Chemistry

1
Chemistry
Grade 10 Advanced
Unit 1
STRUCTURE AND BONDING IN MATTER
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2
Unit 1
STRUCTURE AND BONDING IN MATTER
By the end of the chapter, most students know the
mass and charge in atoms and ions up to element
56 .Show how the electronic structure explains
the patterns of elements in the periodic table
and manipulate quantities such as proton number
and mass number. They understand ionic, covalent
and metallic bonding in terms of bond types. They
write balanced molecular and ionic equations for
simple reactions. They explain the
macro-properties of the different states of
matter in terms of their micro-structure.
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3
Unit 1 Structure and bonding in matter
Ceramics????????
17.14 Explain the strength, high melting point
and electrical insulating properties of ceramics
in terms of their giant molecular structure and
relate these properties to their uses. 17.14????
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Key Vocabulary strength insulating ceramics
Objectives 1. Explain the strength, high
melting point and electrical insulating
properties of ceramics in terms of their giant
molecular structure. 2. Relate properties of
ceramics to their uses.
Ceramics can be defined as heat-resistant,
nonmetallic, inorganic solids that are
(generally) made up of compounds formed from
metallic and nonmetallic elements. ????? ?????
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? ??? ???????? ? ???? ?? ??? ??????? (?????)
????? ?? ?????? ????? ?? ??????? ???????? ????
????????. Ceramics include objects made of clay
and cements that have been hardened by heating at
high temperatures. ????? ???????? ??????
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Properties and uses
For centuries ceramics were used by those who had
little knowledge of their structure. ?????
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??????? ???????. Today, understanding of the
structure and properties of ceramics is making it
possible to design and engineer new kinds of
ceramics. ????? ??? ??????? ??????? ??????
???????? ??? ?? ?????? ?????? ????? ????? ??
????????.
4
Unit 1 Structure and bonding in matter
Most ceramics are hard, chemically inert ,
refractory (can withstand very high heat without
deformation), and poor conductors of heat and
electricity. Ceramics also have low densities.
These properties make ceramics attractive for
many applications. ???? ???????? ???? ? ?????
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?????. ?? ??? ??????? ???? ???????? ?????? ??
???????????. Ceramics are used as refractoriness
in furnaces and as durable building materials (in
the form of bricks, tiles, cinder blocks, and
other hard, strong solids). ??????? ????????
????? ?????? ??????? ?? ??????? ?????? ???? ???
????? ????? (?? ???? ????? ? ????? ? ????? ??
??????? ?????? ????? ???? ????? ????) They are
also used as common electrical and thermal
insulators in the manufacture of spark plugs,
telephone poles, electronic devices, and the nose
cones of spacecraft. However, ceramics also tend
to be brittle. ??? ???? ?????? ??? ?? ????
?????? ???????? ??????? ??? ????? ????? ??????? ?
????? ?????? ? ??????? ??????????? ? ????????
????????? ???????? ????????. ??? ??? ? ????
???????? ?? ???? ???. A major difficulty with
the use of ceramics is their tendency to acquire
tiny cracks that slowly become larger until the
material falls apart. To prevent ceramic
materials from cracking, they are often applied
as coatings on inexpensive materials that are
resistant to cracks. For example, engine parts
are sometimes coated with ceramics to reduce heat
transfer. ???? ????? ????? ?? ??????? ?????????
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http//www.chemistryexplained.com/Bo-e/Ceramics.h
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5
Unit 1 Structure and bonding in matter
Exercises
Explain ???? 1. Ceramics are
hard materials? ?????? ??????? ???? ????
2. Ceramics are used in furnace lining and space
shuttle head tiles? ?????? ???????? ??????
??????? ??????? ????? ???????? ?????????
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Unit 1 Structure and bonding in matter
Composites Materials ?????? ???????
17.15 Know the commercial and industrial
importance of composite materials that combine
the properties of their constituents, and give
examples. ???? ??????? ???????? ????????? ??????
??????? ???? ???? ??? ????? ?????????????? ?????
??? ???.
Key Vocabulary commercial composite materials
Objectives Student will be able to 1. Know
the commercial and industrial importance of
composite materials.
Composite materials are formed by combining two
or more materials that have quite different
properties. ????? ?????? ??????? ?? ???? ?????
??? ????? ?? ???? ?? ?????? ???? ??? ????? ??????
?????. The different materials work together to
give the composite unique properties, but within
the composite you can easily tell the different
materials apart they do not dissolve or blend
into each other. ?????? ???????? ???? ??? ??????
?????? ??????? ????? ????? ? ???? ???? ??????
??????? ???? ?? ????? ?????? ??? ?????? ????????
-- ???? ?? ???? ?? ???? ?? ?????
