IONS UNIT 1B.10
Ionic Bonding
https://www.youtube.com/watch?
v=g_hwgHGeRhA
https://www.youtube.com/watch
?v=WWc3k2723IM
https://www.youtube.com/watch?v
=hiyTfhjeF_U
Bohr’s Model
 Electrons move like planets around the
sun.
 In circular orbits at different levels.
 Amounts of energy separate one level
from another.
III. The Bohr Model of the Atom
A. Electrons of hydrogen circle the
nucleus in orbits
1. orbits have a fixed amount of energy
in the ground state
2. orbits are a fixed distance from the
nucleus
3. orbits furthest from the nucleus have
the greatest energy
Niels Bohr
(1885 – 1962)
Bohr Model of the Atom
Bohr’s Model
Nucleus
Electron
Orbit
Energy Levels
Bohr’s Model
Fifth
Increasing energy
Fourth
Third
Second
}
First
Nucleus
 Further away from
the nucleus
means more
energy.
 There is no “in
between” energy
 Energy Levels
IONS
 An atom usually has a neutral charge. That
means it has the same number of protons
as electrons
 Remember, a proton has a positive charge and an
electron has a negative charge
 ION – an atom that has lost or gained one or
more electrons and has become charged
either positively or negatively
Positive Ions
 When an atom LOSES electrons, it
becomes more POSITIVE
– Why?
 If you are getting rid of negative particles
(electrons) but your number of positive
particles (protons) are staying the same.
– In other words, you are subtracting negative
numbers
Examples
 What would the charge be if:
 The neutral form of Gold (Au) lost 4 of its 79
electrons. It now has 79 protons and 75
electrons
 The neutral form of Mg lost 2 of its 12
electrons. It now has 12 protons and 10
electrons.
Negative Ions
 When an atom GAINS electrons it becomes
more NEGATIVE
– Why?
 Electrons have a negative charge, so the
more you have, the more negative you
become
Representing Ions
 Ions are represented by placing a
“superscript” charge number next to the
atomic symbol.
 Ex.
– O-2 = oxygen with a negative 2 charge
– K+ = potassium with a positive 1 charge
– N-3 = nitrogen with a negative 3 charge
– And so on
A. Chemical Bond and
valence electron
1.The electrons responsible for the chemical
properties of atoms are those in the outer
energy level: VALENCE ELECTRONS.
a.Valence electrons - The electrons in
the outer energy level.
b.Inner electrons -those in the energy
levels below.
Keeping Track of Electrons
2. Atoms in the same column
a. Have the same outer electron configuration.
b. Have the same valence electrons.
c. Easily found by looking up the group number
on the periodic table.
d. Group 2A - Be, Mg, Ca, etc.2 valence electrons
 List the number of valence shell electrons
are in each of the elements in groups
 1-2 13-18
B. Electron Dot Diagrams: Lewis
Structures
1. A way of keeping track of valence
electrons.
2. How to write them
3. Write the symbol.
4. Put one dot for each valence
electron
5. Don’t pair up until they have to
X
The Electron Dot diagram for
Nitrogen
Nitrogen has 5 valence
electrons.
 First we write the symbol.
Then add 1 electron at a
time to each side.
Until they are forced to pair up.

N
Write the electron dot diagram
for
Na
Mg
C
O
F
Ne
He
C. Ion Formation in Representative
Elements
Group
Gain or Lose
Charge of Ion
1 (1A)
lose 1
+1
2 (2A)
lose 2
+2
13 (3A)
lose 3
+3
14 (4A)
lose or gain 4*
+4,-4*
15 (5A)
gain 3
-3
16 (6A)
gain 2
-2
17 (7A)
gain 1
-1
C. Electron Configurations for
Cations
1. Metals lose electrons to attain noble gas
configuration.
2. They make positive ions.
3. If we look at electron configuration it makes
sense.
 Na 1level- 2e

