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Chemistry Review
Review Video... It’s a long one
Atomic Models
1. Democritus: Indivisible piece of matter called the
atom
2. Dalton: Elements made of atoms all alike &
compounds made of 2+ elements
3. Thomson: Discovered electrons, atoms divisible,
pudding model
4. Rutherford: Protons in nucleus, electrons
scattered around outside
5. Bohr: electrons move in orbits around nucleus,
strongest ones far away from nucleus
6. Wave: small positive nucleus surrounded by
electrons (same # as protons)
Structure of the atom
• Nucleus: (core) contains 99.9% of the mass of the
atom, Contains protons and neutrons
• Protons: Positively charged particle. They are
identical in every element
• Neutrons: Have no charge, identical in every
element, differing numbers in the same element
are called isotopes
• Protons and neutrons are made of smaller
particles called quarks
Electrons
• Electrons whirl around the nucleus in the
electron cloud
• Their mass is smaller than a proton or
neutron
• They have a negative charge
• The number of electrons an atom has
determines its chemical properties
• Electron in outer level are called valence
electrons
Energy Levels
• 1st 2 electrons
2nd 8 electrons
3rd 18 electrons
4th 32 electrons
• The further away from the nucleus, the more
energy it has
Be happy its not you!
Atomic Number and Mass
• The number of protons in the nucleus determines
the atomic number of the element
• The mass number is the sum of the protons and
neutrons and is used to distinguish one isotope
from another
• Atomic mass is the average mass of all the
isotopes of an element
Forces in the atom
1. Electromagnetic force: Keeps the electrons
spinning around the nucleus due to the
repulsion/attraction
2. Strong Force: The greatest of the four forces
3. Weak Force: Responsible for radioactive decay
through fusion
4. Gravity: Force of attraction between objects,
weakest force
Nuclear Stability
Characteristics of Chemical
Reactions
• Formation of a NEW substance, not the original
substance
• Reactant: substance that enters into the reaction
(original substance)
• Product: substance that is produced by a chemical
reaction (new substance)
• The Law of Conservation of Mass states that mass
remains constant in a chemical reaction
Bonding
• If an atom has 8 valence electrons it is stable and
will not bond
• An atom with less than 8 valence electrons is
unstable and will bond readily (easily)
• The ability to bond determines its ability to
undergo chemical reactions
Reaction video
Balancing Equations
• Subscripts, symbols, and formulas cannot be
changed because you would be changing the
substance altogether.
• Coefficients can be added.
• Balance the number of atoms of each element on
both sides to show that no mass has been lost or
gained
Vocabulary
1. Exothermic: Heat, or energy, comes out of, or is
released (gets hot), combustion
2. Endothermic: Heat, or energy, goes into (gets
cold), reaction is the form of heat or light
3. Kinetics: the study of reaction rates
4. Collision Theory: The rate of a reaction is
affected by concentration, surface area,
temperature and catalysts
Periodic Table
Periodic Table
• Dmitri Mendeleev Organized by atomic mass
(weight)
• Henry Moseley, arranged the elements according
to their atomic number
Groups / Families
•
•
•
•
•
•
Groups or families
They have similar properties
Vertical
They have the same number of valence electrons
There are 18 families… be able to name them!!
A,AE,T,B,C,N,O,H,NG
Families
1. Alkali Metal Family: most reactive metals,
violent reaction in water
2. Halogen Family: most reactive nonmetals
3. Noble Gas Family: normally unreactive
Periods/ Rows
• Elements are not alike in the rows
• First element in a row is an extremely active solid,
last is always an inactive gas
• There are 7 periods
• The number of the row they are in tells you the
number of energy levels
• Horizontal
Element stuff you need to
know 
1. Hydrogen is a non-metal
2. Mercury is the only metal in liquid form at room
temperature
3. Most of the elements are metals in solid form
4. The non-metals are in gas form
5. There are only a few metalloids along the zig-zag
line
6. Radioactive elements are mostly man-made
Position on the table
Bonding
1, 2, 3 = lose electrons
5,6,7 = gain electrons
4 = gain or lose
8 = unresponsive
1. Ionic bonding – involves a transfer of electrons.
One atom gains and the other one loses (metal
and non-metal)
2. Covalent bonding –They share electrons, rather
than transfer. (Non-metal and non-metal), from
molecules
3. Metallic bonding: metal and metal, electrons are
able to fly off the energy levels
Dumb Criminals
Vocabulary
• Chemical bonding – the combining of atoms of elements to
form new substances
• Ion – a charged atom (positive or negative).
• Ionization – the process of removing electrons to form ions.
• The energy needed is called ionization energy.
• Electron affinity – the tendency of an atom to attract
electrons.
• Polyatomic ion – when two elements bond first covalently
then through ionic bonding
• Oxidation number – the number of electrons an atom gains
or loses, or shares in a chemical bond.
• Diatomic elements – form bonds with atoms of the same
element.
Radioactivity
1. Becquerel: Provided evidence of x-rays and
Uranium
2. Curie: discovered Radioactive Elements,
Polonium and Radium
3. Rutherford: Produced the first artificial
transmutation
Particles
1. Alpha: Nucleus of He atom, Weakest, Positive
charge, stopped by paper
2. Beta: Electron formed in the nucleus when a
neutron breaks apart, pass through 3 mm of
aluminum
3. Gamma: Electromagnetic wave of high frequency
and short wave length, Strongest, Can pass
through lead
Mutation??
Fission and Fusion
Vocabulary
1. Binding energy: needed for the stability of a
nucleus
2. Radioactive decay: The spontaneous breakdown
of an unstable atomic nucleus
3. Decay Series: The series of steps by which a
radioactive nucleus decays into a non-radioactive
nucleus.
4. Alpha Decay: Occurs when a nucleus releases
an alpha particle
5. Beta Decay: Loses a beta particle causing the #
of protons to go up by 1.
6. Gamma Decay: Release of gamma ray, Nucleus
is not changed only lowered to a different energy
level
7. Transmutation: Where one element changes
into another as a result of changes in the
nucleus (beta decay)
8. Radioactive Half-Life: The amount of time it
takes the atoms in a given sample of an
element to decay
9. Particle accelerator uses magnets and electric
fields to speed up particles
10. Fission: Splitting of an atomic nucleus into 2
smaller nuclei of approximately equal mass, I
Break, power plants
11. Fusion: Joining of 2 atomic nuclei of smaller
mass to form a single nucleus of a larger mass,
U Make, sun and atomic bombs