Outline
1.1 Chemistry: The Central Science
1.2 States of Matter
1.3 Classification of Matter
1.4 An Example of a Chemical Reaction
1.5 Chemical Elements and Symbols
1.6 Elements and the Periodic Table
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1.1 Chemistry: The Central Science
Chemistry is often referred to as “The Central Science”
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Chemistry: The study of the properties and
transformations of matter.
► Matter: Anything that has mass and occupies
space – things you can see, touch, taste, or smell.
► Property: A characteristic that can be used to
describe a substance. Substances have both
physical and chemical properties.
► Transformations: A change in the properties of
matter with time. There are physical changes and
chemical changes.
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Substances have both physical and chemical properties.
►Physical Properties: Density, color, and melting
point are physical properties of matter. Observing a
physical property can be done without altering the
makeup of a substance.
►Chemical Properties: Chemical composition, what
matter is made of, and chemical reactivity, how
matter behaves, are chemical properties. Observing a
chemical property alters the substance.
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Physical Change: Does not alter the chemical
makeup of a substance.
►Chemical reactivity is unchanged.
►Changes in state, changes in particle size, and
the formation / separation of mixtures are all
examples of physical change.
►Melting of ice to form liquid water is a physical
change. In this case only a change in form takes
place. The chemical makeup of the substance
remains H2O.
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Chemical Change: Alters
the makeup of a substance.
►Reactivity changes with
the formation of new
substances.
►Heat, light, or electrical
energy is often emitted or
absorbed.
►Potassium reacting with
water is an example of a
chemical change.
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Some Examples of Chemical and
Physical Changes
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1.2 States of Matter
Common states of matter are: solid, liquid, and gas.
►Solid: A substance that has a definite shape and
volume. Solids are rigid and dense.
►Liquid: A substance that has a definite volume
but that changes shape to fill the container. Liquids
are dense and fluid.
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Common states of matter are: solid, liquid, and gas.
►Gas: A substance that has neither a definite
volume nor a definite shape. Gases are low density
fluids.
►Substances can exist in each of these three states
depending on the pressure and the temperature. The
conversion of a substance from one state into
another is known as change of state.
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The three states - the solid state, the liquid state, and the
gaseous state - of water are shown below.
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1.3 Classification of Matter
►Pure Substance: Matter that is uniform in its
chemical composition and properties. Sugar is a pure
substance and water is a pure substance.
►Mixture: A blend of two or more pure substances in
any ratio, each retaining their identity. Dissolving sugar
in water creates a mixture.
►Physical changes can separate mixtures into one or
more pure substances. Evaporation and condensation
can separate water from sugar.
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► Element: Pure substance that cannot be broken
down chemically into simpler substances.
Hydrogen and oxygen are examples of elements.
► Chemical Compounds: Two or more elements
combined chemically in specific ratios to form a
pure substance. Water is a compound composed of
two parts hydrogen and one part oxygen.
► Chemical changes can separate chemical
compounds into elements. Water can be broken
down into hydrogen and oxygen by passing an
electric current through it.
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Pure Substances
A pure substance is classified as
• matter with a specific composition.
• an element when composed of one type of atom.
• a compound when composed of two or more elements
combined in a definite ratio.
ratio.
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Classification of Matter
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Learning Check
Identify each of the following as a pure substance or a mixture.
A. pasta and tomato sauce
B. aluminum foil
C. helium
D. air
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Solution
Identify each of the following as a pure substance or a mixture.
A. pasta and tomato sauce mixture
B. aluminum foil
pure substance
C. helium
pure substance
D. air
mixture
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The classification of matter is summarized below.
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1.4 Example of a Chemical Reaction
►Nickel, a solid metal, is mixed with
a colorless solution of hydrochloric
acid in a test tube.
►The nickel is slowly eaten away, the
colorless solution turns green, and a
colorless gas bubbles out of the test
tube.
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►Reactants: One or more starting materials. Between
reactants, the “+” can be read as “reacts with.”
►Products: One or more substances formed as a result
of a chemical reaction. Between products, the “+” can
be read as “and.”
►Between products and reactants, the “→” can be read
as “to form.”
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1.5 Chemical Elements and Symbols
► 114 elements have been discovered.
► 90 occur naturally.
