Chapter 9, Part 1: Inorganic Analysis

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Chapter 9, Part 1Inorganic Analysis
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Learning About Matter

• Element vs Atom
• Compound vs Molecule
• Gas vs Liquid vs Solid
• Homogeneous vs Heterogeneous Mixture
• Matter must be understood on three levels
• Macroscopic water is a colorless liquid
• Symbolic H2O(l)
• Atomic

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What is an Element?

• Pure substance that cannot be broken down into
  simpler substances
• Large collection of one type of particle
• Represented by a 1-2 letter symbol of the
  elements name first letter capitalized
• May exist as a solid, liquid or gas
• May exist in aggregates of 2 or more atoms
• May be reactive or unreactive

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Examples and Nonexamples of Elements
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What is an Atom?

• The smallest unit of an element that retains the
  microscopic properties of the element.
• It can exist alone or be combined.
• It may be in any physical state.
• An atom can be represented by a sphere or other
  geometric figure.

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Particulate Model of Matter

• Atoms are often represented by spheres
• Atoms of the same element have the same shape,
  color and size
• When atoms combine the spheres are attached to
  each other
• The number of spheres of each element represents
  the proportion of the element in the substance

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Pure Substances

• Element substance with one type of atom
• Compound substance with a specific ratio of two
  or more types of atoms
• Molecule smallest unit of an compound that
  retains its microscopic properties

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Element or Compound?
C2H5O
Na
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Solids, Liquids and Gases

• solid - particles are not moving freely and are
  closely and neatly packed
• liquid - particles are moving freely in part of
  the container and are somewhat close to each
  other
• gas - particles are moving freely and are far
  apart

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Liquid, Gas or Solid?
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Mixtures

• Homogeneous uniform distribution of all
  particles of 2 or more substance but has variable
  composition (example coffee)
• Heterogeneous non-uniform distribution but still
  has variable composition (example fresh milk)

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Homogeneous or Heterogeneous?
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Classification of Matter
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The Periodic Table
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The Periodic Table

• Created by Mendeleev in 1869.
• He organized the known elements into families
  according to similarities in their chemical
  physical properties.
• When a gap seemed to appear he assumed it was an
  undiscovered element.
• He used the properties of the adjacent elements
  to predict the properties of missing elements.

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Cells in the Periodic Table

• 11
• Na
• 22.99

Atomic Number
Element Symbol
Atomic Mass
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Periodic Table Facts

• Fill in the blank outline of the periodic table
  with the following periodic table facts
• Group (1-18) and Periods (1-7)
• Representative and Transition elements
• Lanthanides and Actinides
• Metals, Nonmetals and Metaloids
• Alkali and Alkaline Earth elements
• Halogens and Noble Gases
• Solid, Liquids and Gaseous elements

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Periodic Table Facts
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Periodic Table Facts
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Metals and Nonmetals

• Metals
• Shiny, ductile
• Good conductors of heat and electricity
• Nonmetals
• Dull and brittle
• Poor conductors, good insulators

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Other Classifications of Elements

• Liquids Hg and Br
• Gases H, O, N, F, Cl, Group 18
• Diatomic H2, N2, O2, F2, Cl2, Br2, I2

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Learning Check

• Which element is at the intersection of Period 5
  and Group 10? Is it a metal, non-metal or
  metalloid? Is it a solid, liquid or gaseous
  element?

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The Nuclear Atom
nucleus
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Subatomic Particles
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Atomic Symbols
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Isotopes

• Atoms with the same number of protons, but
  different numbers of neutrons.
• Example Isotopes of chlorine
• 35Cl 37Cl
• chlorine - 35 chlorine -
  37
• p 17, n 18 p 17, n 20

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Number of Electrons

• An atom is neutral and the net charge is zero
• Number of protons Number of electrons
• Atomic number Number of electrons
• If protons ? electrons then a right superscript
  shows the sign and magnitude of the charge

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Subatomic Particles in Ions
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Learning Check

• Naturally occurring carbon consists of three
  isotopes, 12C, 13C, and 14C-4. State the number
  of protons, neutrons, and electrons in each of
  these carbon atoms or ions.

