11/20/15
The Periodic Table – organizes elements into Groups and Periods.
1) Periods: (7) a set of elements that runs left to right 
a. They are arranged to increase by atomic number
i. The atomic number is the number of protons and (in a stable atom,) the
number of electrons in an atom.
2) Groups: (8 or 18) groups are arranged according to the number of electrons in the outer shell of
the atom.
Alkali Metals: Group 1
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Lose one electron (one electron in the outer shell)
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Very reactive
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Do not exist freely in nature
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Have the characteristics of all metals:
o
Are malleable – bendable
o
Are ductile – can be strung into wire.
o
Are good conductors of heat and electricity.
Alkaline Earth Metals Group 2
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Two electrons in the outer shell
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Lose two electrons
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Very reactive
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Typical metals
Transition Metals
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38 elements
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Have properties/characteristics of metals
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Iron, cobalt, and nickel produce a magnetic field.
Other Metals
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7 elements in this group
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They are ductile and malleable
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They are solids, have a relatively high density, and opaque (not see-through)
Group – Metalloids
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Possess properties of metals and non-metals.
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Carry an electric charge under special conditions
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Semi-conductors: silicon and germanium
Group – Non-Metals
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Characteristics:
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1) don’t reflect light
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2) not conductors
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3) very brittle
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4) not ductile or malleable.
Group 7 – Halogens
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Salt forming elements
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Compounds from these are called salts
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7 electrons in the outer shell
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They exist as solids, liquids, or gases at room temperature.
Group 8 – Noble gases
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Inert or stable
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8 electrons in the outer shell (valence electrons)
Group – Rare Earth Elements
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30 elements
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Trans-uranium – man-made or synthetic.