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Atomic Structure

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Title: A Guided Tour of the Periodic Table Author: FREDA Last modified by: Erin Created Date: 10/23/2018 3:58:52 PM Document presentation format – PowerPoint PPT presentation

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Title: Atomic Structure


1
  • Atomic Structure

3.1
2
Atomic History
  • In 400 BC a Greek Philosopher named Democritus
    suggested the universe was made of invisible
    units called atoms.

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1800s John Daltons Theory (Still Accepted)
  1. Every element is made of tiny, unique particles
    called atoms
  2. Atoms of different elements can join to form
    molecules.

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John Daltons Theory- Disproved
  1. Atoms are the smallest particles and cannot be
    subdivided.
  2. Atoms of the same element are exactly alike in
    mass

7
JJ Thomson
  • Credited with discovering negative charged
    particles called electrons.

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Rutherford
  • Credited with discovering the nucleus.
  • Also concluded that atoms are mostly empty space.

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Further Research Finding
  • Later on, the discovery of protons and neutrons
    were discovered in the nucleus.
  • And it was later concluded that all atoms are
    neutral in charge.
  • The number of protons and electrons in any atom
    are always equal.

15
Niels Bohr
  • Suggested that electrons move around atoms in set
    paths around the nucleus.
  • He said each path is an energy level

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Todays Theory
  • It has been determined that it is impossible to
    pinpoint an electrons exact position due to its
    tremendous speed.
  • Electrons do not move around in definite paths.

20
Todays Theory
  • Electrons are found in orbitals within energy
    levels. (s, p, d, and f )
  • a region in an atom where there is a high
    probability of finding electrons.

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Todays Theory
  • Electrons are now viewed as waves vibrating on a
    string rather than simple particles.
  • Wave-Particle Duality Theory

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What are atoms?
  • The smallest part of an element that still has
    the elements properties.

25
Parts of an atom
  • Nucleus
  • Proton
  • Neutron
  • Electron

Subatomic particles
26
Nucleus
  • center of an atom
  • positively charged
  • makes up 99.9 of the atoms mass
  • contains protons and neutrons

27
Protons
  • Charge ()
  • Mass is equal to 1 atomic mass unit (amu)
  • Found in the nucleus
  • Identifies the element/atom

28
Neutrons
  • Charge (0) neutral
  • Mass is equal to 1amu
  • Found in the nucleus
  • Helps determine mass

29
Electrons
  • Charge is negative (-)
  • Mass is equal to 0 amu
  • Found outside the nucleus, in the electron cloud

30
Energy levels
  • 1st level holds up to 2 e-
  • 2nd level holds up to 8 e-
  • 3rd level holds up to 8 or 18 e-
  • 4th level holds up to 8, 18, or 32 e-
  • Outer Level holds up to 8 e-
  • (called valence electrons)

31
Valence Electron
  • The number of electrons in the outermost electron
    shell.
  • Most important

32
A Guided Tour of the Periodic Table
  • 3.2

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Periodic Law
  • Properties of elements tend to change in a
    regular pattern when elements are arranged in
    order of increasing atomic number.

35
Periodic Law
  • Periodic Table is set up by increasing atomic
    number.
  • Atomic Number is the of protons in the atom.

36
Average Atomic Mass
37
Atomic Number
  • tells you number of protons
  • Never Changes for an atom.
  • Appears as a whole on the periodic table.
  • No two elements can have same atomic .

38
Atomic Number
Atomic Number
of protons
39
Mass Number
  • The mass of an atom
  • Total number of protons plus neutrons in the
    nucleus of a single atom.
  • Atoms of the same element wont always have the
    same mass number

40
Mass Number
of neutrons
Mass
of protons
41
Isotopes
  • Any atoms having the same number of protons but
    different number of neutrons.
  • So they also have different mass numbers.

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Average Atomic Mass
  • Average mass of all known isotopes for an element
  • Found on the periodic table as a number with a
    decimal

44
Atoms Charge
  • They are neutral.
  • All atoms have the same number of protons and
    electrons.
  • Charges cancel each other out.

45
Ions
  • Charged particles.
  • Form when atoms lose or gain electrons.
  • They do this so the ions have a full outer shell
  • Two Types.

