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CHEMISTRY!!!!

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Title: CHEMISTRY!!!!


1
CHEMISTRY!!!!
2
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
3
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

4
Counting the Pieces
  • Protons equal to atomic number
  • Neutrons Mass Number Atomic Number
  • Electrons In a neutral atom equal to atomic
    number

5
Symbols
  • Contain the symbol of the element, the mass
    number and the atomic number.

6
Symbols
  • Contain the symbol of the element, the mass
    number and the atomic number.

Mass number
X
Atomic number
7
Symbols
  • Find the
  • number of protons
  • number of neutrons
  • number of electrons
  • Atomic number
  • Mass Number

19
F
9
8
Symbols
  • Find the
  • number of protons
  • number of neutrons
  • number of electrons
  • Atomic number
  • Mass Number

80
Br
35
9
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

10
Symbols
  • if an element has 91 protons and 140 neutrons
    what is the
  • Atomic number
  • Mass number
  • number of electrons
  • Complete symbol

11
Symbols
  • if an element has 78 electrons and 117 neutrons
    what is the
  • Atomic number
  • Mass number
  • Number of protons
  • Complete symbol

12
What if Atoms Arent Neutral
  • Ions charged atoms resulting from the loss or
    gain of electrons

13
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
81
1-
Br
35
14
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
27
Al
3
13
15
Isotopes
  • Atoms of the same element can have different
    numbers of neutrons
  • Different mass numbers
  • Called isotopes

16
Naming Isotopes
  • We can also put the mass number after the name of
    the element.
  • carbon- 12
  • carbon -14
  • uranium-235

17
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

18
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

19
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20
Pure Substances
  • Cannot be physically separated
  • Every sample has the same characteristics and
    they can be used to identify a substance

21
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

22
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)

23
Mixtures
  • A blend of two or more kinds of matter, each
    which retains its own identity and properties

24
Homogeneous Mixtures
  • Have uniform composition
  • Also known as SOLUTIONS
  • Examples salt water, tea

25
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

26
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)

27
Suspensions
  • A heterogeneous mixture where the solid particles
    eventually settle out of solution
  • Examples
  • Muddy water
  • Mixtures of two solids
  • Paint

28
Properties of Matter
  • All pure substances have characteristic
    properties
  • Properties are used to distinguish between
    substances
  • Properties are also used to separate substances

29
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

30
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

31
Physical Changes
  • A Physical Change is a change in a substance that
    does not alter the substances identity
  • Examples
  • Grinding
  • Cutting
  • Melting
  • Boiling

32
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

33
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

34
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

35
Covalent Bonding in Water
36
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

37
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

38
Ionic Bonding in NaCl
39
Metallic Bonds
  • Metals share valence electrons between all atoms
  • Like a group of positive ions in a sea of
    electrons

40
Atomic Theory and Structure
41
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

42
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.

43
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.

44
Law of Conservation of Mass
  • The law of conservation of mass states that
    matter is neither created nor destroyed in
    chemical reactions

45
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.

46
Thomsons Experiment

-
Vacuum tube
Metal Disks
47
Thomsons Experiment

-
48
Thomsons Experiment

-
49
Thomsons Experiment

-
50
Thomsons Experiment

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

51
Thomsons Experiment

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

52
Thomsons Experiment

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

53
Thomsons Experiment

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

54
Thomsons Experiment
  • By adding an electric field

55
Thomsons Experiment

-
  • By adding an electric field

56
Thomsons Experiment

-
  • By adding an electric field

57
Thomsons Experiment

-
  • By adding an electric field

58
Thomsons Experiment

-
  • By adding an electric field

59
Thomsons Experiment

-
  • By adding an electric field

60
Thomsons Experiment

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

61
Plum Pudding Model
  • Proposed by JJ Thomson
  • Said the atom had a uniform positive charge in
    which the negatively charged electrons resided

62
Fluorescent Screen
Lead block
Uranium
Gold Foil
63
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.

64
What he expected
65
Because
66
He thought the mass was evenly distributed in the
atom
67
Since he thought the mass was evenly distributed
in the atom
68
What he got
69
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.

70
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71
The Bohr Ring Atom
n 4
n 3
n 2
n 1
72
Electron Cloud Theory
73
What are acids and bases?
  • ACIDS BASES
  • TASTE SOUR BITTER
  • FEEL STINGS SLIPPERY
  • REACTIONS YES / METAL
    NO / METALS
  • CONDUCTS ELECTROLYTE
    ELECTROLYTE
  • RELEASES H
    OH-

74
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
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