BOHR RUTHERFORD
DIAGRAMS
Atoms, Isotopes and Ions
RECALL THE ATOM
• ATOMIC NUMBER:
denotes the number of
protons and electrons in
an atom
• ATOMIC MASS:
denotes the number of
protons plus neutrons in
the nucleus of an atom
HOW DO YOU FIND NUMBER OF
NEUTRONS
• # of Neutrons = ATOMIC MASS – ATOMIC NUMBER
• EXAMPLE: How many neutrons are there in a
Silicon atom?
• SOLUTION:
28
Atomic Mass
--
14
=
14
--
Atomic
Number
=
Number of
Neutrons
ISOTOPES
• Two or more forms of the same element that
contain equal numbers of protons but different
numbers of neutrons
• Differ in relative atomic mass but not in chemical
properties
ISOTOPES OF CARBON
IONS
• An atom with a net
electric charge due to
the loss or gain of one
or more electrons
• There are two types of
ions CATIONS and
ANIONS
CATIONS
• Ions that have a POSTIVE charge
• Created when a neutral atom LOSES an
electron
ANIONS
• Ions that have a NEGATIVE charge
• Created when a neutral atom GAINS an electron
BOHR RUTHERFORD DIAGRAMS
• Used to show the atomic structure of an atom,
isotope or ion.
BOHR RUTHERFORD DIAGRAMS
• RULES for drawing Bohr Rutherford diagrams:
1. Place the number of protons and neutrons in the nucleus
of the atom
2. Place TWO electrons in the first shell. This shell takes a
MAX of two electrons.
3. Place a MAX of eight electrons in all other shells.
4. OCTET RULE: No shell can have more that EIGHT
electrons. If you have extra electrons, add another shell.
PRACTICE
• Draw a Bohr Rutherford diagram
for:
a. Boron
b. Fluorine
c. Argon