A.
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:
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 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 amus, 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.
