) a larger nuclear charge (more protons)
B) a smaller nuclear charge
C) more principal energy levels D) fewer principal energy levels
____26. Which of these elements has the least attraction for electrons in a chemical bond?
A) oxygen
B) fluorine
C) nitrogen
D) chlorine
____27. The ability of carbon to attract electrons is
A) greater than that of nitrogen, but less than that of oxygen
B) less than that of nitrogen, but greater than that of oxygen
C) greater than that of nitrogen and oxygen
D) less than that of nitrogen and oxygen
____28. As the elements Li to F in Period 2 of the Periodic Table are considered in succession, how do the relative
electronegativity and the covalent radius of each successive element compare?
A) The relative electronegativity decreases, and the atomic radius decreases.
B) The relative electronegativity decreases, and the atomic radius increases.
C) The relative electronegativity increases, and the atomic radius decreases.
D) The relative electronegativity increases, and the atomic radius increases.
H. Review Periodic table and Periodic trends
2. Why does atomic radius increase as you go down a group?
The increased number of shells makes the atom larger, similar to how extra layers of clothes makes a person appear larger
3.Which trend(s) can be described using the following diagram?
a. ionization energy
b. electronegativity
c. atomic radius
d. periodicity
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4.Which trend(s) can be described using the following diagram?
a. ionization energy
b. electronegativity
c. atomic radius
d. periodicity
H. Review Questions
16. Arrange the following to increasing electronegativity : Te, Sn, Rb, Xe, In
(nobles gases are very low electronegativity) Xe, Rb, In, Sn, Te (largest)
17. Arrange the following to decreasing electronegativity: Cs, Li, Fr, Na, H
H, Li, Na, Cs, Fr (smallest)
18. Using the term octet, explain why electronegativity increasing from left to right on a period of the periodic table.
As you go across a period, the atom gets closer to an octet. Atoms want stability and an octet gives stability, so
atoms are going to get increasingly desperate to achieve an octet as you get closer to 8 valence electrons.
19. Arrange the following to decreasing ionization energy : N, Bi, As, Sb, P
N, P, As, Sb, Bi (smallest)
20. Arrange the following to increasing ionization energy : N, C, B, Li, O, Ne, F
Li, B, C, N, O, F, Ne (largest)
21. Using the term shells, explain why ionization energy decreases as you go down a group on the periodic table.
Since there are more shells, the pull between the positive nucleus and the outer electrons is not at strong. Think of
the solar system. The planets that are further away have less gravitational pull than the ones that are closer
(Mercury has more of a pull to the sun than Neptune).
22. Arrange the following to increasing atomic radii : Na, Mg, Al, Ar, Si, P, S, Cl
Ar, Cl, S, P, Si, Al, Mg, Na (largest)
23. Arrange the following to decreasing atomic radii: Mg, Ba, Ca, Be, Sr, Ra
Ra, Ba, Sr, Ca, Mg, Be (smallest)
24. Using number of protons and electrons in your argument, explain why atomic radii decreases as you go from left to right
on the same period of the periodic table.
As you go across a period, the number of shells remains the same, but the number of protons increase. The
increased number of protons pull the outer electrons with greater force, which causes the atom to shrink. The
nucleus acts like a stronger magnet and is able to pull the outer electrons with greater force.
25. What does the term "octet" mean and why do elements want an octet?
Octet means that an atom has 8 valence electrons (8 electrons in the outer shell). Atoms want to obtain an octet
because it makes them stable. One exception to this would be Hydrogen and Helium, which want to obtain a duet
(2 electrons) to obtain stability
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26. Draw and label the trends for atomic radius, ionization energy, and electronegativity below
Decreasing
Increasing
Atomic radius
Increasing
Increasing
Decreasing
Decreasing
Ionization energy
Electronegativity
For the test, you should be able to: define or identify the terms related to this unit, explain the periodic trends of
groups and periods, arrange elements using a specific trend.
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