CHEMISTRY!!!!

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CHEMISTRY!!!!
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Subatomic particles
Actual mass (g)
Relative mass
Name
Symbol
Charge
Electron
e-
-1
1/1840
9.11 x 10-28
Proton
p
1
1
1.67 x 10-24
Neutron
n0
0
1
1.67 x 10-24
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Counting the Pieces

• Atomic Number number of protons in the nucleus
• of protons determines kind of atom (since all
  protons are alike!)
• the same as the number of electrons in the
  neutral atom.
• Mass Number the number of protons neutrons.
• These account for most of mass

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Counting the Pieces

• Protons equal to atomic number
• Neutrons Mass Number Atomic Number
• Electrons In a neutral atom equal to atomic
  number

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Symbols

• Contain the symbol of the element, the mass
  number and the atomic number.

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Symbols

• Contain the symbol of the element, the mass
  number and the atomic number.

Mass number
X
Atomic number
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Symbols

• Find the
• number of protons
• number of neutrons
• number of electrons
• Atomic number
• Mass Number

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F
9
8
Symbols

• Find the
• number of protons
• number of neutrons
• number of electrons
• Atomic number
• Mass Number

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Br
35
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Symbols

• if an element has an atomic number of 34 and a
  mass number of 78 what is the
• number of protons
• number of neutrons
• number of electrons
• Complete symbol

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Symbols

• if an element has 91 protons and 140 neutrons
  what is the
• Atomic number
• Mass number
• number of electrons
• Complete symbol

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Symbols

• if an element has 78 electrons and 117 neutrons
  what is the
• Atomic number
• Mass number
• Number of protons
• Complete symbol

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What if Atoms Arent Neutral

• Ions charged atoms resulting from the loss or
  gain of electrons

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What if Atoms Arent Neutral

• Anion negatively charged ion result from
  gaining electrons
• Take the number of electrons in a neutral atom
  and add the absolute value of the charge

Identify Number of Protons Number of
Neutrons Number of Electrons
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1-
Br
35
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What if Atoms Arent Neutral

• Cation positively charged ion result from the
  loss of electrons
• Take the number of electrons in a neutral atom
  and subtract the value of the charge

Identify Number of Protons Number of
Neutrons Number of Electrons
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Al
3
13
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Isotopes

• Atoms of the same element can have different
  numbers of neutrons
• Different mass numbers
• Called isotopes

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Naming Isotopes

• We can also put the mass number after the name of
  the element.
• carbon- 12
• carbon -14
• uranium-235

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Atomic Mass

• How heavy is an atom of oxygen?
• There are different kinds of oxygen atoms
• We are more concerned with average atomic mass
• Average atomic mass is based on abundance of each
  element in nature.
• We dont use grams because the numbers would be
  too small

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Measuring Atomic Mass

• Unit is the Atomic Mass Unit (amu)
• It is one twelfth the mass of a carbon-12 atom
• Each isotope has its own atomic mass, thus we
  determine the average from percent abundance

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Pure Substances

• Cannot be physically separated
• Every sample has the same characteristics and
  they can be used to identify a substance

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Elements

• Are made up of ONE type of atom
• Atoms are the smallest unit of an element that
  maintains the chemical identity of that element
• They can be found on the Periodic Table
• Examples Carbon, Nitrogen, Calcium

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Compounds

• Can be broken down into simple stable substances
• Are made up of two or more types of atoms that
  are chemically bonded
• Examples Water (H2O), sugar (C12H22O11)

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Mixtures

• A blend of two or more kinds of matter, each
  which retains its own identity and properties

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Homogeneous Mixtures

• Have uniform composition
• Also known as SOLUTIONS
• Examples salt water, tea

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Solutions

• ALLOYS are solid solutions that contain at least
  1 metal
• They are blended together so that they have more
  desirable properties
• Some alloys you may know are
• Stainless Steel iron, chromium, and zinc
• Brass zinc and copper
• Bronze tin and copper
• Sterling Silver copper and silver

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Heterogeneous Mixtures

• Do not have uniform composition
• You can see the particles in them
• Examples
• Sand on the beach (contains sand, shells, rocks,
  bugs, etc)
• Soil (contains dirt, rocks, worms, etc)
• Chicken Soup (contains water, chicken, veggies
  etc)

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Suspensions

• A heterogeneous mixture where the solid particles
  eventually settle out of solution
• Examples
• Muddy water
• Mixtures of two solids
• Paint

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Properties of Matter

• All pure substances have characteristic
  properties
• Properties are used to distinguish between
  substances
• Properties are also used to separate substances

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Physical Properties

• A Physical Property is a characteristic that can
  be observed or measured without changing the
  composition of the substance
• Physical properties describe the substance itself
• Examples
• Physical State
• Color
• Mass, shape, length
• Magnetic properties

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Chemical Properties

• A Chemical Property indicates how a substance
  will react with another
• Chemical properties cannot be determined without
  changing the identity of the substance
• Examples
• Iron Rusting
• Silver Tarnishing

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Physical Changes

• A Physical Change is a change in a substance that
  does not alter the substances identity
• Examples
• Grinding
• Cutting
• Melting
• Boiling

