Chapter 5 – The Periodic Law
5-1 History of the Periodic Table
A. – Mendeleev and Chemical Periodicity
1. Dmitri Mendeleev went about organizing the elements according to their _______________________ as
you might organize information for a _____________________ ________________. He placed the name
of each known element on a ______________, together with the atomic _____________ of the element and
a list of its observed _______________________ and _______________________ properties. He then
arranged them according to various properties and looked for _________________ or
________________________.
2. Mendeleev noticed that when the elements were arranged in order of _______________________ atomic
________________, certain similarities in their chemical properties appeared at _____________________
intervals. Such a repeating pattern is referred to as ________________________.
3. His first periodic table was published in ___________.
a. He placed _________________, __ (atomic mass _________), after ____________________, ___
(atomic mass _________). It allowed him to place _______________________ in a group of
elements with which it shares similar ___________________________.
b. Mendeleev’s procedure left several ______________ ______________ in his periodic table. He
boldly ______________________ the existence and properties of the elements that would fill
_________________ of the spaces. Today these elements are known as ____________________,
_______________________, and _________________________. Their properties are
___________________________ ________________________ to those predicted by Mendeleev.
B. – Moselely and the Periodic Law
1. In 1911, Henry Moseley examined the _________________ of 38 different metals. He discovered a
previously unrecognized ______________________ - The elements in the periodic table were arranged in
increasing order according to _____________________ _____________________, or the number of
_________________________ in the __________________________.
2. Moseley’s work led to both the modern definition of _____________________ ______________________
and the recognition that ______________________ ________________________, not ______________
__________________, is the basis for the organization of the periodic table
3. Today, Mendeleev’s principle of chemical __________________________ is correctly stated in what is
known as the periodic law :
The physical and chemical properties of the elements are ________________________
functions of their _____________________ _________________________
C. – The Modern Periodic Table
The Noble Gases
1. The periodic table is an arrangement of the elements in order of their _________________
_____________________ so that elements with similar properties fall in the same ___________________,
or _____________________.
2. In 1894 scientists discovered ________________, _____, a gas in the atmosphere that had previously
___________________ _______________ because of its total lack of chemical ____________________.
In 1868 another noble gas, __________________, _____, had been discovered as a component of the
____________, based on the emission ___________________ of __________________________.
3. Ramsay proposed a new group which he placed between the groups now known as Group _____ (the
____________________ family) and Group _______ (the _________________ family).
4. In 1898 the noble gases __________________, _____, and ___________________, ____, were added to
the new group. The final noble gas, ___________________, _____, was discovered in 1900.
The Lanthanides
5. In the early 1900’s the _______________________ chemistry of the lanthanides was finally understood.
6. The lanthanides are the _______ elements with atomic numbers from _____ (_________________, ____)
to ________ (_______________________, ____).
7. Because these elements were so _________________________ in chemical and physical properties, the
process of __________________________ and _________________________ them was a tedious task.
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The Actinides
8. The actinides are the _______ elements with atomic numbers _______ (___________________, _____) to
__________ (___________________________, ______).
9. The lanthanides and actinides belong in Periods _____ and ______, respectively, between Groups _____
and _______. To save _______________, they are usually set off ________________ the main portion of
the periodic table.
Periodicity
10. Periodicity with respect to atomic ___________________ can be observed in any __________________ of
elements in the periodic table.
11. The differences in atomic number between Group ____ metals follows the same _____________________
as the differences in atomic number between the _______________ ______________.
12. The reason for __________________________ is explained by the arrangement of ___________________
around the nucleus.
5-2 Electron Configuration and the Periodic Table
A. – Intro
1. The Group ______ elements of the periodic table (the ______________ ____________) undergo few
___________________________ ______________________. This stability results from the gases special
electron ___________________________.
2. Generally, the electron configuration of an atom’s ______________________ _______________________
energy level governs the atom’s __________________________ ______________________________.
B. - Periods and Blocks of the Periodic Table
1. Elements are arranged vertically in the periodic table in ___________________ that share similar chemical
_____________________________. They are also organized in ____________________________ rows,
or periods . There are a total of _______________ periods in the modern periodic table.
