Atoms and the Periodic
table
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v=pO0X6fVre1I&feature=related
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v=1xSQlwWGT8M&feature=relate
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Atoms
• All of the matter around you is
made of atoms.
Atoms are the smallest particle of
matter with constant properties.
All atoms are comprised of three
types of subatomic particles:
• Protons have a positive charge (+).
• Electrons have a negative charge (-).
• Neutrons do not have any charge.
They are electrically neutral.
The nucleus of atom contains
neutrons and protons.
Electrons orbit the nucleus.
http://www.youtube.com/watch?v=ZB7B_796mVs&fe
ature=related
• Nucleus: The core of
the atom that
contains two different
subatomic particles.
• Protons: Have a positive
charge.
• The number of protons
equals the number of
electrons.
• Neutrons Have no
Charge.
• Electrons Negative
charge.
• .
Atomic Number
• The atomic number is the
number of protons in the
nucleus of an atom. It is listed
on the periodic table for each
element.
• No two elements have the
same atomic number (or the
same number of protons), so
the atomic number identifies
the element.
How to calculate # of
neutrons
• Atomic mass - Atomic number = # of
neutrons
Count the
number of
protons. What
element is it?
This element
is Nitrogen. Its
mass is 14. So
atomic # of 7,
minus atomic
mass of 14,
equals 7
neutrons.
Mass Number
• Mass number: is the total number of
protons and neutrons in the nucleus.
• For example:
• 23Na
11
represents a sodium atom which always
has 11 protons and in this case has a
mass number of 23.
(Note: This means that there are 12
neutrons. 23 - 11 = 12)
•
•
•
•
Mass number
- atomic number
________________
= # neutrons
The Periodic Table arranges
atoms according to their
number of protons
The number of protons is also the
atomic number for an atom
Atomic Numbers, Symbols
and Mass
• Atomic
number
is the
smaller
number
and the
number
of
protons
in the
nucleus.
47
Ag
Silver
Element
Symbol
Element
Name
107.868
Atomic mass is all the
protons and neutrons added
together.