I. Chemistry is a Physical Science
Objectives:
• Define chemistry.
• List examples of the branches of
chemistry.
• Compare and contrast basic research,
applied research, and technological
development
III. What
Chemistry?
What isIsChemistry?
1)
chemistry
=
the
study
of
the
composition,
1) Chemistry = the study of the
structure,
and properties
ofand
matter
and the
composition,
structure,
properties
changes
it undergoes
of matter
and the changes it undergoes.
6 Branches of Chemistry
1. Organic chemistry = study of carbon-containing
compounds
2. Inorganic chemistry = study of all substances not
classified as organic, mainly those compounds that
do not contain C
3. Physical chemistry = study of the properties and
changes of matter and their relation to energy
4. Analytical chemistry = identification of the
components and composition of materials
5. Biochemistry = study of substances and processes
occurring in living things
6. Theoretical chemistry = use of mathematics and
computers to understand the principles behind
observed chemical behavior and to design and
predict the properties of new compounds.
Science vs. Technology
• Science includes knowledge in the major disciplines,
such as biology, chemistry, and physics.
• Technology is the application of that knowledge for
practical purposes.
• Basic research = research conducted for the sake of
knowledge only and not to meet practical goals
• Applied research = research conducted to meet goals
defined by specific needs
• Technology = applies existing knowledge to make life
easier or more convenient
II. Matter and Its Properties
Objectives:
• Distinguish between the physical properties
and chemical properties of matter.
• Classify changes of matter as physical and
chemical.
• Explain the gas, liquid, and solid states in
terms of particles.
• Distinguish between a mixture and a pure
substance.
Energy vs. Matter
• EVERYTHING that you see or sense is
either matter or the interaction of energy
and matter!
1) Energy = the ability to cause change or
the ability to do work.
2) Matter = anything that has mass and
takes up space.
Classification of Matter
1) Pure substance = a type of matter that has a
consistent, fixed composition no matter where
the sample is obtained.
a) Ex: water (a pure substance) is ALWAYS
11.2% hydrogen and 88.8% oxygen (by
mass).
• So a molecule of water from India has the
same compositions as a molecule of water
from Canada.
b) PURE SUBSTANCES are either elements
or compounds
V. Classification
ClassificationofofMatter
Matter
2) element = pure substance made of only one
2) Element = pure substance made of only
kind of atom
one kind of atom.
a) atom = smallest unit of an element that
a) atom = smallest unit of an element
maintains the properties of that element
that maintains the properties of that
element.
V.Classification
Classificationofof
Matter
Matter
3) compound = a pure substance that is made
3)from
Compound
= aofpure
that is that
the atoms
two substance
or more elements
made
from the atoms
of two or more
are chemically
combined
elements that are chemically combined.
a) Individual elements lose their individual
a) Individual elements lose their
properties and take on the new properties
individual properties and take on the
of
the
compound
that
is
formed.
new properties of the compound that is
formed.
b)Ex: sodium
sodium (an
(an element)
element) isis aa highly
highly reactive
reactive
b)Ex:
b)
Ex:
sodium
(an
element)
is
a
highly
b)Ex:
sodium
(an
element)
is
a
highly
reactive
b)Ex:
sodium
(an
element)
is
a
highly
reactive
b)Ex:
sodium
(an
element)
is
a
highly
reactive
metal
and
chlorine
(an
element)
is
a
b)Ex:
sodium
(an element)
is a highly
reactive
metal
and
chlorine
(an(an
element)
is(an
ais aelement)
reactive
metal
and
chlorine
metal
and
chlorine
element)
metal
and
chlorine
(an
element)
isisathey
metal
and
chlorine
(an
element)
a
poisonous
gas;
chemically
combined
metal
and
chlorine
(an
element)
isthey
athey
poisonous
gas;gas;
chemically
combined
is
a
poisonous
gas;
chemically
poisonous
chemically
combined
poisonous
gas;
chemically
combined
they
poisonous
gas;
chemically
combined
they
form
sodium
chloride
(a
compound)
which
is
poisonous
gas;
chemically
combined
they
form
sodium
chloride
(a compound)
which
is (a
combined
they
form
sodium
chloride
form
sodium
chloride
(a
compound)
which
is
form
sodium
chloride
(a
compound)
which
is
form
sodium
chloride
(a
compound)
which
is
common
table
salt
form sodium
chloride
(a
compound)
which
is
common
table
salt
compound)
which
is
common
table
salt.
common
table
salt
common
table
salt
common
table
salt
common table salt
++
+
→→
→
→
Classification of Matter
4) Mixture = a blend of two or more pure
substances that are physically combined
where each pure substance retains its own
identity and properties
• Ex: silver coins + gold coins = mixture;
the silver coins are still silver coins and
the gold coins are still gold coins.
