IONIC & METALLIC BONDS
Mr. O’Brien (SFHS)
Chapter 8
standard 2AC&E
Review
Formation of cations & anions
• What do all elements want to be like?
Checking for Understanding
Identify whether the following will form an
anion or a cation and write their ionic symbol.
Potassium Beryllium Phosphorus
Oxygen Fluorine
– Noble Gases (full outer shell of 8ve)
• What will all other elements do to be
like NG?
– Gain, lose, or share ve.
– Atoms turn into ions.
• How do atoms become cations?
• How do atoms become anions?
– When an atom loses 1 or more
valence é
– When an atom gains 1 or more
valence e, it becomes an anion.
Sodium (Atom)
11p+ 11e- = 0
Chlorine (Atom)
17p+ 17e- = 0
Sodium (Cation)
11p+ 10e- = +1
Na+1
Chlorine (Anion)
17p+ 18e- = -1
Cl-1
Review
Electronegativity & Ionization Energy
•non-metals
•gain valence electrons
•high electronegativity (attractive)
Checking for Understanding
What type of elements form cations?
Explain using your knowledge of IONIZATION
ENERGY why cations form (+) ions.
What type of elements form anions?
Explain using your knowledge of
ELECTRONEGATIVYTY why anions form (-)
ions.
•metals
•lose valence electrons
•low ionization energy (weak)
Formation & Properties of an
IONIC BONDS (std.2A&C)
Key Terms
Electrostatic force
(attraction between cations (+) and anions (-)
Salt
Solid ionic compounds
What are ionic bonds composed of?
– Metal (cations) and nonmetal (anions)
elements
How are ionic bonds formed?
– by the transfer of valence electrons
– metal atoms will lose their valence
Checking for Understanding
electrons TO the more attractive
How can you tell these compounds
nonmetal atoms.
are Ionic bonds?
– These ions are then held together by NaCl, MgCl , CaO, Li N, Na (SO )
2
3
2
4
electrostatic force
Explain the ratios of ions in each
compound above.
1:1
Na+1:Cl-1
Formation & Properties of an
IONIC BONDS (std.2A&C)
What shape is are ionic solids?
– Crystal Lattice (cubic) structure.
– Repeating patterns of cations (+) and
anions (-).
Why does a Crystal Lattice work?
•
There’s enough space between ions so they
don’t repel.
How do we measure the strength of the crystal
lattice?
– Lattice energy
(energy required to separate ions of an ionic compound)
HONORS:
Factors of Lattice Energy:
1. Size of ions
(smaller ions have more lattice energy)
2. Charge of ions:
(ionic bonds with ions of larger oxidation numbers
(charges), have more lattice energy)
Checking for Understanding
What pattern do you notice in the lattice energies
of sodium salts?
Can you predict the order of the following
potassium salts from strongest to weakest salt.
KI, KBr, KF, KCl
Formation & Properties
of Ionic Bonds (std.2A&C)
What are Properties of ionic bonds:
•
•
•
What are Electrolytes???
Liquid solution that contains FREE ions
that move randomly in the solution.
This solution (electrolyte) can now conduct
electricity because ions are able to move.
Hard, rigid, and brittle crystal solids
As solids high melting/boiling points
Conductive when dissolved in liquids,
(the bonds break apart into ions forming electrolytes)
NO CURRENT
Ions “STUCK”
FYI
Sugar (non-ionic) melts at 135oC
CURRENT
Ions move in liquid
and carry electricity
Lewis Dot Structures
for Ionic Bonds (std.2E)
Why are Lewis Dot Structures used?
–
To show valence electrons!
How to draw Lewis Dot Structures for Ionic
Bonds?
1. Draw e dot structures for each atom.
2. The more electronegative atom will
“steal” an electron from the other. Move
the electrons.
3. Write charges above the ions.
 note: anions will have octets while the
cations have no ve
(figure 1) Note that atoms are neutral when they
contain their valence electrons. When they lose or
gain valence electrons, then charges must be
written. What’s wrong with the animation below?
Can opposite charged ions be next to each other?
Checking for Understanding
Draw the Lewis Dot Structure for each
LiCl
Li2O
MgF2
AlF3
(See above)
Writing Ionic Formulas (HONORS)
What are formulas?
– Subscripts show the ratio of ions in
each compound.
Examples of Writing Formulas
How do you make an ionic
formula?
– Write cation (symbol & charge)
– Write anion (symbol & charge)
Total charges of ions
(cations &anions)
must EQUAL zero.
Use subscripts
to show amount of ion for each
Use parentheses
to group polyatomic ions together.
Magnesium & Oxygen
Mg+2 O-2 = charges equal zero
MgO
Aluminum & Fluorine
Al+3 F-1 ⇨ Al+3 F(-1)3
AlF3
Calcium & Nitrate
Ca+2 NO3-1 ⇨ Ca+2 NO3(-1)2
Ca(NO3)2
Checking for Understanding
Write the formula for the following?
(Lithium &Oxygen) (Gallium& Bromine)
(Potassium & Sulfate) (Ammonium & Sulfur)
Writing Names of Ionic Compounds (honors)
How to write names of simple ionic compounds?
1. Write name of cation
Example of Simple Ionic Comounds:
NaCl (sodium chloride)
2. Write name of anion
MgO (magnesium oxide)
3. Change ending of anion to “ide”
How to write names with polyatomic ions?
1. Write name of cation
Example with Polyatomic ions:
NaNO3 (sodium nitrate)
2. Write name of polyatomic ion
Mg3(PO4) (magnesium phosphate)
How to write names using transition metals?
1. Write name of cation
2.
3.
Figure out its’ oxidation number and write roman numeral.
Write name of anion (if anion from Periodic Table, write “ide”
ending.
Key Term
Example with Transition metals:
CuNO3 (copper (I) nitrate)
Cu(NO3)2 (copper (II) nitrate)
Oxidation Number
Charge of an ion
Checking for Understanding
Write the names for the following?
Li2O
MgCl2
Al2S3
Na2SO4
NH4Cl
H2O2
Be3(PO3)
Metallic
Bonds
(std.2A)
What types of elements form Metallic
Bonds?

Formed from ONLY metal atoms (cations).
How are valence electrons exchanged in a
Metallic Bond?
 Metal atoms contribute their valence
electrons (delocalized electrons) to the
group.
If the metal atoms are all cations, how are they
then held together?
•
(figure 1) Metallic bonds in a sample of silver. Note
the silver cations can tolerate each other because
they are attracted to the “roaming” valence electrons
(delocalized electrons).
Key Term
Electron Sea Model
Like water in a sea, valence electrons of
metal atoms in a metallic bond are always
in constant motion
Metal atoms are attracted to the roaming
Delocalized Electrons
(figure 2&3) Animations showing the movement of
delocalized valence electrons. Note that valenece
electrons are not held by any specific atom and can
easily move form one atom to the next.
Metallic Bonds
(Std.2A)
What are a few properties of
Metallic Bonding?
–
–
–
–
–
Malleable (bendable)
Ductile (drawn into wire)
(figure 1) Because the
metal
cations are attracted
Good conductors
to the delocalized electrons
they can be bent or moved
Lustrous (shiny)
and still be part of the metal
bond.
High melting/boiling points
(figure 4) Data table listing
various melting points of metallic
bonds. Note conventional ovens
can reach limits of 250oC
(figure 3) Since delocalized can
move anywhere they can carry
electricity across the metal bonds.
(figure 2) Delocalized electrons
absorb light energy (photons)
and also release them. Thus
metals look shiny.