The Atom

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• Chapter
• 3
• The Atom

2
The Atom

• ____________ (450 B.C.) proposed that all matter
  is made up of tiny, indivisible particles.
  (atomos)
• 3-2

3
Laws

• Law of Conservation of Mass mass is neither
  ____________ during ordinary chemical rxns or
  ___________ changes.
• 3-3

4
Laws

• Law of Definite Proportions compounds contain
  the same ____________ in exactly the same
  _____________ by mass regardless of the _______
  of the sample or the __________ of the compound.
• 3-4

5
Laws

• Law of Multiple Proportions If two or more
  ________________ are composed of the same
  ____________, the _______ of the masses of the
  second element combined with a certain _________
  of the first element is always a ratio of
  ______________________.
• 3-5

6
Daltons Atomic Theory

• In 1808 ___________, an English schoolteacher,
  came up with an atomic theory to explain these
  laws. Many of the _________ of his theory still
  hold true today.
• 3-6

7
Daltons Atomic Theory

• Each ____________ is composed of atoms.
• Atoms of a given element are __________, and
  __________ than those of any other element.
• A given compound forms by ____________ of two
  or more different atoms, always in the same
  _______________________ of atoms.
• Atoms are neither ________________ in any
  chemical reaction, only _____________.
• 3-7

8
The Structure of the Atom

• ______ the smallest _________ of an element
  that ________ the chemical ________ of that
  element.
• 3-8

9
The Discovery of the Electron

• ___________ (1897) an English physicist who
  discovered ________ using his famous ___________
  experiment. He determined the _______________
  ratio.
• 3-9

10
The Discovery of the Electron
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The Discovery of the Electron

• __________ (1909) an American __________ who
  determined the charge of electrons using his
  famous _________ experiment. The mass of an e-
  is approximately ________ the mass of an atom.
• 3-11

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The Discovery of the Electron
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The Discovery of the Electron

• Based on these discoveries, two inferences were
  made
• Because atoms are ____________, they must contain
  a ________ charge to _________ the negative
  electrons.
• Because e- are so light in mass _________ to
  atoms, atoms must contain other _____________
  that account for most of its mass.
• 3-13

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Plum Pudding Atomic Model
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Discovery of the Nucleus

• 1911, Ernest ________ conducted experiments with
  _________ materials that released only __________
  charged alpha particles.
• 3-15

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Discovery of the Nucleus
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Discovery of the Nucleus

• Rutherford concluded atoms have a ________ core
  with a _______ charge.
• Rutherfords Atomic Model

18
Discovery of the Nucleus

• Rutherfords student, _________, came up with a
  way to explain the location of e- in the atom

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Discovery of the NucleusThe electron cloud is
the current accepted model of the atom.
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The Atom

• Except for H, all ____________ contain
  _____________________.
• A proton has a charge ____________
  _____________to the neg. charged e-.
• Atoms contain _______________ of p and e-.
• Neutrons are _____________ neutral.
• P and no have almost ____________ masses,
  electrons weigh 1836 times ______. 3-20

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The Atom

• ______________ short range p to p, p to no
  and no to no forces hold the nuclear particles
  together.
• ___________________ (Z) the number of protons
  in each atom of a particular element.
• ?The atomic number _________ the element!
• 3-21

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Isotopes

• __________ atoms of the same element that have
  _______________ due to different numbers of
  __________.
• _____________ the total number of _______ and
  _________ that make up the nucleus of an isotope
• Isotopes are written with the _____________
  written after the element name or symbol with a
  _______ ex. Uranium-235 or U-235
• 3-22

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Isotopes

• Uranium-235 or U-235
• Mass number atomic number number of ________
• 235 (protons neutrons) 92 protons 143
  neutrons
• This info could also be portrayed using a
  _____________
• 235U
• 92

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Isotopes

• In nature, __________ are almost always found
  as a ___________ of isotopes
• Isotopes have ________________ chemical
  properties
• Isotopes with _______ neutrons have a higher
  mass and are often described as _______.
  3-24

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Isotopes

• Nuclide a general term for a _________
• __________ of an element.