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Chemical Changes

• A change in which one or more substances are
  converted into different substances is called a
  Chemical Change
• Signs of a Chemical Change
• Color Change
• Gas is Released
• Temperature Change
• Precipitate Solid falls out of solution
• Substance Disappears

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How Atoms Combine

• Two or more atoms that are chemically combined
  make up a compound
• The combination results in a chemical bond, a
  force which holds elements together in a compound

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Covalent Bonds

• Covalent Bonds are formed when atoms in a
  compound share electrons
• Molecule two or more atoms held together by a
  covalent bond
• Usually occurs between nonmetals

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Covalent Bonding in Water
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Ions

• An atom that has gained or lost an electron is
  called an ion.
• Multiple atoms can combine to form an ion
  called a Polyatomic Ion
• Silicate (SiO44-) and Carbonate (CO32-) are
  important in forming materials at Earths Surface

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Ionic Bonding

• Positive and negative ions attract each other
• Ionic Bonds occur when oppositely charged ions
  form a compound
• Usually consist of 1 metal and 1 nonmetal
• Positive ion written first in chemical formula
  (NaCl)
• Ionic compounds have a neutral charge

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Ionic Bonding in NaCl
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Metallic Bonds

• Metals share valence electrons between all atoms
• Like a group of positive ions in a sea of
  electrons

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Atomic Theory and Structure
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Democritus

• Democritus added
• Matter is composed of atoms which move through
  empty space
• Atoms are solid, homogeneous, indestructible, and
  indivisible
• Different atoms have different shapes and sizes
• The size, shape, and movement of atoms determine
  their properties

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Leading to the modern theory

• Late 1700s - John Dalton- England.
• Teacher- summarized results of his experiments
  and those of others.
• Daltons Atomic Theory
• Combined ideas of elements with that of atoms.
• Saw atoms as small solid spheres. Billiard Ball
  Model.

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Daltons Atomic Theory

• All matter is made of tiny indivisible particles
  called atoms.
• Atoms of the same element are identical, those of
  atoms of different elements are different.
• Atoms of different elements combine in whole
  number ratios to form compounds.
• Chemical reactions involve the rearrangement of
  atoms. No new atoms are created or destroyed.

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Law of Conservation of Mass

• The law of conservation of mass states that
  matter is neither created nor destroyed in
  chemical reactions

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Discovery of the Electron

• J. J. Thomson - English physicist. 1897
• Made a piece of equipment called a cathode ray
  tube.
• It is a vacuum tube - all the air has been pumped
  out.

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Thomsons Experiment

-
Vacuum tube
Metal Disks
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Thomsons Experiment

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Thomsons Experiment

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Thomsons Experiment

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Thomsons Experiment

-

• Passing an electric current makes a beam appear
  to move from the negative to the positive end

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Thomsons Experiment

-

• Passing an electric current makes a beam appear
  to move from the negative to the positive end

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Thomsons Experiment

-

• Passing an electric current makes a beam appear
  to move from the negative to the positive end

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Thomsons Experiment

-

• Passing an electric current makes a beam appear
  to move from the negative to the positive end

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Thomsons Experiment

• By adding an electric field

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Thomsons Experiment

-

• By adding an electric field

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Thomsons Experiment

-

• By adding an electric field

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Thomsons Experiment

-

• By adding an electric field

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Thomsons Experiment

-

• By adding an electric field

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Thomsons Experiment

-

• By adding an electric field

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Thomsons Experiment

-

• By adding an electric field he found that the
  moving pieces were negative

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Plum Pudding Model

• Proposed by JJ Thomson
• Said the atom had a uniform positive charge in
  which the negatively charged electrons resided

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Fluorescent Screen
Lead block
Uranium
Gold Foil
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He Expected

• The alpha particles to pass through without
  changing direction very much.
• Because?
• the positive charges were thought to be spread
  out evenly. Alone they were not enough to stop
  the alpha particles.

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What he expected
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Because
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He thought the mass was evenly distributed in the
atom
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Since he thought the mass was evenly distributed
in the atom
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What he got
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How he explained it

• Atom is mostly empty.
• Small dense, positive piece
• at center.
• Alpha particles are deflected by it if
  they get close enough.

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The Bohr Ring Atom
n 4
n 3
n 2
n 1
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Electron Cloud Theory
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What are acids and bases?

• ACIDS BASES
• TASTE SOUR BITTER
• FEEL STINGS SLIPPERY
• REACTIONS YES / METAL
  NO / METALS
• CONDUCTS ELECTROLYTE
  ELECTROLYTE
• RELEASES H
  OH-

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HOW DO WE MEASURE ACIDS AND BASES?

• INDICATORS
• A SUBSTANCE THAT TURNS ONE COLOR IN AN ACIDIC
  SOLUTION AND ANOTHER COLOR IN A BASIC SOLUTION
• SOME INDICATORS ARE
• LITMUS DYE THAT COMES FROM A LICHEN
• PHENOLPHTHALEIN INDICATES ONLY BASES
• UNIVERSAL INDICATOR
• ACID, NEUTRALS, BASES
• CABBAGE JUICE
• ACIDS, NEUTRAL, BASE