Chemistry Lesson 3
Atoms and Molecules
Learning Objectives:
In this chapter you will learn:

The organization and the predicting power of the modern periodic table.

The atomic structure

The electron configuration of an atom

Ionic bonding and the characteristic properties of ionic compounds

Covalent bonding and the characteristic properties of covalent compounds

How to predict the shape of a molecule

The types of intermolecular forces that hold molecules together.

Substances that have the giant covalent structure.

Hybridization of atomic orbitals and its implications to the molecular shape.
Suggested Time Allocation:
Part Theme
Powerpoint
Slides
Suggested time
allocation:
1
Atoms, Elements, Molecules and
Compounds
2–8
20 mins
2
The Modern Periodic Table
9 – 18
75 mins
3
Periodicity
19 – 22
30 mins
4
Atomic Structure
23 – 32
60 mins
5
Electron Arrangements
33 – 42
45 mins
6
Ionic Bond and Ionic Compounds
43 – 59
75 mins
7
Covalent Bond and Covalent Compounds
60 – 66
70 mins
8
Shape of a Molecule
67 – 72
45 mins
9
Intermolecular Forces
73 – 88
90 mins
10
Covalent Bond, Atomic Orbital,
Molecular Orbital and Hybridization
89 – 113
90 mins
Total time suggested:
600 mins
(10 hours)
Teachers Notes:
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This module covered quite a large numbers of topics about the Modern Periodic
Table, Atomic Structures, Molecular Structures, and Chemical Bonding. If time
is allowed, teachers are suggested to break down the module into several shorter
sessions. It allows students to learn the topics one by one, and so they can have
more time to digest the contents.
Knowledge prerequisites – it is recommended that the students have previously
learnt the following concepts:
- Differences between elements and compounds.
- The existence of some common elements such as hydrogen, oxygen,
nitrogen, carbon and chlorine.
- The three states of matter.
(Part 2) Students should know about the existence of semi-metals/metalloids,
and can remember 1-2 common examples. They should recognize that
metalloids have some typical properties that lie between those of metals and
non-metals. However, it is not necessary to discuss the details of these
characteristic properties, such as why the metalloids have semi-conducting
property.
(Part 2) Students should recognize all elements in Group VIII are extremely
chemically inert. It helps them to recognize the phenomenon that most
elements have strong tendency to form stable ions.
(Part 3) Students should recognize that the periodicities observed in the Periodic
table are only general trends, and minor discrepancies can frequently be
observed among these general trends.
(Part 4) Students should be reminded about the difference between relative
atomic mass, isotopic mass and mass number.
(Part 5) Students should recognize that the chemical and physical properties of
an element are closely related to its electron arrangement.
(Part 5) Slides 39-41 are included to illustrate why the outermost electrons of
potassium and calcium are put into the fourth shell instead of the partially filled
3rd shell. Teachers may choose to skip this part if they consider this part is a bit
side-tracked, or found the students have difficulty to follow.
(Part 6) Students should recognize that the formation of all types of chemical
bondings and intermolecular attractions (no matter whether they are ionic bonds,
covalent bonds, hydrogen bonding, polar-polar attraction or van der Waals’
forces) are due to the electrostatic attractions between opposite charges.
Different types of bonding/attractions give rise to attractions of different
strength.
10. (Part 9) Students should be reminded that a molecule having polar covalent
bonds can, as a whole, be overall non-polar (e.g. BF3). The polarity resulted
from the polar bonds cancels with each other.
11. (Part 9) Larger molecules have larger polarizability, giving rise to stronger
induced-dipole induced-dipole attraction.
12. (Part 9) Students should recognize that although non-polar molecules have no
permanent dipole moments, the electrons in a molecule move around
continuously and randomly. The random movements of electrons produce tiny
and instantaneous diploles for the molecules, and make the molecules weakly
attract to each other.
13. (Part 10) This part is an advanced part. Teachers may choose to skip this part.
14. (Part 10) Students should recognize that there are two different types of bonds
( and ) present in a multiple covalent bond.
15. (Part 10) Students should recognize that the geometry of a compound is
determined by the state of hybridization of its constituting atoms.
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Suggested Web-resources for Further Study:
1. http://www.webelements.com/
- WebElements: The periodic table on the web
2. http://en.wikipedia.org/wiki/Periodic_table
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- Wikipedia – Periodic table
http://www.college-cram.com/study/search/index.php?presentation=Atoms%20a
nd%20Molecules&owner=23&breadcrumb
- Atoms and Molecules – web resources at College-Cram.com
http://www.daviddarling.info/encyclopedia/B/Bohr_atom.html
- The Internet Encyclopedia of Science – Bohr atom
http://www.daviddarling.info/encyclopedia/R/Rutherfords_experiment_and_ato
mic_model.html
- The Internet Encyclopedia of Science - Rutherford’s experiment and atomic
model
http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr/patterns/electronsrev
1.shtml
- BBC GCSE Bitesize – Electron arrangement
http://www.saskschools.ca/curr_content/chem30/modules/module2/lesson2/perio
dtableandconf.htm
- Periodic table and electron arrangement
http://www.chem1.com/acad/webtext/chembond/
9.
Chem1 Virtual Textbook – Chemical Bonding and Molecular Structure
http://www.chem.ufl.edu/~itl/2045/lectures/lec_g.html
- Intermolecular forces
10. http://chemistry.boisestate.edu/people/richardbanks/inorganic/bonding%20and%
20hybridization/bonding_hybridization.htm
- Bonding and hybridization
11. http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/hybrv18.swf
Hybridization of orbitals – animations