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Basic atomic structure
The atom is composed of a nucleus, at it's centre,
surrounded by electrons.
In an atoms nucleus there are two types of subatomic
particles named protons and neutrons.
. Nucleus
Overall positive
Negative charge
Proton No charge
Positive charge…read more

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Protons have a positive charge,
and are located in the nucleus. The
number of protons determines the
`Atomic number' of an element
Electrons have a negative charge, and are
organized into `shells' or `energy levels' around
the nucleus. They are kept in their energy level
due to the force of opposite attraction between
the negative electron and the positive proton.
The number of electrons in an element equal the
number of protons, as this makes the element
electronically stable.
Neutrons have no charge, and are located in
the nucleus. The number of neutrons in an
element can be established by subtracting
the proton number from the relative atomic
mass number.…read more

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Proton Numbers
The proton number (otherwise known as the atomic number) refers to the
number of protons in an atoms nucleus. In an atom of neutral charge, the
proton number equals the number of electrons.
The number of protons also determines what element the atom is and
where it is located on the periodic table, as it is arranged in ascending
order of atomic numbers (when reading from left to right across the table.
If you are reading down the columns the elements are ordered in the
ascending number of electron energy levels).
For example, an atom with 67 protons will always be holmium whereas
an atom with 1 proton with always be hydrogen.
Proton number
(Or atomic number)…read more

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Atomic Mass and
The atomic mass is the total mass of the protons, neutrons and
electrons in an atom. Electrons have almost no mass so a rough
estimate of how many neutrons in an atom can be calculated by
subtracting the proton number from the total atomic mass.
Isotopes are variants of atoms of a particular element, which
have different numbers of neutrons. Atoms of a particular
element must have the same number of protons, but the
neutron number can differ without changing the element.
For example, Carbon-12 has 6 protons (as every carbon atom
does) and has 6 neutrons, whereas Carbon-14 has 6 protons
and 8 neutrons. They are the same element but are known as
isotopes of the element.
Atomic mass
There are 15 known isotopes of carbon…read more

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Electron Arrangements
Electrons in an atom are arranged into energy levels.
These energy levels each hold a specific number of electrons.
For example the first level holds 2 electrons,
while the second hold 8.
E.g. Calcium with it's arrangement 2-8-8-2
In transition metals the energy levels begin to
overlap and the electron arrangement
becomes slightly more complicated, as they
are able to put more than 8 electrons on the Sc
second to last energy level of their atoms.
E.g. Scandium with it's arrangement 2-8-9-2…read more


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