Transcript 3-3 Modern Atomic Theory

3-3 Modern Atomic Theory
By Ms. Pacheco
Parts of the Atom
NAME
Proton
Neutron
Electron
CHARGE
MASS
LOCATION
Parts of the Atom
NAME
Proton
Neutron
Electron
CHARGE
+1
MASS
LOCATION
Parts of the Atom
NAME
CHARGE
Proton
+1
Neutron
0
Electron
MASS
LOCATION
Parts of the Atom
NAME
CHARGE
Proton
+1
Neutron
0
Electron
-1
MASS
LOCATION
Parts of the Atom
NAME
CHARGE
Proton
+1
Neutron
0
Electron
-1
MASS
1 amu
LOCATION
Parts of the Atom
NAME
CHARGE
MASS
Proton
+1
1 amu
Neutron
0
1 amu*
Electron
-1
LOCATION
Parts of the Atom
NAME
CHARGE
MASS
Proton
+1
1 amu
Neutron
0
1 amu*
Electron
-1
0
LOCATION
Parts of the Atom
NAME
CHARGE
MASS
Proton
+1
1 amu
Neutron
0
1 amu*
Electron
-1
0
LOCATION
Nucleus
Parts of the Atom
NAME
CHARGE
MASS
LOCATION
Proton
+1
1 amu
Nucleus
Neutron
0
1 amu*
Nucleus
Electron
-1
0
Parts of the Atom
NAME
CHARGE
MASS
LOCATION
Proton
+1
1 amu
Nucleus
Neutron
0
1 amu*
Nucleus
Electron
-1
0
Electron
cloud
Neutrons are slightly larger
than protons
** Electrons are so small that
their mass is said to be
negligible
*
Henry Moseley
• A British scientist , he is a student of
Rutherford
• In 1913, he makes one of the most
important discoveries in chemistry. He
found out that an atom’s identity comes
from its # of protons (atomic number).
• Moseley was 26 at the time!
• 1915: Sadly, Moseley is killed in battle
in Turkey during WWI.
Said Millikan of Moseley…
• “…Had the European
War had no other
result than the
snuffing out of this
young life, that alone
would make it one of
the most hideous
and most irreparable
crimes in history."
Henry Moseley in his lab…
From Moseley’s ideas, we now
know…
• That since an atom has a neutral
charge, then the number of protons
must equal the number of electrons.
• That an atom that loses or gains
electrons has a charge and is known as
an ion.
How to find the charge of an
ion…
Charge = # P - #E
A magnesium ion has 12 protons
and 10 electrons. What is its
charge?
Charge = # P - #E
= 12-10
= +2
Mg+2
Isotopes…
Are atoms that
have the same
number of
protons, but a
different
number of
neutrons.
Mass number…
• Is the sum of an isotopes
protons plus neutrons.
• Is sometimes written at the end
of the atom’s name. Ex:
carbon-14
carbon-12 v’s carbon-14
• Both are carbon, so both have
6 protons
• Their mass numbers are 12 and
14.
• Due to subtraction, carbon-12
has 6 neutrons and carbon-14
has 8.
Atomic Mass…
• Is the average mass of
an element’s atoms as
they appear in nature.
• The atomic masses of
all elements are based
on the atomic mass of
the carbon-12 atom.
Chlorine’s Isotopes
Chlorine-35
Chlorine-37
75.53%
24.47%
Therefore, the average
mass (atomic mass) of
chlorine is 35.45.