(12+6) = 18
3
Tally the findings in the table with the positions of the elements in Table 1.1.
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Segmentation of the Periodic Table
As s-, p-, d-, and f-blocks of the Periodic table
Because of the importance of the outermost shell, the different regions of the perio-
dic table are sometimes referred to as periodic table blocks, named according to
the sub-shell in which the «last» electron resides, e.g. the s-block, the p-block, the d-block, etc.
Execise What commonality do you notice with the answers for exercise 1.1 with
regards to the outershell electronic configurations of sections a, b, and c?.
Answer: For; a) outermost orbitals have sx configuration (s1 or s2), b) outermost orbitals have px configuration (p1 or p3), c) outermost orbitals have dx configuration
(d1 or d7), d) outermost orbitals have filled s and p (maximum allowed number of
electrons) orbitals and are termed noble gases.
Thus elements in group 1 of the Periodic Table all have an outer electronic structure
of ns1 (where n is a number between 2 and 7). All group 2 elements have an outer
electronic structure of ns2. Elements in (a) above are in groups 1 and 2 and are des-
cribed as s-block elements.
The elements of groups 13 to 18 of the Periodic Table all have an outer electronic
structure of npx (where n is a number between 2 and 7 and x is a number between 1
and 6)., All these elements in (b) above are in p-block region of the periodic table.
The in (c) above are d-block elements and are elements in which the last electron
to be added to the atom is in a d orbital. They fall in groups 3 to 12 of the periodic
table. The first series of these contains the elements from scandium to zinc they are
also called transition elements or transition metals. The terms «transition element»
and «d-block element» don’t quite have the same meaning, but it doesn’t matter in
the present context.
While f-block elements are elements in which the last electron to be added to the
atom is in a f orbital. They are normally presented as a pull-out from the main periodic
table at the bottom (see figure 1.1)
Metals, Non-metals and metalloids
Metals fall into groups in the periodic table determined by similar arrangements of
their orbital electrons and a consequent similarity in chemical properties. Groups
of similar metals include the alkali metals and the alkaline-earth metals (s-block),
transition metals (d-block) and the rare-earth metals (the lanthanide and actinide
series of Group 3 see f-block). Most metals other than the alkali metals and the al-
kaline earth metals are called transition metals (see transition elements). Similarly
metallic properties do overlap into the p-block elements bordering the d-block (later
on diagonal relationship).
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Non-metals are found in the upper right hand side of the periodic table in the p-block
region. While metalloids are in the intersection between the metals and the non-metals
and they roughly form a right hand leaning diagonal from top to bottom across the
periodic table (see http://en.wikipedia.org/wiki/Periodic_table)
The six metalloids are B, Si, Ge, As, Sb, and Te. The properties of the metalloids
have characteristics in between that of the metals and the nonmetals. They are good
conductors of heat and electricity, but they are not perfect good conductors or insu-
lators.
Problem set Unit 1 (accounts for 7 %).
1. How many periods are there in the periodic table?
a)7,
b) 18, c) 8,
d)10.
2. How many valence electrons does argon have?
a) 18, b) 8, c) 3, d) 6
3. What is the group number of the halogens?
a) 7 b) 17, c) VIIA , d) 18
4. How many elements are in period 4?
a) 6
b) 8 c) 18 d) 4
5. The elements in the modern/present periodic table are arranged according to their,
a) atomic numbers,
b) atomic masses,
c) mass numbers,
d) oxidation states.
6. The majority of the elements in the periodic table are
a) metals,
b) non-metals, c)metalloids, d) Noble gases.
7. Elements in period 3 are alike in that they all have the same number of
a) Protons,
b) neutrons,
c) electrons in the valence shell
d) occupied principal energy levels.
Answer Key to Problem set Unit 1
1. a, 2. b, 3. b, 4. c, 5. a, 6.a, 7.d.
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Learning activity # 2
Title of Learning Activity : ATOmIC STRUCTURES And TREndS In THE s
And p BlOCK ElEmEnTS
At the end of this Unit, the learner should be able to
1. State the general trend and predict the atomic sizes of an elements an a
group/period.