?????. Composites exist in nature. A piece of
wood is a composite, with long fibres of
cellulose (a very complex form of starch) held
together by a much weaker substance called
lignin. ?????? ??????? ?????? ?? ???????. ???? ??
????? ???? ????? ? ?? ????? ????? ?? ????????
(??? ??? ???? ??? ?? ?????) ???? ???? ??? ?? ????
???? ????? ???? ???????.
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Unit 1 Structure and bonding in matter
Another well-known composite is concrete. Here
small stones or gravel is bound together by
cement. Concrete has good strength under
compression, and it can be made stronger under
tension by adding metal rods, wires, mesh or
cables to the composite (so creating reinforced
concrete). ???? ??? ????? ?? ???????? . ?????
??????? ??????? ?? ????? ?????? ??? ??????
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(?????? ???????? ???????) Most composites are
made up of just two materials. One material
(the matrix or binder) surrounds and binds
together a cluster of fibres or fragments of a
much stronger material (the reinforcement). ?????
???? ?????? ??????? ?? ?????? ????? ???. ???? ??
(?????? ?? ???????) ???? ????? ??? ?????? ??
??????? ?? ????? ?? ???? ???? ????? ( ????
???????)
So why use composites? ??? ????? ?????? ??????
??????? ?
The greatest advantage of composite materials is
strength and stiffness combined with
lightness. ???? ???? ?????? ??????? ???? ??????
???? ??? ??? ?? ???.
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Unit 1 Structure and bonding in matter
By choosing an appropriate combination of
reinforcement and matrix material, manufacturers
can produce properties that exactly fit the
requirements for a particular structure for a
particular purpose. ??????? ?????? ?????? ??
?????? ??????? ????? ?????? ? ???? ???????? ??
???? ??????? ???? ????? ????? ??????? ???? ?????
???? ????. Modern aviation, both military and
civil, is a prime example. It would be much less
efficient without composites. In fact, the
demands made by that industry for materials that
are both light and strong has been the main force
driving the development of composites. ???????
?????? ??????? ? ???????? ???? ???????? ??? ???
???? ??? ???. ?????? ??? ????? ?? ??? ??????
???????. ?? ?????? ? ???? ??????? ??? ???????
????? ????? ????? ????? ??????? ???????? ??????
?????? ???????. It is common now to find wing
and tail sections, propellers and rotor blades
made from advanced composites, along with much of
the internal structure and fittings. The
airframes of some smaller aircraft are made
entirely from composites, as are the wing, tail
and body panels of large commercial aircraft. ??
?????? ???? ?? ??? ????? ?????? ?????? ??????
?????? ??????? ?????? ?? ???? ????? ??????? ????
??? ??? ?? ?????? ?? ??????? ?????? ??????? .
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???????? ??????. The right composites also stand
up well to heat and corrosion. This makes them
ideal for use in products that are exposed to
extreme environments such as boats,
chemical-handling equipment and spacecraft. In
general, composite materials are very
durable. ?????? ??????? ???????? ???? ????? ?????
??????? ??????. ???? ?????? ?????? ????????? ??
???????? ???? ??? ?????? ??????? ????? ???????
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????? ????.
9
Unit 1 Structure and bonding in matter
The downside of composites is usually the cost.
Although manufacturing processes are often more
efficient when composites are used, the raw
materials are expensive. ?????? ?????? ??????
??????? ?? ???? ?? ???? ???????. ??? ????? ?? ??
?????? ??????? ?? ???? ?? ??????? ???? ????? ???
??????? ?????? ??????? ??? ?? ?????? ?????
?????. Composites will never totally replace
traditional materials like steel, but in many
cases they are just what we need. And no doubt
new uses will be found as the technology evolves.
We havent yet seen all that composites can
do. ??????? ??????? ?? ??? ?????? ??? ??????
????????? ??? ?????? ?????? ?? ???? ?? ??????? ??
?? ????? ???? ???. ???? ?? ?? ??? ????? ?????????
????? ?? ???? ???????????. ?? ?? ??? ???? ?? ??
???? ?? ????? ?????? ???????. Another
advantage of composite materials is that they
provide design flexibility. Composites can be
moulded into complex shapes a great asset when
producing something like a surfboard or a boat
hull. ???? ???? ?????? ??????? ???? ???? ?????
???????. ???? ?? ????? ??? ????? ????? ????????
???? ????? ??????????? ???? ???? ??? ????? ????
??????? ?? ??? ?????.
http//www.science.org.au/nova/059/059key.htm

10
Unit 1 Structure and bonding in matter
Exercises
Q1)What is meant by composites Materials? _______
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_____________________ Q2) What are the
properties of composites? _______________________
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_____ Q3) Why do we prefer using composites in
industries more than in the single constituents
alone? __________________________________________
_____________________ ___________________________
____________________________________ Q4) Mention
some applications for composites. _______________
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