Below you will find a list of dates and what was known about the elements or the structure of the atom at this time.  When designing your first table you can use only the facts available at the time of discovery of your element.  That means anything that predates your discovery.  When doing your second table you are working in the present so you can use any information available today.

Ancient Civilizations:

• Density

• Melting Point

• Boiling Point

• Appearance

• Phase (solid, liquid, gas at STP)

• Reactivity

• Macroscopic crystal structure

1600's:

• Atomic mass

1800's:

• Composition of compounds formed

1897:

• Discovered electron

1900:

• Discovered Protons

1911:

• Proved the charge on the electron

1912:

• Found isotopes

• Concept of average atomic mass

1914:

• Atomic number

1932:

• Discovered Neutron

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