Elements are made of atoms = the smallest particle that has all the characteristics of the element

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Elements are made of atoms the smallest
particle that has all the characteristics of the
element
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How Small is an Atom?

• A copper penny contains 2.4 x 1022 atoms
• Earths population is approx. 7 x 109
• A scanning tunneling microscope makes it possible
  to see individual atoms
• TED

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Scanning Tunneling Microscope
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Atom Image
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Subatomic Particles

• Mass of atom is generally protons neutrons,
  majority of mass is in nucleus
• Mass of proton 1
• Mass of neutron 1
• Mass of electron 1/2000
• (mass of H proton 1 is standard)

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Subatomic Particles
Subatomic Particle Charge Location
Proton
Neutron
Electron
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Atoms are neutral

• Why?

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Distinguishing Between Atoms
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Atomic Number (Z)

• Found on the periodic table
• Is equal to the number of protons
• Each element has its own atomic
• protons electrons

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Average Atomic Mass

• Also found on the periodic table
• Is the average mass of all of the atoms of that
  element
• Mass number (A) actual mass of one atom
• Mass number protons neutrons

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Carbon-12?

• When written in this format
• 12 is the mass

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Practice with a Partner
Atom Symbol Atomic Aver Atomic Mass Mass protons neutrons electrons
Lithium 7
Boron 9
Carbon 12
Nitrogen 14
Oxygen 16
Helium 4
Sodium 23
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Isotopes

• Atoms of the same element that have different
  masses
• Have different masses because they have different
  numbers of neutrons
• protons always the same

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Example

• Carbon isotopes
• Carbon-12
• Carbon-13
• Carbon-14
• Might also be written C-12, C-13, C-14
• Or

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Nuclear Formulas

• Used to write isotopes

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Isotopes

• How are isotopes similar?
• How do they differ?
• Isotopes are chemically alike b/c they have
  identical numbers of protons electrons

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Average Atomic Mass

• How is it calculated?
• Based on the relative abundance of the naturally
  occurring isotopes of the element
• Each isotope has a fixed mass and a natural
  abundance

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Question

• With the following information, calculate the
  average atomic mass of chlorine
• 76 of chlorine isotopes found naturally have a
  mass of 35
• 24 of chlorine isotopes found naturally have a
  mass of 37

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How did you find the answer?
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PROJECT
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Warm Up 1/15/2014

• P. 85 2-3
• P. 87 6-9
• Calculate average atomic mass given the following
  information
• Carbon-12 is found naturally 98.89 of the time
• Carbon-13 is found naturally 1.11 of the time

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Warm Up 1/16/2014

• Write the procedure for determining average
  atomic mass (paragraph format, complete
  sentences).
• Quiz tomorrowcumulative
• Homework tonight

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Atomic Theories

• Democritus
• John Dalton
• JJ Thomson
• Ernest Rutherford
• Niels Bohr
• Schrodinger

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Atom Democritus

• 400 BC
• Called natures basic particle an atom
• Atom (Greek) means uncuttable or indivisible
• No experimental evidence

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Daltons Atomic Theory (1808)

• All matter is composed of tiny indivisible
  particles called atoms
• Atoms of the same element are identical
• Atoms of different elements can physically mix
  together or can chemically combine with one
  another in simple whole number ratios to form
  compounds
• Chemical reactions occur when atoms (in
  compounds) are separated, joined, or rearranged

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Daltons Atomic Theory

• Much of Daltons theory is accepted except ?
• Except that atoms are indivisible AND that all
  atoms of an element are identical

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Thomson Plum Pudding Model

• 1897
• Discovered the electron
• His model proposed that negatively charged
  particles were randomly distributed within a
  pudding of positively charged particles

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Rutherford The Gold Foil

• 1909
• Discovered the atoms nucleus
• He bombarded a thin, gold foil with fast moving
  alpha particles (p 72-73)

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Rutherford The Gold Foil

• A small amount of particles were deflected by the
  tiny nucleus most of the particles passed on
  through
• He concluded the volume of the atom was mostly
  empty space

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Bohrs Atomic Model

• 1915
• Electrons organized in energy levels or shells
  around a nucleus of protons and neutrons
• A planetary modelnot entirely correct

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The Electron Cloud Schrodinger

• Is a probability model
• Describes a cloud like region where the electron
  is likely to be
• Based on mathematical equation

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Project Time
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A Closer Lookthe Bohr Model

• Video

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Bohrs Model of the Atom

• Scientists found that when an electric current is
  passed through a glass tube that contains
  hydrogen gas, the tube emits light
• When this light is passed through a prism, four
  narrow bands of bright light are observed against
  a black background
• This is hydrogens line emission spectrum
• Bands are at specific wavelengths, which are
  unique to each element

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Niels Bohr

• Niels Bohr proposed a model for the hydrogen atom
  that explained the spectrum of the hydrogen atom.
  
