The Why and How of Ions
Featuring the Return of Bohr-Rutherford
Diagrams and the Periodic Table
Bohr-Rutherford Diagrams
Bohr-Rutherford diagrams (or simply Bohr
diagrams) are used to show the
arrangement of electrons in the atom, e.g.:
How To Draw Bohr Diagrams
1) Find your element on the periodic table.
2) Determine the number of electrons, which
for a neutral atom is equal to the number
of ?
How To Draw Bohr Diagrams
1) Find your element on the periodic table.
2) Determine the number of electrons, which
for a neutral atom is equal to the number
of protons, which is equal to the ?
How To Draw Bohr Diagrams
1) Find your element on the periodic table.
2) Determine the number of electrons, which
for a neutral atom is equal to the number
of protons, which is equal to the atomic
number.
How To Draw Bohr Diagrams
3)Determine which
period (row) your
element is in.
Elements in the 1st
period have one
energy level or shell.
Elements in the 2nd
period have two, and
so on.
How To Draw Bohr Diagrams
C
4) Draw a nucleus with
the element symbol
(and optionally, the
#s of protons and
neutrons) inside.
5) Draw the shells
around the nucleus.
Carbon is in the 2nd
period, so it has two
energy levels or
shells.
How To Draw Bohr Diagrams
6) Add the electrons.
C
Carbon has 6 electrons.
The first shell can only
hold ?
How To Draw Bohr Diagrams
6) Add the electrons.
C
Carbon has 6 electrons.
The first shell can only
hold 2 electrons.
How To Draw Bohr Diagrams
You need to add 4 more
so these go in the
2nd shell.
C
The 2nd shell can hold up
to ?
How To Draw Bohr Diagrams
You need to add 4 more
so these go in the
2nd shell.
C
The 2nd shell can hold up
to 8 electrons; the 3rd
shell can hold 18, but
the elements in the
first few periods only
use 8 electrons.
How To Draw Bohr Diagrams
7) Check your work:
Count your electrons
per shell and your
total electrons!
C
Bohr Diagrams: Practice
C
Try drawing Bohr
diagram for each of the
following elements on
your own:
a)
b)
c)
d)
e)
f)
H
He
O
Al
Ne
K
Bohr Diagrams: Practice
H
Try drawing Bohr
diagram for each of the
following elements on
your own:
a)
b)
c)
d)
e)
f)
H – 1 electron
He
O
Al
Ne
K
Bohr Diagrams: Practice
H
e
Try drawing Bohr
diagram for each of the
following elements on
your own:
a)
b)
c)
d)
e)
f)
H
He - 2 electrons
O
Al
Ne
K
Bohr Diagrams: Practice
Try drawing Bohr
diagram for each of the
following elements on
your own:
O
a)
b)
c)
d)
e)
f)
H
He
O - 8 electrons
Al
Ne
K
Bohr Diagrams: Practice
Try drawing Bohr
diagram for each of the
following elements on
your own:
Al
a)
b)
c)
d)
e)
f)
H
He
O
Al - 13 electrons
Ne
K
Bohr Diagrams: Practice
N
e
Try drawing Bohr
diagram for each of the
following elements on
your own:
a)
b)
c)
d)
e)
f)
H
He
O
Al
Ne - 10 electrons
K
Bohr Diagrams: Practice
K
Try drawing Bohr
diagram for each of
the following
elements on your
own:
a)
b)
c)
d)
e)
f)
H
He
O
Al
Ne
K - 19 electrons
Lewis Dot Diagrams
The electrons in the outermost shell
are called ?
Lewis Dot Diagrams
The electrons in the outermost shell
are called valence electrons.
Lewis Dot Diagrams
The electrons in the outermost shell
are called valence electrons.
Lewis Dot Diagrams are abbreviated
Bohr Diagrams that show just these
outermost electrons, e.g.:
Valence Electrons and Families
Note that both hydrogen (H) and
potassium (K) have just ? electron
in their outermost shell.
Note also that these elements are
both found in the ? column of the
periodic table.
This is not a coincidence!
Valence Electrons and Families
Note that both hydrogen (H) and
potassium (K) have just 1 electron
in their outermost shell.
Note also that these elements are
both found in the ? column of the
periodic table.
This is not a coincidence!
Valence Electrons and Groups
Note that both hydrogen (H) and
potassium (K) have just 1 electron
in their outermost shell.
Note also that these elements are
both found in the 1st column of the
periodic table.
This is not a coincidence!
Valence Electrons and Groups
All elements in the same group
(column) have the same number of
electrons in their outermost shell
(ref. p. 150).
It is these electrons that determine
the behavior of the element,
including how it reacts with other
elements – and how it forms ions.
Valence Electrons and Groups
Let’s look at these groups or families
in more detail. . . .
ALKALI METALS
1 valence electron
(Hydrogen is not officially a
member)
• Soft and silvery metals
• Very reactive, esp. with
water
ALKALINE EARTH METALS
2 valence
electrons
• White and
malleable
• Reactive, but
less so
TRANSITION METALS
(the Groups in the
middle)
BORON FAMILY
3 valence
electrons
• Most are metals
• Boron is a
metalloid.
CARBON FAMILY
4 valence
electrons
• Contains metals,
metalloids, and
a non-metal:
carbon (C)
NITROGEN FAMILY
5 valence
electrons
• Contains metals,
metalloids, and
non-metals
OXYGEN FAMILY
6 valence
electrons
• Mostly nonmetals
• Reactive
Halogens
7 valence
electrons
• All are nonmetals
• Very reactive
Noble Gases
Full outer shell
• Exist as gases
• Not reactive with
other elements
• Do not form
ions.
The Why of Ions
The Noble Gases do not react and do not
form ions because they already have what
all atoms want: full outer shells.
The How of Ions
Atoms will either gain electrons to fill their
outer shell (as in the case of the non-metal
chlorine)
The How of Ions
or lose electrons to go down to their last full
shell (as in the case of the metal sodium)
Tune in next time. . . .
More details on the formation of ions will be
revealed tomorrow.
For now, answer the questions:
p. 148 #1-5
p. 150 #1-3
p. 153 #10, 11