► 24 are produced artificially.
► Some familiar elements are iron, tin, carbon,
oxygen, hydrogen, sulfur, etc.
► Some unfamiliar elements are niobium, rhodium,
thulium, californium, etc.
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►Each element has its own unique symbol. One or
two letter symbols are used to represent elements. The
first letter is always capitalized and the second letter is
always a lowercase. Examples: C, Cr, P, Pb
► Most symbols are derived from modern names and
are easy to remember. Examples: “H” for hydrogen,
“O” for oxygen, “N” for nitrogen, etc.
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► A few symbols for elements are derived from
their Latin names and are more difficult to learn.
Examples: “Na” for sodium comes from its Latin
name Natrium, “Pb” for lead comes from its
Latin name Plumbum.
► All naturally occurring elements are not equally
abundant. Oxygen and silicon together constitute
75% of the Earth’s crust.
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Memorize Me!
List of elements (name, location on the periodic table,
symbol, atomic number) to memorize
H, O, S, Ca, Sr,
Sr, Br, N, K, Cl
Cl,, C, P, Na, He, F, Ne, Ar,
Ar,
Kr, Xe
Xe,, Rn
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Chemical Formula: A notation for a chemical
compound using symbols and subscripts to show how
many atoms of each element are present. When no
subscript is given for an element a subscript of “1” is
understood.
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1.6 Elements and the Periodic Table
Periodic Table: 114 elements in tabular format.
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Large amounts of information regarding the properties
of elements are embedded in the periodic table.
Elements are roughly divided into 3 groups:
►
►
Metals: Found on the left side of the table.
Nonmetals: Found on the right side of the
table.
► Metalloids: Found along a diagonal line
between metals and nonmetals.
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A metal (red), a nonmetal (blue), and a metalloid
(green) appear in distinct places on the periodic table
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Metals: 90 of the 114 elements are metals. They
appear on the left side of the periodic table.
Some common properties of metals are:
► Solid at room temperature (except mercury
which is a liquid)
► Good conductor of heat and electricity
► Lustrous on fresh surfaces
► Malleable and ductile
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Metals:
(a) Gold is very unreactive and is used primarily in jewelry and in
electronic components.
(b) Zinc, an essential nutrient, is used in the manufacture of brass,
roofing materials, and batteries.
(c) Copper is widely used in electrical wiring, in water pipes, and
in coins.
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Nonmetals: Appear on the right side of the periodic
table. 17 elements are nonmetals.
► Eleven are gases at room temperature (H, N, O,
F, Ne, etc.).
► Five are solids (C, P, S, Se, I).
► One is a liquid (Br).
► Nonmetals are poor conductors of heat and
electricity.
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Nonmetals:
(a) Nitrogen constitutes almost 80% of air and is a
colorless gas at room temperature.
(b) Sulfur, a yellow solid, is found in large underground
deposits in Texas and Louisiana.
(c) Bromine is a corrosive, dark red liquid.
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Metalloids: Seven elements are metalloids. Their
Metalloids:
properties are between those of metals and
nonmetals. Metalloids are semiconductors and are
important to the electronics industry. (a) Boron and
(b) silicon are examples of metalloids.
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Chapter Summary
►Matter is anything with mass that occupies volume.
►Matter can be classified as solid, liquid, or gas.
►A solid has a definite volume and shape, a liquid has
a definite volume but indefinite shape, and a gas has
neither a definite volume nor shape.
►A substance can be characterized as being either pure
or a mixture.
►A pure substance is uniform in its composition and
properties, but a mixture can vary in both composition
and properties.
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Chapter Summary Cont.
►Pure substances are either elements or chemical
compounds.
►Elements are fundamental substances that cannot be
chemically changed into anything simpler.
►A chemical compound can be broken down by
chemical change into simpler substances.
►A property describes or identifies something.
►A physical property can be seen or measured
without changing the chemical identity of the
substance.
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Chapter Summary Cont.
► A chemical property can only be seen or measured
when the substance undergoes a chemical change.
► Elements are represented by symbols. Most symbols
are the first one or two letters of the element name.
► Some symbols are derived from Latin names.
► All the known elements are organized into a tabular
form called the periodic table.
► Most elements are metals, 17 are nonmetals, and 7
are metalloids.
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