Atoms, Molecules and Ions

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Atoms, Molecules and Ions
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Daltons Atomic Theory

• Ea element is composed of small particles called
  atoms.
• All atoms for a given element are identical diff
  elements are diff w/ diff props.
• Atoms are not changed by chem rxns not created
  or destroyed
• Comps form when atoms of more than 1 element
  combine in a fixed ratio

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Chemical Physical Properties

• Physical - a characteristic th can be observed or
  measured w/out changing the sub.
• Chemical - the ability of a sub to undergo chem
  rxns form new subs.

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Law of Constant Composition

• In a given comp, the proportion of elements is a
  fixed quantity.
• H20 H2O2

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Law of Conservation of mass (Matter)

• The total mass of products after a rxn is the
  same as the total mass before the rxn.

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Law of Multiple Proportions

• Diff comps can be made of the same elements
  having diff proportions
• H2O H2O2

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Discovery of Atomic Structure (subatomic
particles)

• J.J. Thomsons study of cathode rays lead to the
  discovery of the electron (e-)
• Plum pudding model

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Radiation

• Energy or particles th are spontaneously emitted
  from a nucleus
• Alpha He nucleus 2He
• 2
• Beta an electron 0e
• -1
• Gamma high- E radiation

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Rutherfords Gold Foil Experiment

• Bombarded gold foil w/ alpha particles
• Most passed through
• A few were strongly repelled
• Indications
• Atom is mostly empty space
• Dense, positive nucleus
• Chadwick discovers neutrons

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Rutherford- Bhor Model

• Planetary model
• Dense, positive nucleus
• E-s surround in fixed orbitals

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Modern Atomic Theory

• E- Cloud
• A dense, positive nucleus surrounded by an e-
  cloud

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Subatomic Particles

• Particle Charge Mass (amu)
• Proton 1.0073
• Neutron 0 (neutral) 1.0073
• Electron - 5.486 x 10 -4

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Atomic Numbers, Mass Numbers, Isotopes

• Atomic number
• of protons
• Identifies an element
• Elements are arranged on P- table by atomic
• Mass the sum of protons neutrons
• Isotope an alternative form of an element th
  has a diff of neutrons so a diff mass
• Nuclide 12C
• 6

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Atomic Weights (masses)

• Relative to C-12
• H, being the lightest is assigned a value 1
• Amu - atomic mass units

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Average Atomic Mass

• Accounts for the mass and relative abundance of
  ea isotope for an element
• For C
• (.9893)(12 amu) (.0107)(13.00335) 12.01 amu

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Periodic Table

• Arranged by atomic
• 7 periods (rows)
• 18 groups or families (columns)
• Have similar props valence structure
• 1A alkali metals
• 2A alkaline earth metals
• 6A chalcogens
• 7A halogens
• 8A noble gases
• Metals left side
• Nonmetals right side
• Metalloids (semiconductors) along stairstep

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Molecules Molecular Comps

• 2 or more nonmetals bound together
• Diatomic molecules
• N2, Cl2, Br2, O2, H2, I2, F2
• Nobody Can Beat Our Highschool In Football

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Molecular Empirical Formulas

• Molecular formula - indicates the actual numbers
  types of atoms
• CO2 CH4
• Empirical formula - simplest whole ratio of
  elements in a comp
• H2O2 -gt HO

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Structural Formulas

• Shows wh atoms are attached to wh w/in a molecule

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Ions Ionic Comps

• Ions - charged particles occurs when a neutral
  atom loses or gains e-s.
• Cation - a ion
• Na -gt Na 1-
• Anion - a - ion
• Cl -gt Cl 1-
• Polyatomic ions - atoms joined as in a molecule,
  but have a net or - charge
• NO3 1-

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Predicting Ionic Charges

• Atoms lose or gain e-s to achieve the nearest
  noble gas valence configuration
• Results in a stable (full) valence level
• Na -1 e- -gt Na as Ne
• Cl 1 e- -gt Cl- as Ar

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Ionic Comps

• Composed of metals (cations) nonmetals (anions)
• Results fr e- transfer
• Na loses 1 e- Na
• Cl gains 1 e- Cl-
• Opposites attract NaCl
• Always neutral BaCl2
• Arranged in a 3-D crystal lattice, so only
  empirical formula are written

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Names Formulas of Ionic Comps

• Binary Comps
• Name the metal ion first
• Change the ending of the nonmetal ending to -ide
• NaCl
• sodium chloride

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Names Formulas of Ionic Comps -cont.

• Polyatomic Ions
• Name the metal () ion first
• Name the PA as is
• Na2SO4
• Sodium sulfate
• NH4Cl
• ammonium chloride

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Naming Molecular Compounds

• Greek Prefixes are used to indicate the number of
  each element
• 1- mono 6- hexa
• 2- di 7- hepta
• 3- tri 8- octa
• 4- tetra 9- nona
• 5- penta 10- deca
• mono may be dropped on the first word only

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Molecular (Greek) Binary

• CO carbon monoxide
• CO2 carbon dioxide
• P4O5 tetraphosphorus pentaoxide

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Roman Numbers

• Used for ions w/ multiple oxidation states
• Esp. common w/ transition metals
• Put Roman number in parentheses following the ion
• ONLY USED IN NAMES!!!
• FeO iron (II) oxide
• Fe2O3 iron(III) oxide

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Names Formulas of Acids

• Acids subs th produce H in water
• Formula always begin w/ H
• Acid Names
• Anion ending Acid name
• -ide hydro ___ ic
• -ate -ic
• -ite -ous

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Writing Formulas

• Sum of the oxidation numbers must always zero
• Subscripts are added to create a neutral formula
• Sodium chloride Na and Cl- NaCl
• Calcium chloride Ca2 and Cl- CaCl2
• Sodium oxide Na and O2- Na2O

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Formulas w/ PA Ions

• When multiple PA ions are needed to make a
  neutral formula
• Put the entire PA ion in ( )
• Add the subscript ouside of the ( )
• Aluminum hydroxide
• Al(OH)3

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Simple Organic Names

• Alkanes - simplest class of hydrocarbons
• Contain C wh makes 4 single bonds (saturated)
• Count of Cs in a chain to determine prefix
• 1 C methane
• 2 C ethane
• 3 C propane
• gt 4 C use previous Greek prefixes

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Derivatives of Alkanes

• Alcohol - occurs when a H is replaced w/ an -OH
  (hydroxyl) functional group in a hydrocarbon
• Change suffix to -ol
• Methane -gt methanol
• Ethane -gt ethanol
• A will indicate on wh C the OH is bonded
• 1- propanol

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Alkenes

• Contain at least 1 CC (unsaturated)
• Prefixes determined by counting Cs
• Suffix is -ene
• Ethene
• Propene
• 2- butene
• denotes the C fr wh the originates

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Other Organics

• Organic Acids
• Contain the func group COOH
• Suffix of -oic acid ethanoic acid
• Ketones
• Contain the func group CO, on in inside C
• Suffix of -one
• Propanone (acetone)