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Homework-24
Pages: 132-134
(4.3.1) Periodic Trends-Ionization Energy
Elemental, My Dear Watson
The famous detective Sherlock Holmes used many kinds of clues to solve his cases. Like
any good detective, he knew the value of fingerprints because no two people have the
same fingerprints. In a way, atomic numbers are similar to fingerprints, because no two
elements have the same atomic number. In this activity, you will take on the role of a
chemical detective who tracks down elements by deducing their atomic numbers. Use the
periodic table on the inside back cover of your textbook to help you.
1. The atomic number of element X is 6 less than the atomic number of element W. Element W
is one of the elements that make up water. What are elements X and W?
___________________________________________
2. To find element Z, start at the beginning of Period 2 on the periodic table. Move to the right
until you come to an element whose atomic number is 6 more than the atomic number of the
first element in the period. What is element Z? ________________________________
3. Element D loses two electrons in a chemical reaction. Now it has the same number of
electrons as Neon. What is element D? ________________________
4. If the atomic numbers of Calcium and Beryllium are added together, you will get the atomic
number of this element. What is the element? ________________________
5. Element Q has an atomic number that is less than that of iron and five times that of an element
in Group 13. What is element Q? What is its atomic number? _____________________
6. This metal element has an atomic number that some people think is unlucky. What is the
element? What did you guess as its atomic number?
_______________________________________________________________
7. Add together the atomic numbers of the first three noble gases, and you will have the atomic
number of this element. What is the element? ________________________
8. The atomic number of element J is greater than the atomic number of platinum but less than
the atomic number of lead. Its atomic number is divisible by 4. What is element J?
________________________________________
9. List four kinds of information that you can find on the periodic table.
______________________________________________________________________________
______________________________________________________________________________
____________________________
10. Explain why ionization energies tend to decrease down a group.
_________________________________________
_________________________________________________________________________________
_______________
Lesson-25
Pages: 135-136
(4.3.2) Atomic Radius
REVIEW of Lesson-24 (Periodic Trends - Ionization Energy)
1. Periodic trends are related to the atomic structure of the elements.
2. Ionization energy increase as you move across a period and decrease as you move down a group.
INTRODUCTION
In this lesson you will learn how to describe periodic trends in atomic radius.
VOCABULARY
atomic radius
bond radius
ionic size
DO NOW (Answer the following questions by using your textbook)
1. Why is measuring the size of an atom difficult? _________________________________________________
__________________________________________________________________________________________
2. Which metal has the larger radius, Li or Na? Why? ______________________________________________
_________________________________________________________________________________________
Practice Questions
1. One method of measuring the size of an atom involves calculating a value that is _____ the distance between
the nuclei of two bonded atoms.
a. twice
b. half
c. equal to
d. one-quarter
2. Across a period in the periodic table, atomic radii generally
a. decrease.
b. decrease, then increase.
c. increase.
d. increase, then decreas
3. Down a group in the periodic table, atomic radii generally
a. decrease.
b. remain constant.
c. increase.
d. vary unpredictably.
4. For the alkaline-earth metals, atoms with the smallest radii have the
a. largest atomic numbers.
c. most mass.
b. greatest volumes.
d. highest ionization energies.
5. As the atomic number of the metals of Group 1 increases, the ionic radius
a. increases.
b. decreases.
c. remains the same.
d. cannot be determined
6. An element with the smallest anionic (negative-ionic) radius would be found in of the periodic table.
a. Group 1, Period 7
b. Group 3, Period 4
c. Group 5, Period 3
d. Group 17, Period 2
7. Which of the following elements has the largest atomic radius?
a. Boron
b. Aluminum
c. Gallium
d. Indium
8. Going down a group in the periodic table, electron shielding generally causes the effective nuclear charge to
a. increase.
b. decrease.
c. remain the same.
d. vary unpredictably
9. Going across a period in the periodic table, electron shielding generally has little effect. As a result, the
effective nuclear charge
a. increases.
b. decreases.
c. remain the same.
d. varies
unpredictably.
10. Trends in the periodic table indicate that an element in which of the following periods and groups will
have the smallest anion (negative ion) radius?
a. Period 2, Group 1
b. Period 4, Group 16
c. Period 7, Group 2
d. Period 1, Group 1
Homework-25
Pages: 135-136
(4.3.2) Atomic Radius
Directions: Use the periodic table below to answer the following questions.