2 level -8e

3 level -1e: 1 valence electron
Electron Dots For Cations
 Metals will have few valence electrons
Ca
Electron Dots For Cations
 Metals will have few valence electrons
 These will come off
Ca
Electron Dots For Cations
 Metals will have few valence electrons
 These will come off
 Forming positive ions
+2
Ca
D. Electron Configurations for
Anions
1. Nonmetals gain electrons to attain noble
gas configuration.
2. They make negative ions.
3. If we look at electron configuration it
makes sense.
 S 1s22s22p63s23p4: 6 valence electrons
 S-2 1s22s22p63s23p6: noble gas
configuration.
Electron Dots For Anions
 Nonmetals will have many valence
.electrons.
 They will gain electrons to fill outer shell.
P
-3
P
E. Stable Electron Configuration
1.All atoms react to achieve noble gas configuration.
2.Noble gases 8 electrons on last energy level.
3. 8 valence electrons .
4. Also called the octet rule.
Ar
Write the electron
configuration diagram label as
anion
or
cation
 Na






Mg
P
O
F
Cl
K
I. Chemical Bonds
 A. The force that holds two atoms together.
1. Why do atoms form bonds?
a. to acquire 8 electrons in the
valence shell (like noble gases
2. How do atoms form bonds?
a. atoms may lose, gain or share
electrons to get 8 in the valence
shell
I. Properties of Ionic Compounds
Ionic_Bonds.asf
View Ionic video
a. Crystalline structure.
b. A regular repeating arrangement of ions in
the solid.
c. Structure is rigid.
II. Ionic Bonding
A. Anions and cations are held together by
opposite charges.
B. Ionic compounds are called salts.
C. Simplest ratio is called the formula unit.
D.The bond is formed through the transfer of
electrons.
E. Electrons are transferred to achieve noble
gas configuration.
II. Formation and Nature of Ionic Bonds
F. 1. atom “M” loses electron(s)  cation
2. atom “N” gains electron(s)  anion
3. cation and anion attract each other
a. electrostatic attraction
4. the electrostatic force that holds the
oppositely charged ions together is
the ionic bond
Sodium loses an electron forming a (+) ion.
Chlorine gains an electron forming a ( - ) ion.
Electrostatic attraction between the (-) and (+) ion forms
the ionic bond between sodium and chlorine
B. Ionic Compounds
1. compounds containing ionic bonds
2. types of ionic compounds
a. oxides – metal + oxygen
Na2O, CaO,
Al2O3, Fe2O3
b. salt – metal + nonmetal
NaCl
CaF
AgCl
KI
c. binary compounds – two elements
1)all of the compounds in a and b
are binary compounds
 D. monoatomic ion - one atom
1) ex. K+ Fe3+ O2- N3E. polyatomic ion – ion with more than
one atom that acts as a single ion
NO3- OHSO42NH4+
III. Names and Formulas
A. Formulas for Ionic Compounds
1. vocabulary
a. formula unit – simplest ratio of
ions in a compound
1) ex. NaCl MgBr2 AlCl3
b. monoatomic ion - one atom
1) ex. K+ Fe3+ O2- N3-
B. Formulas For Ionic Compounds
1. write formula for the cation first, then
the anion
2. use subscripts to indicate number of
ions (criss-cross the charges)
a. sum of charges should equal 0
b. never change subscripts in
polyatomic ions
Sodium Chloride Crystal
Ionic Bonding
Na Cl
Ionic Bonding: Lewis Structure
+
Na
Cl
-
Ionic Bonding
 All the electrons must be accounted for!
Ca
P
Ionic Bonding
Ca
P
Ionic Bonding
+2
Ca
P
Ionic Bonding
+2
Ca
Ca
P
Ionic Bonding
+2
Ca
Ca
P
-3
Ionic Bonding
+2
Ca
P
Ca
P
-3
Ionic Bonding
+2
Ca
P
+2
Ca
P
-3
Ionic Bonding
Ca
+2
Ca
P
+2
Ca
P
-3
Ionic Bonding
Ca
+2
Ca
P
+2
Ca
P
-3
Ionic Bonding
+2
Ca
+2
Ca
+2
Ca
P
P
-3
-3
Ionic Bonding
Ionic_Bonds.asf
Ca3P2
Formula Unit
Shortcut

