1. Atoms and Ions
SNC 2D1

2. Is drinking too much water bad
for you??
 Drinking too much water can
cause hyponatremia
◦ Symptoms: disorientation and
loss of balance
 Excess water can dilute the
concentration of sodium in the
blood to dangerously low
levels (with risk of death if
untreated)

3. What?
Sodium in the blood??

4. No! of course not..
 We are referring to sodium ions
 Many ions are necessary for our
health
Example:
◦ Calcium, phosphorus  components of
bone
◦ Iron  help carry oxygen around body in
blood

5. Atoms vs. Ions
 Atoms are electrically NEUTRAL
particles with equal numbers of e- and
p+
 An ion is an atom that has become
CHARGED by either gaining or
losing electrons in its valence shell

6. Sodium Atom vs. Sodium Ion
 Sodium atoms LOSE one e-
when they react with other
atoms
 Then, each sodium ion
contains 11 p+ and only 10 e-
 Result: sodium ions have an
ionic charge of +1 (a.k.a. Na1+
or Na+)
Na contains
ONE electron in
it’s outer orbit.
Remember…
STABLE orbits
contain 8
electrons!! So
what does this
mean?

7. Fluorine Atom vs. Fluoride Ion
 Fluorine atoms GAIN one
electrons when they react with
other atoms
 Therefore, each fluoride ion
contains 9 p+ and 10 e-
 Result: fluoride ions have an
ionic charge of -1 (a.k.a. F1- or F-)
F-9 contains 7
electrons in its
outer orbit
Remember…
STABLE
orbits contain
8 electrons!! So
what does this
mean?

8. Ions vs. Noble Gases
 Ions are STABLE
 Noble Gases are also
STABLE
 Because they have
filled valence shells…
 Which noble gas has
the same # of e- as
Na+?
 Which noble gas has
the same # of e- as F-
?
 We say Na+ and F- is
isoelectronic to Ne

9. DID YOU KNOW?
 Fluoride ions help make tooth enamel strong
 Fluoride is found in our tap water
 For decades, Canadians have been getting
fewer dental cavities

10. Try This!!
1)Draw the B-R diagram for an
Aluminum atom
2)Draw the B-R diagram for an
Aluminum ion
3)Write the new symbol for the
Aluminum ion
4)What is the Aluminum ion
isoelectronic with? (i.e. what
element has the same # of
electrons as the aluminum ion?

11. Aluminum ion
 Al:
13p+, 13n0, 13e-
 Draw the Bohr-
Rutherford
diagram:
 3 valence e-
 How to reach
stability?
 Gain 5 or lose 3 e-?
What is Al3+ isoelectronic with?
Neon!

12. Try This!!
1)Draw the B-R diagram
for a Sulfur atom
2)Draw the B-R diagram
for a Sulfide ion
3)Write the new symbol
for the Sulfide ion
4)What is the sulfide ion
isoelectronic with?
(i.e. what element has
the same # of
electrons as the

13. Sulfide ion
S: 16p+, 16n0, 16e-
 Draw the Bohr-
Rutherford diagram:
 6 valence e-
 How to reach
stability?
 Gain 2 or lose 6 e-?
What is S2- isoelectronic with?
Argon!

14. Hydrogen
 Unusual element
 Can form +ve and –ve ions
 Achieves stability by gaining one e- to
fill its orbit (H-) or loses its only e- (H+)

15. Naming Ions
 Cations: positive charges
 Same name as the element and add
the word “ion”
 E.g. Sodium  Sodium ion
 Anions: negative charges
 Add “-ide” to the stem of the name
 E.g. Oxygen  oxide ion
 E.g. Phosphorus  phosphide ions