Transcript Ionic Compounds and Metals - Mrs. Paul's Chemistry Class

Ionic Compounds and Metals
Types of bonds
• A chemical bond is the force that holds
atoms together in a molecule.
• Ionic bonds form when electrons are
transferred between atoms.
• Covalent bonds form when electrons are
shared between atoms.
Electronegativity
• Electronegativity is a measure of the attraction a
bonded atom has for electrons.
• Electronegativity increases from bottom to top
and from left to right.
Formation of Ionic Bonds
• If the electronegativity difference is large
(a metal with a nonmetal) an ionic bond
will form.
• Ionic bonds are the strongest type of bond.
• Substances resulting from ionic bonds are
classified as crystalline solids.
Let’s Practice
• Identify the type of bond (ionic or covalent)
that will form between each pair of atoms.
1) Na and Cl
2) C and O
3) N and H
4) Ca and O
5) K and N
6) Mg and F
Example
Forming Ions
• When neutral atoms
gain or lose valence ean ion is formed.
• Ions are atoms with a
charge
• Cations have a positive
charge (K+, Li+)
• Anions have a negative
charge (F-, I-)
Ions forming bonds
• Cations are attracted to anions because of
opposite charges.
• “Opposites attract”
Why do ions form?
• Ions form to attain a more stable electron
configuration.
• Remember that a Noble gas configuration
is the most stable
Ne - ___ ___ ___ ___ ___
1s 2s
2p
• All Noble Gases have a full octet (8
valence e-)
Noble Gases
Why do ions form?
Na __ __ __ __ __ __
1s 2s
2p
3s
Na+ __ __ __ __ __ __
1s 2s
2p
3s
Now Na+ looks like
neon
Ne __ __ __ __ __
1s 2s
2p
• All atoms are trying to
have a Noble Gas
electron configuration
so, they will lose or
gain electrons to get
there
Why do ions form?
• F __ __ __ __ __
1s 2s
2p
F- __ __ __ __ __
1s 2s
2p
Ne __ __ __ __ __
1s 2s
2p
Review
Draw the dot notation for each element and
the charge of its ion
• N
• S
• Ba
• Li
Ionic Bonds
• Ionic bonds- the force
that holds two
oppositely (+ and -)
charged particles
together.
• Ionic compounds
contain ionic bonds
and are neutral
• Usually forms
between a metal and
a nonmetal
Forming Ionic Bonds
Forming Ionic Compounds
Write an equation showing how ionic
compounds are formed for the following
elements.
1. Na and I
2. Mg and O
3. Al and Cl
Properties of Ionic Compounds
Shape
• The Ionic bond produces
unique characteristics for
ionic compounds
• Crystals are created by
repeating patterns of
cations and anions. This
balances the forces
between the ions.
• This is called a crystal
lattice
Properties of Ionic Compounds
Physical Properties
• Electrolytes
(aqueous ions- Ions
dissolved in water)
conduct electricity
• Solid ionic
compounds DO NOT
conduct electricity
because the charges
are locked in place
Properties of Ionic Compounds
Physical Properties
• Ionic solids are strong
and hard to break
apart
• High Melting points
• High Boiling points
• Transition metals in
the crystal give the
ionic solid color.
Properties of Ionic Compounds
Physical Properties
The solid ionic crystals
are hard, rigid, and
brittle
The strong forces
between ions produce
this property
Ionic Compounds
• Ionic compounds are repeating patterns of the
cation and anion.
• The simplest ratio of ions involved is called a
formula unit.
• NaCl is the formula unit for table salt
Ions in Ionic Compounds
• Monatomic ions- ions
made of only one type
of atom (Cl-, F-, Li+)
• Polyatomic ions- ions
made of at least two
different types of ions
(OH-, NH4+)
• Cation + Anion 
Ionic Compound
Writing formulas for ionic
compounds
Binary ionic compounds contain a single
cation and anion. Remember that the
final compound must be neutral so the
charges must balance.
Ca+2
Cl-  CaCl2
Cris-Cross method
• Record the ion symbol and charge
• The # of the charge of the cation becomes
the subscript for the anion and the # of the
charge for the anion becomes the subscript
for the cation. The #1 does not have to be
recorded it is understood.
Al+3 O-2  Al2O3
Cris-Cross method
Al2O3 is the formula units for aluminum
oxide. The subscripts indicate how many
ions are needed of each in order to
balance the charges.
Try a few
•
•
•
•
Potassium and Iodide
Magnesium and chloride
Aluminum and bromide
Cesium and nitride
Naming Ionic Compounds
NaBr
• Name the cation then the anion. Cations are
always written first
• Monatomic cations always keep their name. If
the cation is an ion that may carry multiple
charges then a roman numeral is used to
indicate which charge the cation is carrying.
[Fe+3 (III) and Fe+2 (II)].
Naming Ionic Compounds
The monatomic anion’s ending is
changed to -ide. Fluorine is changed to
Fluoride.
NaBr- sodium bromide
Fe3N2 – Iron (II) nitride
Let’s practice
•
•
•
•
CaCl2
K2O
CuCl2
Fe2O3
What about Polyatomic ions?
• Al+3 and PO4-3  AlPO4
• The same rules apply, however NEVER
CHANGE A SUBSCRIPT THAT IS
ALREADY THERE.
• Polyatomic ions may also require ()
around them if there is a need for more
than one to balance the charge
Metallic Compounds
• Compounds containing only metals
• Form lattice crystals as solids
Metallic Bonds
• Metals do not give
away or take on
valence electrons.
• They do not share
electrons to make
bonds either.
• Electrons from metals
overlap and create a
sea of electrons that
bond metal atoms
Metallic Bonds
• The electrons are free to move between
atoms (delocalized electrons)
• As an electron moves from one atom to
the next it creates a cation which “bonds”
the atoms together creating a metallic
bond.
Properties of Metals
• Metals Usually have
high melting points.
• Metals usually have
high boiling points
• Why?
Properties of Metals
• Malleable- ability to
be hammered into a
thin sheet
• Ductile- ability to be
stretched into a thin
wire
• Durable-long lasting
• Why?
Properties of Metals
• Good conductors of
heat
• Good conductors of
electricity
• Why?
Properties of Metals
• Metals are strong and
hard
• Why?
Alloys
• Alloys are mixtures of
metals
• Ex: stainless steel,
brass, cast iron
• Properties of alloys
are similar to those of
its elements. Alloys
tend to be stronger
than the element