V. Classification of Matter
• Characteristics of mixtures:
1. Represent physical combinations of two
more substances
2. Substances do not lose their original
properties.
3. Substances can be separated by
physical means.
• Two types of mixtures are homogeneous
and heterogeneous.
5) Homogeneous mixture (solution) = a
mixture that is uniform in composition
throughout an entire sample.
• Ex: if you were to take one scoop out of
one area of a homogeneous mixture and
a second scoop out of a different area of
the same sample, the composition of
each scoop would be essentially the
same.
• Ex: salt water, air, window glass.
Homogeneous mixture cont.
• Also called solutions – consist of a solute
(dissolved material) in a solvent
(dissolving material)
• Important symbol in chemistry is
the subscript “aq”, which stands for
aqueous.
• An aqueous substance is one that is
dissolved in water … AKA a solution!
• NaCl(s) – This formula represents a solid
substance, the compound NaCl in a solid
form.
• NaCl(aq) – This formula represents a
homogeneous mixture of NaCl and water.
6) Heterogeneous mixture = a mixture that
is NOT uniform in composition throughout
an entire sample.
• Ex: chicken soup, sands, soil.
Matter
Anything that has both mass & volume
Ex: Sodium chloride, Oxygen
Pure Substance
Mixture
Matter with constant
composition. All particles
have the same properties
Matter with variable
composition. Made from two
or more substances
Ex: Water, Helium
Ex: Sand, soil
Element
A substance
made up of
only one kind
of atom
Ex: Lead,
Sodium
Compound
A substance
made from two or
more elements,
chemically
combined
Ex: Carbon
dioxide
Homogeneous
Mixture
(Solution)
A mixture made
up of particles
that are
uniformly
distributed.
Ex: Salt water
Heterogeneous
Mixture
A mixture made
up of particles
that are not
uniformly
distributed.
Ex: Raisin bran
How would you classify the
following matter?
ASPIRIN (C9H8O4) is composed of 60%
carbon, 4.5% hydrogen, and 35.5% oxygen
by mass, regardless of its source.
Is aspirin a mixture or a pure substance?
Pure substance – constant composition
Element or compound?
Compound
How would you classify the
following matter?
SALT WATER
Is salt water a mixture or a pure substance?
Mixture – can be separated by evaporation
What type of mixture?
Homogeneous mixture
Properties of Matter
•
•
1.
2.
•
•
What is a property?
2 methods of grouping properties
Extensive and intensive
Physical and chemical
Extensive = property that depends on the
amount of matter (mass, volume)
Intensive = property that does not depend
on the amount of matter present (color,
melting pt., boiling pt.)
Properties of Matter
1) Physical property = a characteristic that
can be observed or measured without
changing the identity of a material.
• Physical properties describe matter.
• Ex: state, color, odor, solubility, density,
melting point, boiling point, hardness,
mass, texture
Properties of Matter
2) Chemical property = the ability of a
substance to undergo a change that alters
its identity.
• Chemical properties describe the ability
of matter to change identity.
• Ex: flammability, reactivity with acid,
resistance to rusting, ability to
decompose.
Changes
1) Physical change = any change in a
property of matter that does NOT result
in a change in identity.
• Ex: water freezing, water vapor
condensing, wood being chopped, glass
being broken, an iron rod being bent
Changes
2) Chemical change (chemical reaction) =
a change in which one or more substances
are converted into different substances
with different characteristic properties.
• Ex: paper burning, silver tarnishing,
wood decomposing, iron rusting.