• The Bohr model was based on the following
  assumptions

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Bohrs Model of the Hydrogen Atom

• Electrons are arranged in concentric circular
  paths or orbits around the nucleus
• Electrons in a particular path have a fixed
  energy
• The energy of the electron in an orbit is
  proportional to its distance from the nucleus.
  The further the electron is from the nucleus, the
  more energy it has.
• An electron can either gain or lose energy inside
  this orbit, electrons can move up or down to
  another orbit

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Continued

• A quantum of energy is the amount of energy
  required to move an electron from its present
  energy level to the next higher one
• Light is absorbed when an electron jumps to a
  higher energy orbit and emitted when an electron
  falls into a lower energy orbit

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Continued

• The energy of the light emitted or absorbed is
  exactly equal to the difference between the
  energies of the orbits
• The energy given off is electromagnetic radiation
• Is given off as photons (particle of light with
  no mass)

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Continued

• Lowest energy state of atom ground state
• Higher energy state of atom excited state
• Neon signsexcited neon atoms emit light when
  falling back to the ground state

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Project Time

• ReminderQuiz tomorrow

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Warm Up 1/17/2014

• How did Bohrs model of the atom differ from
  Schrodingers?

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Modern Atomic Theory
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Electron Cloud Model

• AKA quantum mechanical model
• Clouds of probability where electrons are most
  likely to be
• Electrons are located in orbitals (not orbits)

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Electron Cloud Model

• 4 types of orbitals s, p, d, f
• Each orbital can only hold 2 electrons

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Warm Up 1/21/2014

• Construct a table to compare subatomic particles.

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Warm Up 1/24/2014

• Create a Venn diagram to compare the Bohr model
  to the electron cloud model.
• Homework DUE
• Quiz today

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Warm Up 1/27/2014

• Given an isotope for fluorine, fluorine-19
• What is Z?
• What is A?

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Quizzes

• Dropped one question
• 2nd block 84
• 3rd block 86

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What are ions?Why would ions form?

• Atoms with a charge
• When they gain, lose, or share electrons
• Butwhy would they do this?

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What is the Octet Rule?

• Says that atoms tend to gain, lose or share
  electrons so as to have eight electrons in their
  outer electron shell
• More specifically, the number of electrons needed
  to fill the s and p sublevels of that energy level

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Practice
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Nuclear Chemistry
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How Atoms Combine

• Section 3.2

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Chemical Properties

• Chemical properties how reactive an atom is
• Does it like to combine with other atoms or is it
  stable alone?
• Which groups on the periodic table are reactive?
• Which groups are stable?

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Compounds

• A substance that is composed of atoms of 2 or
  more different elements that are chemically
  combined
• Example NaCl
• Why do these two atoms like to combine?
• (draw)

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Types of Bonds

• Ionic bondswhen atoms lose or gain electrons
• Example _____________
• Covalent bondswhen atoms share electrons
• Example ______________
• (draw)

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Compounds

• Atoms want their outer energy level filled with
  electrons, in most cases this is 8 electrons
• Which groups on the periodic table would you
  predict would commonly form bonds together?
• Class Bonding Activity

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Warm Up8/30/12

• Complete Section Assessment 3.1
• 1-5 on page 59

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Group Assignment

• Chemical Reactivity worksheet

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Independent Notebook Assignment

• Vocabulary section 3.2 (page 60)

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Independent Assignment

• Create a posterto display a large drawing of an
  atomthe element will be assigned to you.
• Format see example
• Grading based on neatness accuracy.

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Element Assignment

• H
• He
• Li
• Be
• B
• C
• N
• O
• F
• Ne
• Na
• Mg
• Al
• Si
• P
• S
• Cl
• Ar

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Warm Up8/31/12

• What group is chlorine in?
• What is its symbol?
• List everything that you can learn about chlorine
  based its location in the periodic table.
  Include what other elements it might bond with.

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Agenda

• Quiz
• Project Presentations