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Atomic Mass

• Atomic Mass Unit (____) one amu is exactly
  _____ of the mass of a ________ atom.
• _______________ the weighted average of the
  atomic masses of the _________________ isotopes
  of an element.
• 3-26

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Calculating the Average
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Moles

• _____ the amount of a substance that contains
  as many _______ as there are atoms in exactly 12g
  of ___________.

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Moles

• _____________ the number of particles in
  exactly one ______ of a pure substance
  6.02214179 x 1023 (well use __________)

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Moles

• 602,000,000,000,000,000,000,000
• If you had 6.02 x 1023 pennies and gave away 1
  million a day to every person on earth, it would
  take you 3000 years to distribute all your
  money!!
• 3-30

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Molar Mass

• ____________ the mass of one mole of a pure
  substance.
• the mass of _________ atoms or __________ is
  measured in _____. The mass of a mole of the
  same substance is _____________ the same, with
  the units _______.
• Ex. H20 H x 2 1.01 x 2 2.02
• O x 1 16.00 x 1 16.00
• 18.02
• 3-31

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Molar Mass
1) What is the molar mass of BaCl2? 2) What is
the molar mass of NaI? 1) Ba _ x _____ g/mol
_______ Cl _ x _____ g/mol
______ _______ g/mol 2) Na _ x
______ g/mol ______ I _ x
_______ g/mol _______ ________
g/mol 3-31
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Molar Mass

• This photograph shows one mole of _______ (NaCl
  58.44g/mol), ____ (H2O 18.02 g/mol), and ____(N2
  28.02 g/mol).
• 3-33

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Mass/Mole Conversions

• When given the number of _______, you can find
  the _______by
• Moles x _g__ grams
• mole
• Ex. 5.0 moles of H2O X g
• 5.0 moles x 18.02g 90. g H2O in 5.0
  mol moles
• 3-34

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Mass/Mole Conversions

• Moles x _g_ moles
• mol
• Now try these problems
• 3) 8.32 moles of barium chloride equals how many
  grams?
• 4) 20.1 moles of sulfur dioxide equals how many
  grams?
• 3-35

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Mass/Mole Conversions

• 3) 8.32 moles of barium chloride equals how many
  grams?
• 8.32 moles BaCl2 x _____ g/mol _____ grams
• BaCl2
• 4) 20.1 moles of sulfur dioxide equals how many
  grams?
• 20.1 moles SO2 x ______ g/mol _____ g SO2
• 3-36

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Mass/Mole Conversions

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Mass/Mole Conversions

• When given the amount in _______, you can
  calculate the number of ______ by
• g x mol moles
• g
• Ex. 11.2 g NaCl X moles
• ___ g NaCl x 1.0 mol NaCl _____ mols NaCl
• 58.44g
• 3-38

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Mass/Mole Conversions
g x mol moles g Now try these
problems 5) 50.56 g of sodium chloride equals
how many moles? 6) 329.8 g of ammonia equals how
many moles? 3-39
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Mass/Mole Conversions
5) 50.56 g of sodium chloride equals how many
moles? _______ g NaCl x mole _____ moles
NaCl _____g 6) 329.8 g of
ammonia equals how many moles? _____ g NH3 x mole
_____ moles NH3 ______g 3-40
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Particle/Mole Conversions

• You can also calculate between _______ and number
  of ________
• (1.0 moles 6.02 x 1023 particles)
• To enter this number into your calculator, punch
  in 6.02 _____ button (________) 23.
• 3-41

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Particle/Mole Conversions

• Ex. 2.59 moles of marble (CaCO3) contains how
  many molecules?
• _____ mol CaCO3 x 6.02 x 1023 molecules
  ___________ 1.0 mol CaCO3
  molecules
• Particles can be molecules, atoms or formula
  units
• 7) How many molecules are in 5.0 moles of carbon
  dioxide?
• 5.0 mol CO2 x ________ molecules
• 1.0
  mole CO2
• __________ molecules CO2
• 3-42

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Particle/Mass Conversions

• Ex. What is the mass of 3.25 x1023 molecules of
  nitrogen?
• 3.25 x1023 N2 x ______ g _____g N2
• 6.02 x 1023
• 8) How many molecules are 57.36 g of NaCl?
• 57.36 g NaCl x__________ __________
• ____ g molecules
• 3-43

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• The
• End!