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Atoms and Isotopes

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					                         Atoms and Isotopes

Atoms are basic particles from which matter is built. They have a small
nucleus consisting of protons and neutrons (with one exception, which is
hydrogen.) Around the outside they have electrons, which orbit the
nuclei.

The particles that make up atoms have different relative masses.

     PARTICLE               RELATIVE MASS                 CHARGE
Proton                             1                                   1+
Neutron                            1                                    0
Electron                        1/1840                                 1-

All atoms of an element have the same number of protons. This is called
the Atomic Number.

The number of protons combined with the number of neutrons is called
the Mass Number.

An example of a simple atom is Helium:
                                                    Neutron (neutral)
                                                    Neutrons have the
Proton (positive)                                   same mass as protons.
Atoms have the same
number of protons as
electrons. This makes the
atom neutral.                                       Electron (negative)
                                                    Same number as
                                                    protons, they have a
                                                    mass of almost
                                                    nothing.

Atoms in the periodic table are all written in the following way:

Mass Number        4


                       He
(protons + neutrons)
                                                           Symbol
Atomic Number
(protons)          2
Isotopes
The number of protons in an element, defines which element that atom is.
However some atoms of the same element can have different numbers of
neutrons. This is what isotopes are.

They have the same chemical properties as they have the same number of
protons and electrons. They stand out from normal elements as they have
different numbers of atomic numbers to mass numbers:

Chlorine has 2 isotopes:




Isotopes have the same reactions as the usual type of a certain element, as
they have the same electron configuration.

Atoms and isotopes are similar in that they create atoms with the same
reactions and chemical properties, however they are different because
they have for instance different atomic masses.

				
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