Transcript Unit 3 - Chemistry

Introduction to Chemistry
• Study of the _______________ of
matter and the _______________
matter undergoes.
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Organic chemistry Inorganic chemistry Analytical chemistry Physical chemistry
Biochemistry -
Understanding Concepts
• Chemistry deals with _______________
facts - facts that can be discovered by
making observations and doing
experiments.
• It is often necessary to rely on
information that others have discovered.
Diamond
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Hardest known substance.
A form of the element carbon.
Highly ordered molecular structure.
Not the most stable form of carbon.
Macro vs. Micro
• _______________ - things you see
with the unaided eye or large scale
experimenting.
• _______________ - things too small
to see with the unaided eye - or
small scale experimenting.
Matter and Change
Matter
• Anything that has _______________
and takes up _______________.
• Everything is made up of matter.
Definitions for Components of Matter
_______________ - the simplest type of substance with unique
physical and chemical properties. An element consists of only
one type of atom. It cannot be broken down into any simpler
substances by physical or chemical means.
_______________ - a structure that consists of
two or more atoms that are chemically bound
together and thus behaves as an
independent unit.
Definitions for Components of Matter
_______________ - a substance
composed of two or more elements
which are chemically combined.
_______________ - a group of two or
more elements and/or compounds
that are physically intermingled.
• _______________ - amount of matter
the object contains - measured in
grams.
• _______________ - matter that has
uniform and definite _______________
(pure substances) - contain only one
kind of matter.
Physical Properties
• Quality or condition of a substance that
can be observed or measured without
changing the substance’s composition.
• Color
• odor
• hardness
• density
• melting & boiling points
• solubility
• Physical properties help chemists
_______________ substances.
States of Matter
• _______________
- definite shape
and volume.
• Particles are packed tightly together.
• Almost incompressible.
• Expand only slightly when heated.
• _______________
- indefinite shape
and definite volume.
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In close contact with one another.
Liquids can flow.
Almost incompressible.
Tend to expand when heated.
• _______________
- indefinite shape
and volume.
• Gas particles are far apart.
• Easily compressed.
• Expand without limit to fill any space.
• _______________ - describes the
gaseous state of a substance that is
generally a liquid or solid at room
temperature (different than a gas).
Physical Change
• _______________ can be changed in
many ways without changing the
_______________ composition of the
material.
• Cutting
• Dissolving
• Crack
• Grinding
• Melting
• Boiling
• Bending
• Freezing
• Crush
• Tearing
• Condensing • Break
Melting or Freezing of Water
• Melting ice into liquid is a physical
change, along with changing liquid to
steam and steam to condensation.
• There is no alteration to the chemical
composition of water, only a change of
state.
Classifying Mixtures
• _______________ blend of two or more
substances.
• Compositions may vary.
Heterogeneous Mixture
• Not uniform in _______________.
• If you were to separate the mixture into
portions, each portion would be different
from the other.
Homogeneous Mixture
• Completely _______________
throughout.
• Components are evenly distributed
throughout.
• Separate the mixture into portions and
the portions would be the same.
• Also called _______________ - may be
gases, liquids, or solids.
Atomic Structure
&
the Periodic Table
Early Models of the Atom
• John Dalton
• English teacher
• 1766-1844
• Studied ratios of elements in
chemical reactions.
• Formulated hypotheses and
theories to explain his
observations and came up with
Dalton’s atomic theory.
Dalton’s Atomic Theory
The Postulates
1. All matter consists of ___________________.
2. Atoms of one element cannot be converted into
atoms of another element.
3. Atoms of an element are identical in mass and other
properties and are different from atoms of any other
element.
4. _______________ result from the chemical combination of
a specific ratio of atoms of different elements.
• His model was not accepted at first,
however, he used his model to explain
the existence of certain types of
substances.
• He predicted correctly the formation of
multiple compounds and his theory
became widely accepted.
Atoms
• The smallest _______________ that
cannot be divided any further and still
maintain the _______________ of the
substance.
Structure of an Atom
• J.J. (John Joseph) Thomson, physicist
• 1890-1900
• Showed that the atoms of any element can be
made to emit tiny negative particles - called
_______________.
• Thompson knew that the entire atom was not
negatively charged so he concluded that the
atom must also contain _______________
particles that balance the negative charge, giving
the atom a _______________ overall charge.
J.J. Thomson
• J.J. Thomson was chosen to
head the Cavendish Laboratory
in Cambridge, England in 1884
when he was only 28 years old.
• Thomson was known for his gift
in designing experiments, but
he was not mechanically
inclined and needed help to
build the apparatus needed to
perform the experiments.
