Chemical Elements
Basic Information
Symbol
Each element is assigned a chemical
symbol. This symbol usually originates
from its name or its Latin name. For
example, silicon has a chemical symbol
"Si". Each element's symbol is composed
of a capital letter followed by one or two
lowercase letters.
Atomic Number
Each atom has an atomic number. This
atomic number is equal to the number of
protons in the nucleus of that particular
atom. For example, the element cobalt
(Co) has an atomic number of 27. This
atomic number is also the number of
protons in the atom. Therefore, Co has 27
protons.
Atomic Mass Unit or Number
The mass of an atom, expressed in atomic
mass units (AMU), is roughly equal to the
number of protons plus the number of
neutrons. This is because both the protons
and the neutrons in an atom have a
relatively equal mass. The mass of an
electron is so insignificant that it is not
represented in the atomic mass.
Melting Point
 The melting point of any element is the
temperature at which the element changes from
a solid to a liquid or from a liquid to a solid. Even
though water is not an element, I will be using it
in this example. Water freezes and ice melts at 0
°C (32 °F). Therefore, the melting point of water
is 0 °C. The melting point is provided in degrees
Celsius, Fahrenheit, and Kelvin. The melting
point of a substance is also the freezing point.
Boiling Point
 The boiling point of any element is the
temperature at which it changes from a liquid to
a gas or from a gas to a liquid. You probably
know that water changes to steam and steam
changes to water at a temperature of 100 °C
(212 °F). The boiling point of water is 100 °C.
Therefore, the boiling point is also the
condensation point. The boiling point is provided
in degrees Celsius, Fahrenheit, and Kelvin.
Number of Protons/Electrons
 The number of protons/electrons in any atom is
always equal to the atomic number of the atom.
Each atom has a neutral charge, and since a
proton has a positive charge and an electron
has a negative charge, in order to achieve a
neutral charge, the number of protons and
electrons must equal. A particle that is not
neutral (has either more or less electrons) is
known as an ion.
Number of Neutrons
The number of neutrons in an atom is
equal to the number of protons in an atom
subtracted from the mass of the atom
rounded to the nearest integer.
Number of Energy Levels: 6
 First Energy Level: 2
Second Energy Level: 8
Third Energy Level: 18
Fourth Energy Level: 32
Fifth Energy Level: 18
Sixth Energy Level: 6
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Classification
The classification of any element relates to its
properties. Each periodic table may use
different group names and classify each
element a little differently. This periodic table
uses 9 families:
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Alkali Metals
Alkaline Earth Metals
Transition Metals
Other Metals
Metalloids
Non-Metals
Halogens
Noble Gases
Rare Earth Elements
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Element Name Polonium
Atomic Number: 84
Atomic Mass: 209
Protons: 84
Neutrons: 125
Electrons: 84
Configuration: 2-8-18-32-18-6
Element Type: Metalloid
Family: Oxygen
Period: 2
Group: 16
Interesting Facts about Element Polonium:
Ex. They use Polonium in nuclear batteries for space
equipment.
Atomic Structure
 Number of Energy Levels- The number of energy levels refers to how
many "electron shells" or places where electrons can be an element has.
An element with 4 shells, such as zinc (Zn), has 4 different areas where an
electron is likely to be found.
 Electron Arrangement- The electron arrangement of an atom refers to the
number of electrons in each energy level. For example, carbon (C) has 6
electrons. Its atom arrangement shows that the six electrons are divided up
into two shells, with 2 and 4 electrons, respectively.
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Electron Configuration- The electron arrangement described above can
be further described to include information about orbitals, shells, and more.
This explanation is beyond the scope of this document, but if you are
already aware of what these numbers mean, they are provided here for
you.
 Bohr Models- On this periodic table, Bohr models are now available for all
112 known elements. These models are designed to give some idea of how
the electrons are spread over the energy levels. However, the Bohr model
is now considered inaccurate among most scientists. This is because Bohr
models show that electrons travel on specific paths or orbitals, a theory
which has now been replaced by one that states that an electron has a
greater probability of being in a certain area (or "energy level") of the atom.