How to use the Periodic Table
When you open any file of an
element in the periodic table, you will find a small table with some basic
information about that element. Here's how you use that table:
5
B
10.81 |
Atomic Number Atomic Symbol
Atomic Mass |
- Atomic Number
The number of protons in an
atom defines what element it is. For example carbon atoms have six
protons, hydrogen atoms have one, and oxygen atoms have eight. The
number of protons in an atom is referred to as the atomic number of that
element. The number of protons in an atom also determines the chemical
behavior of the element.
- Atomic Symbol:
The atomic symbol is one or two
letters chosen to represent an element ("H" for
"hydrogen," etc.). These symbols are used internationally. Typically,
a symbol is the truncated name of the element or the truncated Latin name of
the element. Click here for a list of the elements and their symbols.
- Atomic Mass:
The atomic mass is the average
mass of an element in atomic mass units ("amu"). Though
individual atoms always have an integer number of atomic mass units, the atomic mass on
the periodic table is stated as a decimal number because it is an average of
the various isotopes of an
element. Isotopes can have a weight either more or less than the average.
The average number of neutrons for an element can be found by subtracting
the number of protons (atomic number) from the atomic mass.
- Electron Configuration:
The electron configuration is
the orbital description of the locations of the electrons in an unexcited
atom. Using principles of physics, chemists can predict how atoms will
react based upon the electron configuration. They can predict properties
such as stability, boiling point, and conductivity. Typically, only
the outermost electron shells matter in chemistry, so we truncate the inner
electron shell notation by replacing the long-hand orbital description with
the symbol for a noble gas in brackets. This method of notation vastly
simplifies the description for large molecules.
Example: The electron configuration for Be is 1s22s,2
but we write [He]2s2 where [He] is equivalent to all the electron
orbitals in the helium atom. The Letters, s, p, d, and f designate the
shape of the orbitals and the superscript gives the number of electrons in
that orbital.
Further explanation of the atom may be found Here.
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