CHEM 101L Chapter Notes - Chapter 2.3: Alkali Metal, Dmitri Mendeleev, Francium
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9 Oct 2016
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CHEM 101: The Periodic Trend of the Periodic Table
Before getting into the periodic table and the reason behind its organization,
let us understand that the mass behind all atoms is consisted of manly
neutrons and protons and not electrons. Since protons and neutrons reside in
the nucleus, the nucleus is where most of the mass is concentrated, and then
we have a lot of empty space and electrons orbiting around the nucleus
because of the electromagnetic forces between the protons and the electrons.
The combination of these proton and neutron masses is what is known as the
atomic mass of an element.
Next let us understand what electronegativity is. Electronegativity is how well
an element interacts with an element of the opposite charge. This helps us
identify and predict the products of a reaction because of how well an element
will react with other elements and see if they will form a compound or not.
Dimitri Mendeleev organized the known existing elements in such a pattern
based upon their given properties, first he arranged them given on the atomic
mass of the element. Next he found that the atomic radii would increase as
you went to the right of his arranged periodic table and also increase as you
went down the table. Lastly he also found that the electronegativity of these
elements in arranged order went from least to greatest, starting at Francium
leading up to Fluorine diagonally across the periodic table in a north-
northeast direction.
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