Transcript An Introduction to Chemistry

In this lesson,
we will discuss
the following:
Chemical Size
Properties
Changes
Naming
Compounds
An Introduction to
Chemical Concepts
Chemistry
Let’s Do a
Crossword
Puzzle!
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Categorizing Chemicals by Size
• SUBMICROSCOPIC: Anything which is too
small to be seen with an optical microscope is
considered to be submicroscopic.
• MICROSCOPIC: Anything that is too small to
be seen with the naked eye but is large
enough to be seen with an optical microscope
is considered to be microscopic.
• MACROSCOPIC: Anything that is large enough
to be seen with the naked eye is considered to
be macroscopic.
Categorizing Chemicals by Size
In chemistry, we will be discussing microscopic
and submicroscopic particles, and how they
affect what we see in the macroscopic world.
Properties
We will discuss two
kinds of properties:
• Physical Properties
• Chemical Properties
Physical Properties
Examples of
physical properties:
• PHYSICAL PROPERTIES are •defined
Melting as
point
• Color
properties which can be observed
without
• Luster
changing a substance into another
substance
• Hardness
(or group of substances).
• Texture
Chemical Properties
Examples of
chemical
properties:
Tendencyas
to
• CHEMICAL PROPERTIES are•defined
react with water
properties that can be observed
only by
• Tendency to
changing one substance into a new
substance
combust
(or group of substances). • Tendency to
decompose
• Physical and chemical
properties can be divided
into two smaller categories:
– Intensive properties and
– Extensive properties.
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Changes
We will discuss two
kinds of changes:
• Physical Changes
• Chemical Changes
Physical Changes
• A PHYSICAL CHANGE changes some
characteristic (or characteristics) of a
substance without actually changing what the
substance is.
Chemical Changes
• A CHEMICAL
CHANGE (or
chemical
reaction) is
the change of
a substance
into a new
substance (or
group of
substances).
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physical and
chemical changes.
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Chemical Changes
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• The atoms present before a chemical
change are still present after the
chemical change.
• The atoms are just rearranged to
form new substances.
Chemical Changes
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The transformation of oxygen, O2, into ozone, O3,
is an example of
O=O
O
O
O
O O
O
oxygen
A.
B.
C.
D.
a physical change.
a chemical change.
both a physical and chemical change.
neither a physical nor chemical change.
ozone
The transformation of oxygen, O2, into ozone, O3,
is an example of
O=O
O
O
O
O O
O
oxygen
A.
B.
C.
D.
a physical change.
a chemical change.
both a physical and chemical change.
neither a physical nor chemical change.
ozone
Elements Versus Compounds
• ELEMENTS: An element is defined as a
substance made of only one kind of atom.
• COMPOUNDS: A compound is defined as a
substance made of two or more kinds of
atoms in a CHEMICAL combination.
– A compound is made of elements, but a
compound is uniquely different from the
elements which make it up.
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Which of the following boxes contains an element?
A compound?
A
B
A. Element: A, C
Compound: A, B, C
B. Element: C
Compound: A, B
C. Element: C
Compound: B
D. Element: A, C
Compound: A, B
C
Which of the following boxes contains an element?
A compound?
A
B
A. Element: A, C
Compound: A, B, C
B. Element: C
Compound: A, B
C. Element: C
Compound: B
D. Element: A, C
Compound: A, B
C
Naming Compounds
• IONIC COMPOUNDS: An ionic
compound is a substance made of a
negatively-charged ion chemically
combined with a positively-charged
ion.
– Many ionic compounds are made of
one kind of metal ion and one kind of
nonmetal ion.
• COVALENT COMPOUNDS: A
covalent compound is a substance
made of more than one nonmetal
combined chemically.
An ION is
just an atom
with a net
charge.
Naming Type I Ionic Compounds
A Type I ionic compound is made up of a metal
and a nonmetal. Only metals which form ions
with one charge take part in forming Type I ionic
compounds.
Naming Type I Ionic Compounds
In order to name a Type I ionic compound, you
should do the following:
1. Write down the name of the metal atom first.
The metal atom is farther left on the Periodic
Table than the nonmetal atom.
2. Write down the name of the nonmetal atom
next. Give the name an “ide” suffix.
Naming Type I Ionic Compounds
Example:
What is the name of LiBr?
Solution:
Write down
the name of
the metal
atom first.
Lithium bromide
Next, write
down the
name of the
nonmetal
atom. Give
the nonmetal
the “ide”
ending.
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with naming
ionic
compounds.
Naming Covalent Compounds
• A covalent compound is made of two or more
nonmetals in a chemical combination.
Naming Covalent Compounds
When naming a covalent compound, you should
do the following:
1. Write the name of the first kind of atom in
the chemical formula. Use the appropriate
prefix if necessary.
2. Write the name of the second kind of atom in
the chemical formula. Use the appropriate
prefix if necessary, and use the “ide” suffix.
Naming Covalent Compounds
• Some of the suffixes used when naming
covalent compounds follow:
– Mono = 1
– Di = 2
– Tri = 3
– Tetra = 4
– Penta = 5
– Hexa = 6
– Hepta = 7
– Octa = 8
Naming Covalent Compounds
• The prefix “mono” should not be used with
the first atom in a covalent compound.
Naming Covalent Compounds
Example:
Name the following compound:
CO
Write down
the name of
the first atom.
Use the
appropriate
prefix if
necessary.
Solution:
Carbon monoxide
Next, write
down the
name of the
second atom.
Give it the
appropriate
prefix if
necessary
and the “ide”
ending.
Naming Covalent Compounds
Example:
Name the following compound:
CO2
Write down
the name of
the first atom.
Use the
appropriate
prefix if
necessary.
Solution:
Carbon dioxide
Next, write
down the
name of the
second atom.
Give it the
appropriate
prefix if
necessary
and the “ide”
ending.
Naming Covalent Compounds
Example:
Name the following compounds:
H2O and H2O2
Write down
the name of
the first atom.
Use the
appropriate
prefix if
necessary.
Solution:
Dihydrogen
monoxide
and
Dihydrogen dioxide
Next, write
down the
name of the
second atom.
Give it the
appropriate
prefix if
necessary
and the “ide”
ending.
Sometimes Common Names are Used
for Compounds
Example:
Name the following compounds:
H2O and H2O2
Or, they are called
Water
and
Hydrogen peroxide
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The web page
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gives a little
extra help
with naming
covalent
compounds.