Chemistry

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Chemistry

• A walk down memory lane
• Or at least it should be

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If you can cook, you can do chemistry!

• The ingredients reactants
• The cake/ cookies product
• You only get out what you put in (Conservation
  of mass)
• Your products do not have the same properties as
  the reactants
• Does a cake taste the same as raw eggs, flour,
  etc?

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Atoms The smallest unit of matter that cannot
be broken down by chemical means
All matter consists of atoms

• Nucleus
• Protons ()
• Neutrons (0)

• Electron Cloud
• Electrons (-)

Nuclei can only be changed by fission or
fusion!
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Electron Clouds
S orbital

• Areas of probability
• Electrons do not really travel in orbits like
  planets
• Bohr Model
• Electrons are in clouds
• The farther from the nucleus, the easier an e- is
  lost

p orbitals
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Elements a pure substance made of only one kind
of atom
Atomic Number

• Each element
• Has a different number of protons
• Has a symbol (one or two letters)
• Organized on the periodic table

36 Kr Krypton 83.80
Symbol
Atomic Weight
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How do we figure out the number of protons,
neutrons, and electrons?

• Atomic Number the number of protons which the
  number of electrons
• Atomic Weight the total mass of the atom.
  Comes from the combination of protons and neutrons

36 Kr Krypton 83.80
Protons atomic number 36 Electrons atomic
number 36 Neutrons atomic weight atomic
number 84-36 48
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Isotopes atoms of the same element that have the
same number of protons, but a different number of
neutrons

• Some isotopes are stable
• Some break apart and release energy (fission)

This is the reason why atomic weights are NOT
whole numbers!
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• Organized by properties Periodicity
• Period horizontal rows
• Group Vertical column
• Valence electrons outermost e-, involved in
  bonding, same as the group number for the main
  block elements

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Patterns in the Periodic Table

• Diameter decreases as you move along the row from
  left to right
• Diameter increases as you move down the column
• Each column reacts similarly, because they have
  the same number of valence electrons
• Metals are on the left and nonmetals on the right

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Lets put some atoms together!

• Compound two or more atoms joined together
• Molecule two or more atoms share electrons

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Types of Chemical Bonds

• Ionic
• Electrons are transferred
• Makes ions when dissolved
• Forms between a metal and a nonmetal
• Covalent
• Electrons are shared
• Forms between 2 nonmetals
• Polar e- are NOT equally shared
• Non-polar e- ARE equally shared
• Dont forget Like dissolves like

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Metallic Bonds

• Electrons move from one atom to the next
• Forms between 2 metals

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Hydrogen Bond

• Between 2 polar MOLECULES
• Weak bond
• Positive and negative charges attract much like
  opposite poles of a magnet

Partially Negative
Partially Positive
This allows for adhesion, cohesion, and
capillary action in water
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Balancing Chemical Formulas

• Step 1 determine the charge of the ion each
  element will form
• Step 2 Write the metal first, the nonmetal
  second
• Step 3 the charge of one atom is the subscript
  of the other

Mg2 Cl-
MgCl2
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Polyatomic Ions

• ion with many atoms
• The atoms in the polyatomic react as if they are
  one atom they do not rearrange
• Written with parentheses around them if more than
  one polyatomic is in the compound
• Mg(OH)2