1. Which letter represents the metals on the periodic table? ______________________________
2. Which letter represents the noble gases on the periodic table? __________________________
3. Which letter represents a period on the periodic table? ________________________________
4. Which letter represents the nonmetals on the periodic table? ___________________________
5. Which letter represents a group on the periodic table? ________________________________
6. Which is the best reason that the atomic radius generally increases with atomic number in each
group of elements?
a. The nuclear charge increases.
b. The number of neutrons increases.
c. The number of energy levels increases.
d. A new octet forms.
7. When determining the size of an atom by measuring the bond radius, the radius of an atom is
a. equal to the distance between nuclei.
b. one-half the distance between
nuclei.
c. twice the distance between nuclei.
d. one-fourth the distance between
nuclei.
8. Explain the large decrease in atomic radii as you move across a period from Group 1 to Group
14.
______________________________________________________________________________
______________
______________________________________________________________________________
______________
9. Explain how electron shielding affects the general trend in radii of atoms of elements going
from left to right across a period in the periodic table.
______________________________________________________________
______________________________________________________________________________
______________
______________________________________________________________________________
______________
Lesson-26
Pages: 137-141
(4.3.3) Electronegativity & Other Trends
REVIEW of Lesson-25 (Atomic Radius)
1. Atomic radius increases as you move down a group and decrease as you move across a period.
INTRODUCTION
In this lesson you will learn how to describe periodic trends in electronegativity, melting point and boiling point
VOCABULARY
electronegativity
DO NOW (Answer the following questions by using your textbook)
1. What can you tell about an atom that has high electronegativity? ____________________________________
__________________________________________________________________________________________
2. What periodic trends exist for electronegativity? ________________________________________________
__________________________________________________________________________________________
Practice Questions
Directions: Use the correct term(s) below to complete the following sentences.
energy
electron shielding
electronegativity
1. The removal of an electron from a neutral atom, A, can be described as:
A + ionization ____________________  A+ + e-
energy
2. The effect that causes the outermost electrons in an atom or ion to be held less tightly to the nucleus because
inner electrons is called ____________________.
3. A measure of the ability of an atom in a chemical compound to attract electrons is called
___________________________.
4. A neutral atom’s electron affinity is defined as its change in ____________________ as it gains an electron.
5. Electron affinity tends to
a. decrease across a period and decrease down a group.
b. increase across a period and increase down a group.
c. decrease across a period and increase down a group.
d. increase across a period and decrease down a group.
6. An element with the lowest electronegativity would be found in of the periodic table.
a. Group 1, Period 7
b. Group 3, Period 4
c. Group 5, Period 3
d. Group 17, Period 2
7. Refer to a periodic table and determine which element has the lowest electron affinity.
a. Cl
b. Se
c. Cs
d. Te
8. Which of the following elements has the largest electronegativity?
a. lithium
b. carbon
c. chlorine
Homework-26
Pages: 137-141
d. iodine
(4.3.3) Electronegativity & Other Trends
Directions: Complete the sentences below by using the vocabulary list.
electronegativity
ionization energy
electron shielding
electron affinity
bond radius
1. The amount of energy needed to remove an electron from a specific atom is called
the _________________________energy of the atom.
2. The ______________________ is half the distance from center to center of two
like atoms bonded together.
3. _____________________is the energy change that occurs when a neutral atom
gains an electron.
4. _____________________is a numerical value that reflects how much an atom in a molecule
attracts electrons.
5. The effect that causes the outermost electrons in an atom or ion to be held less tightly to the
nucleus because of inner electrons is called ____________________.
6. In each pair circle the larger ion.
a. Ca+2, Mg+2
b. Cl-, P-3
c. Cu+, Cu+2
7. Complete the following table.
8. Arrange the following elements in order of increasing electron affinity: Cl, Se, S, Cs, and Te.
______________________________________________________________________________
______________
9. Arrange the following anions (negative ions) in order of increasing ionic radius: Cl–-, F–, Se2–,
and Te2–
______________________________________________________________________________
______________
10. Arrange the following cations (positive ions) in order of increasing ionic radius: Be2+, K+,
Mg2+, and Rb+.
______________________________________________________________________________
______________
11. What is electron shielding?
______________________________________________________________________
______________________________________________________________________________
______________