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Identification of Elements
When heated elements produce specific colors of
light
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Electromagnetic Radiation
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Electromagnetic Radiation

• Light is emitted from atoms as EM radiation.
• EM radiation is a moving energy wave with
  electrical and magnetic components at right
  angles to each other.
• An EM wave travels at 3x108 m/s and has a
  discrete energy (E), frequency (n) and wavelength
  (?) .
• E hn or E hc/ ? so as E increases n increases
  and lambda decreases.
• h 6.63x10-34 Js and c n x ?

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Emission Spectra
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Emission Spectra

• When a high voltage is applied to a gaseous
  element or compound a specific color of light is
  observed.
• When the light is passed through a prism to
  separate the colors a series of colored lines is
  observed representing energy changes of electrons
  in the atoms.
• The fact that only specific colored lines
  different for each element are observed that this
  stronglt supports the quantitization of electron
  energy.

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Electron Levels (Shells)

• The electrons in an atom are organized into
  shells like layers of an onion
• The shells closest to the nucleus are at the
  lowest potential energy.
• Identified by numbers 1, 2, 3, .. the first
  shell (1) is lowest in energy and so on 1lt2lt3

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Emission Spectrum
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Quantum Theory

• Energy changes in atoms occur in discrete steps
  or jumps
• When energy is absorbed by an atom it goes from
  the ground state to an excited state.
• When the atom returns to the ground state the
  energy is emitted as a photon.
• The difference in energy between the ground and
  excited state determines the color or energy of
  light absorbed or emitted.

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Quantum Theory
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Quantum Theory
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Electron Orbitals

• Orbitals are the specific regions around the
  nucleus were the electrons are found.
• Only two electrons can fit into every orbital.
  They do this by having their magnetic fields
  aligned in opposite directions.
• Orbitals are organized into shells and subshells.

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Electron Shells, Subshells and Orbitals

• Shell numbers (n) indicate the overall size and
  energy of all orbitals in a subshell.
• Shells are identified by the principle quantum
  number (n) 1, 2, 3, 4, etc.
• Subshells are groups of orbitals with the same
  shape in each shell.
• An s subshell has one orbital, a p has three, d
  has five and f has seven orbitals.
• So s subshells hold 2 e-, p holds 6 e-, d holds
  10 e- and f holds 14 e-.

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Relative Sizes of s orbitals

2s
3s
1s
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Other Types of Orbitals
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Relative Energy of Electron Subshells

• Energy
• Levels Subshells
• n 5, 6, 7 7s (2 e-) lt 5f (14 e-) lt 6d (10e-) lt
  7p (6e-)
• n 4, 5, 6 6s (2 e-) lt 4f (14 e-) lt 5d (10e-) lt
  6p (6e-)
• n 4 5 5s (2 e-) lt 4d (10e-) lt 5p (6e-)
• n 3 4 4s (2e-) lt 3d (10e-) lt 4p (6e-)
• n3 3s (2e-) lt 3p (6e-)
• n2 2s (2e-) lt 2p (6e-)
• n1 1s (2e-)

Increasing Energy
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Electron Configurations

• List of orbitals containing electrons written in
  order of increasing energy with superscripts to
  indicate the number of electrons
• Rules for creating electron configurations
• Electrons fill the lowest energy levels first
• Orbitals can hold no more than 2 electrons each
• Fill each orbital in a subshell with one electron
  before pairing
• The order of filling for subshells of atoms is
  1s22s22p63s23p64s23d104p65s24d105p66s24f145d10,
  etc.

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Electron Configuration of Be
Be atoms have 4 electrons which gives the
following electron configuration
This can also be written as He2s2
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Electron Configurations
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Electron Configurations
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Valence Electrons

• Elements in a group are isoelectronic
• N He2s22p3
• P Ne3s23p3
• As Ar4s23d104p3
• Electrons outside the noble gas inner core are
  valence electrons (excludes d orbitals)
• The number of valence electrons can be obtained
  from the second or only digit of the group number