Download Atomic Structure Notes

Name: _____________________________________________ Date: ______________________________
E.Q. “ What is the structure of an atom?”
An atom is the _smallest______________ unit of ___matter__________.
Atoms are made up of three main sub-atomic particles:
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Proton
Has a positive (+)
electrical charge.
Found in the nucleus
of an atom.
Number of protons =
atomic number.
Number of protons
identifies the
element (atom).
More massive than
electrons.
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Neutron
Has no electrical
charge (neutral).
Found in the nucleus
of an atom.
More massive than
electrons.
Protons + Neutrons =
Atomic Mass
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 Isotopes form when
an element (atom)
has gained or lost
neutron(s).
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Electron
Has a negative (-)
electrical charge.
Have very little
mass.
Move around outside
the nucleus in
orbitals (shells,
energy levels).
Electrons with the
lowest energy are
found in orbitals
closest to the
nucleus.
Higher energy
farther from
nucleus.
 Electrons determine
reactivity (how likely
an atom is to form
bonds).
 Electrons in the
outermost orbital
are called valence
electrons.
 Ions form when an
atom gains or loses
electron(s) through
bonding.