46
Cations
  • Positively charged ions.
  • Form when atoms lose electrons.
  • Metals
  • Left side of table

47
Cations
  • of protons greater than of electrons
  • More () than (-)

48
Na Atom
Na Cation
49
Anions
  • Negatively charged ions.
  • Form when atoms gain electrons.
  • Nonmetals
  • Right side of table

50
Anions
  • of protons less than of electrons
  • More (-) than ()

51
Cl- Anion
Cl atom
52
Quantifying atoms or ions
1
Protons 3 Neutrons 7-3 4 Electrons
3 Electrons 3 -1 2
53
Families of Elements
  • 3.3

54
Periodic Table
  • Periods
  • -a horizontal row of elements.
  • -Tells you the electrons energy level.

55
Periodic Table
  • Groups (families)
  • -a vertical column of elements.
  • -Tells us the of valence electrons and the
    elements chemical properties.

56
Types of Elements
  1. Metals
  2. Nonmetals
  3. Semiconductors/metalloids

57
Alkali Metals
Nobel Gases
Non Metals
Alkaline Earth Metals
Metalloids
Halogens
Other Metals
Transition Metals
Inner Transition Metals
58
Alkali Metals Group 1
  • Most reactive metals
  • one valence e-
  • Found as compounds (salts) and not elements due
    to reactivity.
  • As elements they are soft metals and good
    conductors.

59
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Alkaline-earth Metals Group 2
  • Less reactive than Alkali
  • They are also more commonly found as compounds
  • 2 most common are Ca and Mg.

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Transition Metals Groups 3-12
  • Less reactive than groups 1 and 2
  • Good conductors

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Transition Metals
  • All solids with the exception of mercury
  • Valuable metals (Ag, Au, Pt, Cu,
    Ni, Fe, Co)

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Non Metals
  • Are not able to conduct electricity or heat very
    well.
  • Found in groups 13-18, with the exception of
    hydrogen

68
Carbon
  • Found as an element (coal, diamond, graphite)
  • Found in millions of different compounds
  • Called Organic Compounds

69
HYDROGEN
  • It is a gas/nonmetal
  • A very explosive gas.
  • It is located in group one because it has one
    valence electron
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    2773657669qhindenburghlen

70
Oxygen and Nitrogen
  • Oxygen is the most common element found on Earth
  • Nitrogen most common gas found in the atmosphere

71
Halogens Group 17
  • Most reactive nonmetals
  • Form salts with group 1
  • Used to kill bacteria
  • Bromine only liquid nonmetal

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Noble Gases Group 18
  • Stable and not reactive. (inert)
  • Dont form compounds.
  • They have a full valence shell.

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Metalloids (Semiconductors)
  • 7 elements on the step
  • Properties of both metals and non-metals.
  • Silicon the most familiar (computer chips)

76
Inner Transition Metals
  • Two rows at the bottom
  • Some are Radioactive ex. Uranium
  • 93 and greater are all manmade

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Moles
  • 3.4

79
Counting Units
  • We buy things by the dozen.
  • One dozen 12 items
  • We use the unit mole to count things in chemistry

80
Moles
  • the SI base unit that describes the amount of a
    substance.

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Avogadros Constant
  • Represents the number of particles in one mole of
    a substance.
  • The number is 6.02 x 1023 particles, atoms, or
    molecules

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Moles
  • Used for counting with really tiny atoms
  • One mole represents the atomic mass of an
    element.

85
Molar Mass
  • The mass in grams of 1 mol of a substance.
  • Using the periodic chart you can determine the
    molar mass of any element or compound.

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Molar Mass Example
  • So how many grams in two moles of Ca?

88
Solution
  • The molar mass of Ca is 40 g/mol.
  • 2 moles x 40 grams 80 g
  • 1 mole

89
Mole Problems
  • You can determine how many moles of a substance
    you have if you know the mass of the substance.

90
Example Problem
  • If you have 92 grams of Na how many moles would
    you have?

91
Solution
  • MM of Na is 23 g/mole
  • 92 g x 1 mole 4.0 moles
  • 23 g
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