Instructor’s Note: The book spends a lot of time in this section on the relation between electron configuration
and the “blocks” in the periodic table. Since this concept was used to teach you electron configuration in
Chapter 4, it will be assumed that you understand the concept and it will be skipped in this reading guide.
The s-Block Elements: Groups 1 and 2
2. The elements of the s-block are chemically _________________________ __________________.
3. The elements of Group 1 of the periodic table are called the __________________ __________________.
a. They are so reactive that they are not found in ___________________ as ___________ elements
b. They combine vigorously with most _________________________, and they react strongly with
___________________ to produce _________________________ gas.
4. The elements of Group 2 of the periodic table are called the ____________________-_______________
metals.
a. They are ___________ reactive than the alkali metals, and are also too reactive to be found in
_______________________ as _________________ elements.
Hydrogen and Helium
5. Hydrogen does not share the same ___________________________ as the elements of Group _______. It
is a ___________________ element, with properties that do not closely _____________________ those of
any group.
6. Because helium’s highest occupied energy levelis __________________ by ________ electrons, it
possesses special chemical _______________________, exhibiting the unreactive nature of a Group
______ element.
The d-Block Elements: Groups 3-12
7. The d-block elements are ________________ with typical ___________________ properties and are often
referred to as ____________________________ elements.
a. They are typically ___________ _____________________ than alkali metals and alkaline-earth
metals.
b. Palladium, __________________________ and _____________ are among the least reactive of all
elements.
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The p-Block Elements: Groups 13 - 18
8. The p-block elements together with the s-block elements are called the ______________
_______________ elements.
9. The properties of elements of the p-block ____________ __________________. At its right hand end, it
includes all of the _____________________ except hydrogen and helium. All ________ of the
__________________________ are also in the p-block. There are _____________ p-block metals.
10. The elements of Group ______ are known as the
halogens . They are the most ____________________
nonmetals.
The f-block Elements: Lanthanides and Actinides
11. There are a total of ________ f-block elements between lanthanum and hafnium. There are also _______
f-block elements, the _____________________, between actinium and element __________.
12. The actinides are all ________________________________. The first ___________ actinides have been
found ____________________________ on Earth. The remaining actinides are known only as
____________________________-made elements.
5-3 Electron Configuration and Periodic Properties
A. – Atomic Radii
1. Atomic radius may be defined as _______-__________ the distance between the ______________ of
identical atoms that are bonded together.
2. The trend to _______________________ atoms across a period is caused by the increasing
_______________________ charge of the nucleus.
3. As electrons occupy sublevels in successively higher main energy levels located _____________________
from the nucleus, the sizes of the atoms ___________________________. In general, the atomic radii of
the _____________-group elements ______________________ down in a group.
B. – Ionization Energy
1. An electron can be _____________________ from an atom if enough ____________________ is supplied.
Write the equation for ionization:
_______ + _________________
_________
+ _________
The ______ represents an ______ of element A with a ______________ positive charge.
a. An ion is an atom or group of ________________ atoms that has a _____________________ or
_________________________ charge.
2. Any process that results in the ____________________ of an ________ is referred to as
ionization .
3. Ionization energy (or ____________ ionization energy) is the energy required to ____________________
one electron from a ____________________ atom. Measurements of ionization energies are made on
_________________________ atoms in the ________ phase.
Write the equation for the first ionization of sodium (at #11), using the ionization energy from the table on
page 143:
_______ + _________________
_________
+ _________
Period Trends
4. Group ____ metals have the _________________ first ionization energies in their respective periods. This
is a major reason for the ____________ _________________________ of this group.
5. Group ____ elements, the _______________ ___________, have the __________________ ionization
energies. They do not lose electrons _________________.