2. State the general trend and predict the melting/boiling points of elements in
a group/period..
3. State the general trend and predict the ionization energies of elements in a
group/period.
4. State the general trend and predict the electronegativities of elements in a
group/period.
5. State the general trend and predict the electron affinities of elements in a
group/period.
6. State the general trend and predict the nuclear binding energies of elements
in a group/period.
7. State the general trend and predict the effective nuclear charge of elements
in a group/period.
Summary of the learning activity
In Unit 1 of this module we constructed, placed and classified elements accordingly in
the periodic table. This unit futher explores common trends in atomic sizes, ionization
enegies, electron affinities, electronegativities, and the nuclear binding energies of
the elements across the table. The learner will use excel program to graphically fol-
low and appreciate these trends. At the end of each topic, relevant worked examples
and excersises will follow to aid in the development of conceptual and quantitative
problem solving skills.
List of Required Readings
1. Alan G. Sharpe; Inorganic Chemistry, 3rd Edition. Longman Singapore Pu-
blisher, (1992).
2. Catherine E. Housecroft and Alan G. Sharpe; Inorganic Chemistry. Prentice-
Hall International, USA. (2000).
3. J. D. Lee, Concise Inorganic Chemistry, 4th edition. Chapman & Hall, New
York. USA. (1993).
4. Thomas R. Gilbert, Rein V. Kirss, and Geoffrey Davies; Chemistry, The
science in context. W.W. Norton and company NY, USA. (2004).
5. William L. Jolly, Modern inorganic Chemistry 2nd Ed. McGraw-Hill. Inc.
New York, USA (1991).
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List of relevant useful links
http://www.webelements.com/webelements/elements/text/periodic-table/econ.
html
For the properties of the elements and it is a live table. Once the table figure
is active, identify the property of interest on the left and just click on any
element in the Table and the details of the property sought for come along.
It will display the information wanted.
http://www.webelements.com/webelements/elements/text/Cu/ionz.html
This gives the particular properties of the element. In this case it is Cu. You
may substitute for Cu in the above URL and insert Cl for instance and get
the details for Chlorine.
www.chemicool.com
Provides an interactive Periodic Table that includes information about ele-
ments and their states, energies, characteristics, abundance, and costs.
education.jlab.org/itselemental/index.html
Allows user to search facts and information about elements by atomic num-
ber, chemical name, or chemical symbol.
www.webelements.com
Includes information on elements and their properties, discovery, history,
and uses.
http://en.wikipedia.org/wiki/Gold
Gives the different methods of calculating the electronegativity values.
http://www.chemguide.co.uk/atoms/bonding/electroneg.html
This page explains what electronegativity is, and how and why it varies around
the Periodic Table. It looks at the way that electronegativity differences affect
bond type and explains what is meant by polar bonds and polar molecules.
http://en.wikipedia.org/wiki/Electron_affinity
Shows electron affinity of various elements in a table form.
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/ionize.html, and http://
en.wikipedia.org/wiki/Ionization_energy
For interactive tables on ionization trends and data.
http://en.wikipedia.org/wiki/Binding_energy
Details on nuclear binding energy
http://en.wikipedia.org/wiki/Effective_nuclear_charge
For detailed effective nuclear charge
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List of relevant MULTIMEDIA resources
- Computer with internet connecting facility to access relevant links and free
source resourses.
- Multi-media resourses such as CD players, VCD etc.
- CD-ROM for this module for compulsory reading and demonstrations.
Learning activities
TRENDS IN s- AND p-BLOCK ELEMENTS
The main value of the periodic table is the ability to present the predictable properties
of an element based on its location on the table. It should be noted that the properties
vary differently when moving vertically along the columns of the table, than when
moving horizontally along the rows.
Consider the properties shown in table 2.1 below
Element
Atomic Group
Period
Melting Van de
Pauli
1st ionization
No.
points
waals/atomic electro-
energy
(oC)
radius (pm)
negativity (Kjmol-1)
(Xp)
Li
2
1
2
180
157
1.0