Chemical
Physical
change:
Chemical vs.
vs. Physical
Change:
Chemical change
(chemical reaction)
1) Indications of a chemical change
(reaction):
a) Evolution of heat and light
b) production of a gas (seen as bubbles)
c) color change
d) formation of a precipitate when two
solutions are mixed.
 precipitate = a solid that separates from a
solution.
Formation of a PRECIPITATE
Precipitate of cadmium
sulfide forms from
clear solutions of
sodium sulfide and
cadmium nitrate.
Chemical change
(chemical reaction)
2) In order for a chemical reaction to take
place, the reactants must have the ability to
form chemical bonds.
• Parts of a chemical reaction:
– REACTANTS = substances that interact with
each other. On the left side of the arrow in a
chemical equation.
– PRODUCTS = new substances formed
during reaction. On the right side of the
arrow in a chemical equation.
– EX: hydrogen + oxygen  water + heat
Chemical change
(chemical reaction)
3) Law of Conservation of Matter = matter is
neither created nor destroyed during ordinary
chemical and physical changes.
• As a result of the law of conservation of matter,
the mass of the reactants in a chemical reaction
must EQUAL the mass of the products.
• If you START off with 10g of matter before a
physical or chemical reaction, you will END up
with 10g of matter.
– These changes don’t create or destroy atoms, they
only change how the atoms are bonded to each
other!
Energy Changes
1) Energy = the ability
to cause change or
the ability to do work
• Heat = form of energy
– Heat FLOWS from
objects with a high
temperature to objects
with a lower
temperature.
Energy Changes
NOTE: A chemical change is ALWAYS
accompanied by a change in ENGERGY!!
2) Chemistry deals with the chemical
energy stored in matter and with either the
effects on matter or the production of
energy from matter.
Energy Changes
3) Activation energy is the energy needed
to start a chemical reaction.
• All chemical reactions require energy to
begin!
– Enough energy is available from the
environment to start some reactions.
– For others, additional energy must be added
before the reaction will begin.
Energy Changes
4) Endothermic process = a
process that absorbs heat
• The products have MORE
energy than the reactants.
• Energy must be absorbed
as the products form.
• The container in which an
endothermic reaction is
taking place will feel cold.
• Ex: chemical cold packs, ice
melting.
Energy Changes
5) Exothermic process = a
process that releases heat.
• The reactants have MORE
energy than the products.
• Energy must be released
as the products form.
• The container in which an
exothermic reaction is
taking place will feel hot.
• Ex: chemical hot packs,
lighting a match.
Exothermic process
Ex: CH4 (g) + 2O2 (g)  CO2 (g) + 2H2O (g) + ENGERY
REACTANTS
PRODUCTS
4 States of Matter
1. Solid = definite volume and definite
shape
2. Liquid = definite volume but no definite
shape
3. Gas = neither definite volume nor
definite shape
4. Plasma = high-temperature physical
state of matter in which atoms lose their
electrons
III. Elements
Objectives:
• Use a periodic table to name elements,
given their symbols.
• Use a periodic table to write the symbols
of elements, given their names.
• Describe the arrangement of the periodic
table.
• List the characteristics that distinguish
metals, nonmetals, and metalloids.
• For a chemist, the periodic table is the
most useful source of information about
the elements.
• Groups = families = vertical columns
(these elements have similar properties)
• Periods = horizontal rows
• Symbols are sometimes derived from
Latin.
Write the symbol, group, and
period for each of the following:
1.
2.
3.
4.
5.
Potassium
Oxygen
Aluminum
Cesium
Sodium
6. Sulfur
7. Zinc
8. Cobalt
9. Neon
10.Iodine
Types of Elements
• 3 Types:
– Metals: good conductor of heat and electricity
• other properties include: malleability, tensile
strength, ductile, solid at room temp. silvery or
grayish luster, reactivity
• Majority of periodic table
– Nonmetals: poor conductor of heat and
electricity
• Other properties include: many are gases; solids are
brittle
• Top right corner of periodic table
Types of Elements
– Metalloids: properties of metals and
nonmetals
• Other properties include: semiconductors of
electricity, used in computers and calculators
• 6 elements form stair steps (B, Si, Ge, As, Sb, and
Te)
Noble Gases
• Noble gases = group 18
• Unreactive
• Gases at room temp.
Complete p. 23 #1,2,4-15, 2021
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