Mass Number Atomic Number equals the # of... NUCLEUS ELECTRONS PROTONS NEUTRONS NEGATIVE CHARGE...
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Transcript of Mass Number Atomic Number equals the # of... NUCLEUS ELECTRONS PROTONS NEUTRONS NEGATIVE CHARGE...
The ATOMBy convention there is color,
By convention sweetness,By convention bitterness,
But in reality there are atoms and space.
-Democritus (c. 400 BCE)
POSIT IVECHARG E
PROT ONS
NEUT RALCHARG E
NEUT RONS
NUCLEUS
NEG AT IVE CHARG E
ELECT RONS
AT OM
Mass Number Atomic Numberequals the # of...
NUCLEUS ELECTRONS
PROTONS NEUTRONS NEGATIVE CHARGE
POSITIVE CHARGE
NEUTRAL CHARGE
ATOM
Atomic Structure
Scale of the atom
Atomic Mass Units
atomic mass unit (amu) =
the mass of one proton
1.66 10-27 g
Mass Number
Atomic Number
Sum of the protons and neutrons in the nucleus of an atom
Always a whole number
# of neutrons = mass # - atomic #
The number of protons within the nucleus
Atoms of the same element with different numbers of neutrons
Mass #Atomic#
Isotope symbol:
“Carbon-12”
Isotopes
6 C
How to calculate the average atomic mass of an element:
List all isotopes, mass numbers, and percent relative abundance of an element
Multiply the mass number of each isotope by its relative abundance
Add all the products together = atomic mass
Atomic mass is an average
An example:
Chlorine-35 (35Cl) has 17 protons and 18 neutrons and has a relative abundance of
75.8%
Chlorine-37 (37Cl) has 17 protons and 20 neutrons and appears 24.2% of the time.
Multiply the mass number of each isotope by its relative abundance
(Chlorine-35) 35 amu × 0.758 = 26.53 amu(Chlorine-37) 37 amu × 0.242 = 8.95 amu
Add all the products together = atomic mass
26.53 amu + 8.95 amu = 35.48 amu