Chemical Interactions

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Chemical Interactions

• Crime Lab Chemistry Chapter 1 Chemical
  Reactions

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Warm Up

• 1. Which ink traveled farthest up your test
  strip?
• 2. Which contained the greatest of different
  colors / pigments?
• 3. Were there any colors that didnt travel up
  paper or separate?
• 4. What ideas do you have as to why some
  traveled higher than others?

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What is Chromatography?

• Chromatography
• Greek word chromos color
• Physical separation of a mixture into its
  individual parts
• Can be used to
• Separate inks dyes, plant pigments
• Determine the chemical composition of substances

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Types of Chromatography

• Liquid Chromatography
• Used to identify unknown plant pigments other
  compounds.
• Thin-Layer Chromatography
• Uses thin plastic or glass trays to identify the
  composition of pigments, chemicals, and other
  unknown substances.

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Types of Chromatography

• Paper Chromatography
• Used to separate the components of inks, dyes,
  plant compounds (chlorophyll), make-up, and many
  other substances
• Gas Chromatography
• Used to determine the chemical composition of
  unknown substances, such as the
  different compounds in gasoline show by
  separate peaks on a graph

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Parts of a Chromatography System

• Test substance
• What youre testing
• Medium
• What test substance moves through
• Solvent
• What helps move the substance

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2-1 Combinations of Elements

• Mixture
• 2 or more substances mixed together but NOT
  chemically combined
• Compounds
• Pure substance made of 2 or more elements that
  are chemically combined (ratio)

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2-1 Combinations of Elements

• Solution
• Mixtures in which one substance is dissolved in
  another
• Have two parts solute and solvent
• The solute is the substance that is dissolved
  (too small to see)
• The solvent is the substance that does the
  dissolving

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Is it made of Molecules?

• Look at the list on your handout which ones do
  you think are made up of molecules?
• Be prepared to explain the
  reasoning you used to make your
  decision

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1-1 Building Blocks of Matter

• All forms of matter are made up of molecules
• Molecules are formed when two or more atoms
  chemically combine to form a larger particle

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1-1 Elements Atoms

• Elements
• Simplest pure substances
• Building blocks of matter
• 90 naturally occurring
• Ex Hydrogen, Gold, Copper, Oxygen

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1-1 Compounds vs. Molecules Whats the
difference??

• Molecules
• 2 or more atoms (can be of the SAME type of
  element OR DIFFERENT types)
• Made up of atoms

• Compounds
• 2 or more DIFFERENT types of atoms (elements)
  that are chemically combined
• Made up of atoms

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1-1 Elements Atoms

• Atoms
• From Greek word atomos meaning uncuttable
• Smallest particle element can be divided into
  still be the same element
• Made of 3 basic
  particles
• Protons ()
• Neutrons (0)
• Electrons (-)

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2-1 Inside the Atom

• Nucleus
• Center of an atom
• Contains protons neutrons
• Same mass (protons/neutrons)
• 2000x larger than electrons

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2-1 Inside the Atom

• Outside Nucleus
• Electrons circle around
• Very large cloud
• protons electrons
• Same - so its neutral
• Valence electrons
• Furthest away from nucleus
• Involved in bonding

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2-1 Inside the Atom
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2-1 Inside the Atom

• of electrons
• Determined from atomic
• Where are the electrons?
• Travel in area outside nucleus
• Energy Levels
• Electron Clouds

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2-1 Inside the Atom
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2-2 Diagrams for electrons

• Bohr diagram

• Lewis / electron dot diagrams
• Outermost energy level w/ dots

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2-2 Atoms in the Periodic Table

• Organization of the Periodic Table
• Categories based on how elements react
• Atomic
• Order
• Also of protons / electrons

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2-2 Atoms in the Periodic Table

• Group / Family
• Same column (up / down)
• 1 18 across top of columns
• Characteristic set of properties based on of
  valence electrons
• Period
• Row (across)
• 1 7 along left side

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2-2 Periodic Table

• Noble Gases (group 18)
• 8 valence electrons
• Except Helium
• Inert (inactive)
• Reactive non-metals (group 17)
• A.K.A - Halogens
• 7 valence electrons
• Looking for 1 electron to react w/

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2-2 Periodic Table

• Reactive Metals (group 1)
• A.K.A. Alkali metals
• Very reactive
• If loose 1 electron ? will have Zero valence
  electron
• Then will become very stable

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2-3 Chemical Bonding

• Chemical Bonding
• Joining of atoms to form new substances
• Not all atoms bond in the same way
• Depends on of valence electrons
• Atoms want a full set of electrons in the outer
  shell

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2-3 Chemical Bonding

• What is a Full Set?
• If only 1 shell 2
• 2 or more shells 8
• Atoms bond by
• Gaining electrons
• Losing electrons

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2-3 Ionic Bonds

• Ionic Bond
• Electron is transferred
• Attraction between oppositely charged ions (like
  magnet)
• Between Metals Non-metals

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2-3 Chemical Bonding

• Ion
• Atom w/ electrical charge
• Lose electron ? positively charged
• Gain electron ? negatively charged

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2-3 Ionic Bonds

• Properties of Ionic Compounds
• Crystal shape
• Solids at room temp.
• High melting points
• Electrical conductivity

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2-4 Covalent Bonds

• Covalent Bond
• Electron Sharing
• Btwn non-metals
• Multiple bonds
• Double bonds
• 2 pairs of electrons are shared (4 electrons)
• Triple Bonds
• 3 pr. electrons shared

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2-4 Covalent Bonds

• Molecular Compounds
• Molecules w/ covalently bonded atoms
• Low melting boiling points
• Poor conductors of electricity