Ca+2 P-3

Ca3P2
 Crisscross the charges to become
the subscript!!!!!!!!!!!!!!!!!!!!!!!!!
I. Properties of Ionic Compounds
a. Crystalline structure.
b. A regular repeating arrangement of ion
in the solid.
c. Structure is rigid.
Crystalline structure
Ionic Compounds
NaCl:
Ionic compounds
consist of
a lattice
of positive
and negative ions.
Lattice: three
dimensional array of
ions
Ionic properties
d. Ions are strongly bonded- because of
strong forces between ions they have
1. High melting points
2. high boiling point
3. high hardness scale
4. very rigid
5. very brittle
Ionic solids are brittle
+
+
-
+
+
+
+
-
+
+
Ionic solids are brittle
 Strong Repulsion breaks crystal apart.
- + - +
+ - + - + - +
E. Conductivity
1.Conducting electricity is allowing charges
to move.
2.In a solid, the ions are locked in place.
3. Ionic solids are insulators.
4. When melted, the ions can move around.
5. Melted ionic compounds conduct.
6. First get them to 800ºC.
7. ELECTROLYTE-Dissolved in water they
conduct. (aqueous solution)
Building Ionic Compounds
Binary compound - metallic cation bonded to nonmetallic anion
1. Oxide- When a metal is ionically bonded to Oxygen
Salt - Metal + Non-metal
Polyatomic Ions
 An ion made up of two or more atoms bonded
together that acts as a single unit with a net
charge.
Build with tabs NH4 ,OH, Write the polyatomic ion
and the charge it has.
Na(OH)- a balance compound
Mg+2(OH) –1
Mg(0H)2 a balanced compound
ACTIVITY:


MAKE TAB CUTOUTS OF THE VALENCE SHELL OF
AL,
O,
Na,
Cl,
Mg,
Ca



Bond

Build just one formula unit- remember it doesn’t exist as
one in nature – it is a crystal of many formula units where
each – is surrounded by a +
Al O
Mg O
Na Cl
Activity









Demo- Burn to Create Mg+O=MgO
Check the conductivity of:
1. NaCl- solid
2. NaCl-aqueous solution
3. Distilled water
4. Tap
5. MgO-solid
6. MgO-aqueous solution
7. use magnifying glass to view NaCl
I. Metallic Bonds
 How atoms are held together in the solid
form.
 Metals hold onto their valence electrons
very weakly.
 Think of them as positive ions floating in a
sea of electrons.
 http://www.youtube.com/watch?v=c4udBSZf
LHY
Sea of Electrons
 Electrons are free to move through the solid.
 Metals conduct electricity.
+
+ + +
+ + + +
+ + + +
Metals are Malleable
 Hammered into shape (bend).
 Ductile - drawn into wires.
Malleable
+
+ + +
+ + + +
+ + + +
Malleable
 Electrons allow atoms to slide by.
+ + + +
+ + + +
+ + + +
Video
 http://www.youtube.com/watch?v=Bjf9gMDP
47s
ALLOYS
 Alloys are solid solutions made by
dissolving metals in other metals. They
are prepared by melting the metals
together and cooling the mixture.
 The properties of alloys differ from those
of their component metals. For example
stainless steel, an alloy of iron, carbon,
chromium and nickel is stronger than iron
and more resistant to corrosion.
Name of Alloy
Composition
________________________________________
Sterling silver
silver, copper
Brass
copper, zinc, tin
Cast iron
iron, carbon
Steel
iron, carbon
Stainless steel
iron, chromium, carbon, nickle
18 Carat gold
gold, silver, copper
Pewter
tin, copper, bismuth, antimony
Plumber’s solder
lead, tin
ALLOY
 A combination of 2 metals
IV.
A.
Metallic Bonds – Properties of Metals
Metallic Bonds
1. valence electrons are delocalized
a. free to move from atom to atom
2. bond is formed by the attraction of
metal cations for the moving electrons
3. “electron sea model” –atoms of
metals contribute a “sea” of free
moving electrons that move from one
atom to another
Electron Sea Model for Metallic Bonds
Positive Ions Surrounded by Delocalized Electrons
B. Properties of Metals
1. moderately high melting points
2. high boiling points
3. malleable
a. can be hammered into sheets
4. ductile
a. can be drawn into wire
5. good conductors of heat and electricity
6. luster (good reflectors of light)
7. hardness and strength varies
a. greater in transition elements
C. Alloys
1. mixture of two or more elements with
metallic properties
2. types
a. substitutional – atoms of similar
size (sterling silver, brass, pewter)
b. interstitial – small holes in the
crystal filled with smaller atoms
(carbon steel)