Structure of an Atom
• William Thomson (Lord Kelvin, no relation to
J.J. Thomson)
• ______________________________
• He had the idea that the atom might be something
like a pudding with raisins randomly distributed
throughout.
• He reasoned that the atom might be thought of as
a uniform pudding of positives charge with enough
negative electrons scattered within to
counterbalance that positive charge.
Structure of an Atom
• Ernest Rutherford
• 1911
• Learned physics in J.J.
Thomson’s laboratory in the late
1890s.
• Main area of interest was the
_______________particle (α
particle) - positively charged
particles with a mass
approximately 7500 times that of
an electron.
• Rutherford concluded that the plum
pudding model for the atom could not be
correct.
• The large deflections of the α particles
could be caused only by a center of
concentrated positive charge that would
repel the _______________ charged α
particles.
• Most of the α particles passed directly
through the foil because the atom is mostly
open space.
• Rutherford concluded that the plum pudding
model for the atom could not be correct.
• The large deflections of the α particles could
be caused only by a center of concentrated
positive charge that would repel the positively
charged α particles.
• Most of the α particles passed directly through
the foil because the atom is mostly open
space.
• By 1919, Rutherford concluded that the
nucleus of an atom contained what he called
_______________ (has the same magnitude
of charge as the electron, but its charge is
positive)
• Protons have a _______________charge and
the electron a charge of _______________
• 1932, he and a coworker (James Chadwick)
were able to show that most nuclei also
contain a neutral particle that they name the
_______________ (which has no charge)
• Mass and charge of the electron (e-), proton
(p+), and neutron (N)
The mass and charge of the electron, proton, and neutron.
Particle
Relative Mass*
Relative Charge
Electron
1
1Proton
1836
1+
Neutron
1839
None
*The electron is assigned a mass of 1 for comparison
Distinguishing Between Atoms
• Protons and electrons are equal in an atom of
an element (_______________).
• The _______________of an element is the
number of _______________ in the nucleus
of an atom of that element. (If the p+ and eare the same, then the atomic number will
also identify the number of e-)
• The sum of the number of neutrons and
the number of protons in a given
nucleus is called the _______________.
• _______________
• atoms with the same number of protons but
different numbers of _______________.
• Elements on the periodic table are the most
common _______________ of those
substances.
Distinguishing Between Atoms
• Isotopes
• Because they have different numbers of
neutrons, their mass numbers will be
different.
• Neon - 20
• Neon - 21
• Neon - 22
• All of these are isotopes of neon.
Distinguishing Between Atoms
• Isotopes
• 3 known isotopes of hydrogen
• hydrogen - 1
• hydrogen - 2
• hydrogen - 3
[hydrogen]
[deuterium]
[tritium]
Modern Day Atom
• _______________ – negatively charged
subatomic particle that moves around
the nuclear in different energy levels
and sublevels
• _______________ – positively charged
subatomic particle located in the
nucleus of an atom
• _______________ – neutral subatomic
particle located in the nucleus of an
atom
Atom Lab
Elements and Compounds
Elements
• Simplest forms of _______________
that can exist under normal laboratory
conditions.
• Cannot be separated into simpler
substances by
_______________means.
• Building blocks of other substances.
Compounds
• Two or more _______________
combined together.
• Can be separated into simpler
substances only by chemical means.
Chemical Symbols
• Shorthand representation of an element.
• The symbol may be the first or the first two
letters of the name of the element.
• Some symbols are representative of the Latin
or Greek names for the element.
• Represented by one, two, or, less often,
three letters.
• First letter is always capitalized.
• Second or third letter is always lower case.
Chemical Formulas
• Shorthand representation of a compound.
• The subscript of a formula represents the
proportions of the various elements in the
compound - the proportions are always the
same for any one compound.
• H2O = water
• CO2 = carbon dioxide
• CO = carbon monoxide
Chemical Reactions
• One or more substances changing into
new substances.
• Starting substances are the reactants.
• Arrow dividing the two indicate “to
form” or “yields”.
• Ending substances are the products.
• ______________  ______________
Chemical Property
• The ability of a substance to undergo a
_______________ reaction and to form new
_______________.
• Chemical properties are only observed when
a substance undergoes a chemical change.
• A chemical change always results in a
change in the chemical _______________
of the substances involved.
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Burning
Decompose
Rust
Explode
Corrode
Rot
Conservation of Mass
• Law of Conservation of Mass
• In any physical change or chemical
reaction, mass is neither created nor
destroyed; it is conserved.
• The mass of the reactants equals the mass
of the products.
Periodic Table of Elements
• Shows all the known elements and
gives a lot of information about each
element.
• Invaluable in chemistry!
Development of Periodic Table
• Elements in the
same group
generally have
similar chemical
properties.
