Ionic Bonds and Compounds
Ionic Bonds and Compounds
(in a future unit we'll learn about covalent or molecular bonds and
compounds)
Ionic Bonds and Compounds
Dogs can teach chemistry!
Ionic Bonds and Compounds
So can stick figures ...
Except for the noble gasses, atoms of all elements are unstable!
All chemical reactions occur so atoms can achieve stability.
Atoms achieve stability when they have full electron energy levels. That
is, when they have a "noble gas configuration" of electrons.
Metals
Metals, having 1, 2, or 3 valence electrons, can become stable (full energy
levels) by losing electrons.
When metals lose electrons, they become positive ions, known as cations.
Non-Metals
Non-metals, having 5, 6, or 7 valence electrons, can become stable (full
energy levels) by gaining electrons.
When non-metals gain electrons, they become negative ions, known as
anions.
So...
metals form positive ions
non-metals form negative ions
So...
metals form positive ions
non-metals form negative ions
Mini-Quiz #1
What charge do the following atoms have when they lose or gain electrons to become ions?
Li
Cl
Mg
Na
O
Al
S
N
Se
P
F
Ca
Br
K
Be
Al
Ba
Fr
BUT... atoms can't just gain or lose electrons in isolation. They must have another atom
to give to or take electrons from.
Metals (that want to lose electrons), transfer electrons to nonmetals (that want to gain
electrons).
The metal atoms become positive ions, and the nonmetal atoms become negative ions.
These oppositely charged ions attract each other forming IONIC BONDS.
Using Lewis Dot structure to understand Ionic Compound formation
(remember: Lewis Dot structures consist of an atom's symbol surrounded by dots representing valence electrons)
Na
+
Cl
Mg
+
O
Mg + Cl
Na + O
Al + Cl
Al
+ O
Ions always combine in ratios that neutralize the charges. So the ionic
compound has an overall zero charge.
Ionic compound formulas are always written with the positive ion first!
2+2
4
landscape
Mini Quiz #2 Balance the following formulas
A
Ca Cl
Ca O
Na N
K Cl
KO
Ba N
B
Na F
Na S
Na O
Mg N
Ba O
Na Br
Polyatomic Ions
As the name implies, polyatomic ions are made of several atoms.
These atoms are joined by strong covalent bonds (which we'll study in
another unit).
For now, just think of them as a group of atoms glued together that, as a
group, have a charge.
Polyatomic Ions
Polyatomic ions are everywhere and are important.
The sooner you learn to recognize them, the easier your understanding of
chemistry will be.
You will need to memorize 10 of the most common (there are MANY
more).
The ten you need to know are:
Ammonium
NH4
Sulfate
+1
SO4
Carbonate
Nitrate
-2
CO3
-2
NO3
-1
ClO3
Chlorate
-1
Permanganate
-1
Acetate
-1
Hydroxide
MnO4
Chromate
CrO4
-2
Phosphate
PO4
-3
C2H3O2
OH
-1
C2H3O2
NH4
Acetate
-1
Ammonium
+1
CO3
Carbonate
-2
ClO3
Chlorate
-1
CrO4
Chromate
-2
OH
Hydroxide
-1
NO3
Nitrate
-1
MnO4
PO4
Permanganate
Phosphate
-3
SO4
Sulfate
-2
-1
Acetate
C2H3O2
-1
Ammonium
NH4
+1
Carbonate
CO3
-2
Chlorate
ClO3
-1
Chromate
CrO4
-2
Hydroxide
OH
-1
Nitrate
Permanganate
Phosphate
-3
Sulfate
NO3
-1
MnO4
-1
PO4
SO4
-2
Polyatomic ions act just like single-atom ions.
They bond with ions of the opposite charge in
the same way.
Binary Compound
(made of 2 elements)
Ca+2
Cl-1
with
Ternary Compound
(made of more than 2 elements -- includes a polyatomic ion)
Ca+2
with
NO3-1
Illustration:
NO3-1
Cl-1
Ca+2
Ca+2
Cl-1
NO3-1
Formula:
Ca Cl2
Ca (NO3)2
Instructions for constructing ionic compound activity.
If needed, cut out ions.
Match one type of cation (+ ion) with one type of anion (- ion) in ratios that
result in a rectangle (zero overall charge).
Always list the positive ion first
Fill in the missing information
Name
Formula
Charge
Sulfate
PO4
Ammonium
C2H3O2
MnO4
Nitrate
CO3
Hydroxide
Mini Quiz #4 Balance the following formulas
K SO4
Ba PO4
NH4 OH
NH4 C2H3O2
Ba C2H3O2
K MnO4
NH4 SO4
NH4 Cl
Al NO3
K OH
Mg CO3
K SO4
Attachments
Dogs Teaching Chemistry - Chemical Bonds.mp4