Download Atoms and the Periodic Table

Boxes on the
Periodic Table
What do they tell us??
Boxes on the Periodic Table

The boxes on the Periodic Table give the
following information about an element:
symbol
 atomic number
 atomic mass

Symbols

One or two letter abbreviation for an
element’s name
Atomic Number (smaller)
The number of protons or electrons in an
atom of an element
 The periodic table is arranged in order of
increasing atomic number

Atomic Mass (bigger)
The average mass of one atom of an
element
 Measured in atomic mass unit (amu)
 The protons and neutrons add to make
up the atom’s mass – (the electrons are
too small to count)

Calculating Subatomic Particles
3
Atomic Number
Li
Element Symbol
Lithium
Element Name
6.941
Atomic Mass
Atomic Number = __3_
Atomic Mass = _7__
(protons + neutrons)
# Protons = _3__
(the atomic number)
# Electrons = _3__
(the atomic number)
# Neutrons = __4_
(7 – 3)
Calculating Subatomic Particles
Element
Symbol
Atomic
Number
Copper
Ca
Atomic
Mass
# proton
64
29
40
19
(atomic
number)
#
electron
#
neutron
(atomic
number)
(atomic mass –
atomic number)
I have noticed…

Atoms are neutral – same number of
protons (+) and electrons (-)
 Neutrons

are neutral, so they don’t count!
Only 2 of the 3 subatomic particles make
up an atom’s mass; the protons and
neutrons
And lastly…
If you change the number of protons in an
atom you have another element
 If you change the number of neutrons in
an atom you have an isotope
 If you change the number of electrons in
an atom you have an ion that is ready for
bonding