• Properties are not
identical, however.
Development of Periodic Table
Dmitri Mendeleev
and Lothar Meyer
independently
came to the same
conclusion about
how elements
should be
grouped.
Development of the Periodic Table
Mendeleev, for instance, predicted the
discovery of germanium as an element with
an atomic weight between that of zinc and
arsenic, but with chemical properties similar
to those of silicon.
Dmitri Mendeleev
• First to officially organize the elements in an
organized manner in 1869.
• Organized the elements according to their
increasing atomic mass.
• Then he grouped them into columns and
rows according to physical and chemical
properties.
• Row – _______________
• Column - _______________
• Mendeleev had no idea what atoms
were made of or why they behaved as
they did.
• Nevertheless, he was able to put
together the periodic table almost as we
know it today--except that some
elements were missing, because they
were unknown in 1869.
Henry Moseley
• Rearranged the elements according to
their _______________.
• Arranging the elements in this manner
provided for a better fit of chemical and
physical properties and aligned those
elements that were discovered after
Mendeleev developed the original
periodic table.
Parts of the Periodic Table of
Elements
• _______________ – substances to the
left of the dark line
• _______________ – substances to the
right of the dark line
• _______________ – those elements
that border the line
Properties of Metal, Nonmetals,
and Metalloids
Metals versus Nonmetals
Differences between metals and nonmetals
tend to revolve around these properties.
Metals versus Nonmetals
• Metals tend to form _______________.
• Nonmetals tend to form _______________.
Metals
Tend to be
_______________,
_______________,
_______________,
and good
conductors of heat
and electricity.
Metals
• Compounds formed
between metals and
nonmetals tend to
be ionic.
• Metal oxides tend to
be basic.
Nonmetals
• Dull, brittle
substances that are
poor conductors of
heat and electricity.
• Tend to gain
electrons in
reactions with
metals to acquire
noble gas
configuration.
Nonmetals
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Dull in appearance
May be a gas, liquid, or solid
Not ductile
Not mallable
Poor conductors of electricity and heat
Nonmetals
• Substances
containing only
nonmetals are
_______________
compounds.
• Most nonmetal
oxides are acidic.
Metalloids
• Have some
characteristics of
metals, some of
nonmetals.
• For instance, silicon
looks shiny, but is
brittle and fairly poor
conductor.
Fireworks
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Potassium – combustible element that helps oxidize firework mixtures
Lithium – adds red color
Sodium – gold and yellow colors
Magnesium – bright white color
Calcium – deepens the colors of the other elements in the fireworks
Strontium – red color and stablizes other elements
Barium – green color and stablizes other elements
Titanium – produces the spark
Iron – produces sparks
Copper – blue color
Zinc – smoke clouds
Aluminum – silver and white sparks and flames – sparklers
Carbon – black powder
Phosphorus – fuel
Sulfur – fuel
Antimony – glitter effects
Groups of the Periodic Table
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Group 1 – _______________ metals
Group 2 – _______________metals
Group 11 – _______________ metals
Group 17 – _______________
Group 18 – _______________
Periodic Trends
Sizes of Atoms – Atomic Radius
The bonding atomic
radius is defined as
one-half of the
distance between
covalently bonded
nuclei.
Atomic Radius
Ionic Size
• _______________ is a charged particle.
• All atoms are neutral – the protons and
electrons are equal to one another.
• The only way an atom becomes a
charged particle is if it
_______________ or
_______________ electrons.
Ionic Size
• _______________ – positively charged
ions
• Lost electrons – more protons than
electrons
• Metals tend to lose electrons
• _______________ – negatively charged
ions
• Gained electrons – more electrons than
protons
• Nonmetals tend to gain electrons
Ionic Size - Cations
• Cations are
__________
_____ than
their parent
atoms.
• The outermost
electron is
removed and
repulsions are
reduced.
Ionic Size - Anions
• Anions are
__________
than their
parent atoms.
• Electrons are
added and
repulsions
are
increased.
• Ions increase in
size as you go
_____________
a column.
• Due to
increasing
value of the
energy levels.
Ionization Energy
• Amount of energy required to
_______________ an electron from the
ground state of a gaseous atom or ion.
• First ionization energy is that energy
required to remove first electron.
• Second ionization energy is that energy
required to remove second electron, etc.
• It requires more energy to remove each
successive electron.
• When all valence electrons have been
removed, the ionization energy takes a
quantum leap.
Trends in First Ionization Energies
• As one goes down
a
column,________
energy is required
to remove the first
electron.
• For atoms in the
same group, the
valence electrons
are farther from
the nucleus.
Trends in First Ionization Energies
• Generally, as
one goes
across a row,
it gets harder
to remove an
electron.