6. In general, ionization energies of the __________-group elements ______________________ across each
period
a. The increase is caused by ________________________ nuclear charge (and smaller radius)
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Group Trends
7. Among the main-group elements, ionization energies generally _________________________ down the
groups.
a. Electrons removed from atoms of each succeeding element in a group are in higher energy levels
___________________ from the nucleus
b. As atomic number increases going down a group, more _______________________ lie between
the nucleus and electrons in the highest occupied energy levels. This partially ________________
the ____________________ electrons from the effect of the nuclear ____________________.
Removing Electrons from Positive Ions
8. The energies for removal of _____________________________ electrons from an atom are referred to as
the ___________________ ionization energy, ____________________ ionization energy, and so on.
9. Each _______________________ electron removed from an ion feels an increasingly _________________
effective nuclear __________________________ (the nuclear ___________________ minus the electron
___________________________).
10. Large jumps in ionization energy occur when an ion assumes a _____________-gas configuration.
Write the equations for the first, second and third ionizations of Magnesium (at# 12), using ionization
energies from Table 5-3 on page 145.
_______ + _________________
_________
+ _________
_______ + _________________
_________
+ _________
_______ + _________________
_________
+ _________
Explain why there is such a great increase in ionization energy between the removal of the second and third
electron in magnesium:
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
C. – Electron Affinity
1. Electron affinity is the __________________ change that occurs when an electron is
___________________ by a neutral atom.
2. Most atoms _______________________ energy when they acquire an electron:
_______ + _________
_________
+ _____________________
The quantity of energy released is represented by a ___________________ number.
3. Some atoms must be “_________________” to gain an electron by the addition of energy:
_______ + _________ + _____________________
_________
The quantity of energy absorbed is represented by a ___________________ number. An ion produced in
this way will be ________________________ and will ____________ the added electron spontaneously.
4. The _______________________ (Group _____) gain electrons most ________________________.
5. Ignore the text at this point, and look at the table on page 147 to answer the following two questions:
a. IN GENERAL, as you go across a period, electron affinity tends to ________________________,
except for irregularities due to the stability of _______________-filled and
______________________-filled sublevels
b. IN GENERAL, as you go down in a group of main-group element, electron affinity tends to
________________________
6. It is always more __________________________ to add a second electron to an already
_______________________ charged ion. Therefore second electron affinities are all _________________.
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D. – Ionic Radii
1. A cation is a __________________________ ion. The formation of a cation by the ___________ of one or
more _________________________ always leads to a __________________________ in atomic radius.
2. An anion is a ________________________ ion. The formation of an anion by the addition of one or more
_________________________ always leads to an __________________________ in atomic radius.
3. Within each period of the periodic table, the ________________ at the left tend to form ________________
and the __________________________ at the upper right tend to form ____________________________.
Period Trends
4. Cationic radii _____________________ across a period because the electron cloud
____________________ due to the increasing ________________________ charge acting on the
electrons.
5. Anionic radii ________________________ across each period for the elements in Groups ____-______.
Group Trends
6. Just as there is a gradual _____________________ of atomic radii down a group, there is also a gradual
__________________________ of ionic radii.
E. - Valence Electrons
1. Chemical compounds form because electrons are ____________, ______________, or _______________
between atoms. The electrons that interact in this manner are those in the _______________________
energy levels.
2. Valence electrons are the electrons available to be ____________, ______________, or _______________
in the formation of chemical compounds. They are often located in _________________________-filled
main energy levels. For main-group elements, the valence electrons are the electrons in the outermost
_____ and _____ sublevels.
F. – Electronegativity
1. Electronegativity is a measure of the ability of an atom in a chemical compound to __________________
electrons.
2. The most electronegative element is ________________________, and it is arbitrarily assigned an
electronegativity value of ______________.
3. Electronegativities tend to _____________________ across each period, although there are
__________________________.
a. The _____________ and ________________-earth metals are the least electronegative elements
b. Nitrogen, _________________, and the _______________________are the most electronegative
elements
4. Electronegativities tend to either _________________________ down a group or remain ______________
the _______________.
G. – Periodic Properties of the d- and f-Block Elements
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Chapter Review Problems
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#36, 41 and 46 from pages 157 and 158.