IONIC COMPOUNDS
Sec 8.1 Forming Chemical Bonds
• The force that holds atoms together is
a chemical bond
• Valence electrons are involved in
chemical bonds
• Elements tend to react to acquire the
stable electron structure of a noble gas
(octet rule)
Formation of Positive Ions
• Positive ions form when an atom loses
one or more valence electrons in order
to obtain a noble gas formation
• A cation is a positive ion
Formation of Negative Ions
• Negative ions form when an atom gains
one or more valence electrons in order
to obtain a noble gas formation
• An anion is a negative ion formed when
an atom gains one or more valence
electrons
• 1. a force that holds two atoms together
• 2. Atoms gain more stable electron configurations by losing or
gaining electrons.
• 3. Noble gases are relatively unreactive because they have
eight electrone I n their outermost energy
•
level, which is a stable configuration.
• 4. Positive ions form when atoms lose valence electrons.
Negative ions form when valence electrons
•
are added to an atom.
•
• 5. a. gain 3 electrons (3- ion) or lose 5 electrons (5+ ion)
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b. gain 2 electrons (2- ion)
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c. lose 2 electrons (2+ ion)
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d. lose 1 electron (1+ ion)
•
• 6. Models should show that the calcium atom loses two
electrons forming Ca+2 and the bromine atom
•
gains one atom forming Br-
Section 8.2 The Formation
and Nature of Ionic Bonds
Formation of an Ionic Bond
An ionic bond is usually between a metal
cation and a non-metal anion
http://www.youtube.com/watch?v=T40sM8SXso&feature=fvwp&NR=1
Formation of an Ionic Bond
The electrostatic force that holds
oppositely charged particles together in
an ionic compound is called an Ionic
Bond
http://www.youtube.com/watch?v=xTx_D
WboEVs
Formation of an Ionic Bond
Compounds that contain ionic bonds are
called ionic compounds.
• Ionic bonds that occur between metals
and the non metal oxygen are called
oxides
Formation of an Ionic Bond
Most other ionic compounds are called
salts
Formation of an Ionic Bond
In an ionic bond the number of electrons
lost must equal the number of electrons
gained,
Consider Ca and F
Formation of an Ionic Bond
In an ionic bond the number of electrons
lost must equal the number of electrons
gained,
Ionic Compounds
Ionic Compounds
• Binary Ionic Compounds- contain only
two different elements (one metallic
cation and one nonmetallic anion).
Ionic Compounds
• Most ionic compounds are binary
• MgO is binary, CaSO4 is not binary
Why?
Properties of Ionic
Compounds
• The chemical bonds that occur
between the atoms in a compound
determine many of the physical and
chemical properties.
Crystal Lattice
• The strong attraction of positive and
negative ions in an ionic compound
result in a 3 dimensional geometric
arrangement of particles called a
crystal lattice.
Crystal Lattice
Melting point, Boiling Point,
Hardness and Color
• Ionic compounds generally have high
melting points and boiling points.
Electrolyte
• An ionic
compound whose
aqueous solution
conducts electric
current is called an
electrolyte
Lattice Energy
• The formation of ionic compounds from
positive and negative ions is always
exothermic.
Lattice Energy
• If this amount of energy is added to an
ionic compound, the bonds will break.
The energy required to separate one
mole of the ions of an ionic compound
is referred to as the Lattice Energy
• 7. Na3N
• 8. Li2O
• 9. SrF2
10. Al2S3
11. Cs2P
12. the electrostatic attraction between oppositely charged
ions
• 13. Ions form from electron transfer. Oppositely charge
electrons attract.
• 14. exist as crystals, high BP and MP, hard, rigid,
conductive when dissolved or molten but not solid.
• 15. Each ion is surrounded by oppositely charged ions.
• 16. It is the energy required to separate the ions of an
ionic compound and is the energy given off when
positive and negative ions attract.
• 17. As the ionic radius of the non-metallic ion increases,
the melting point and lattice energy decrease.
• 18. SrCl2
Section 8.3 Names and Formulas
of Ionic Compounds
• Formula Unit
•
• The simplest ratio of the ions represented in an ionic
compound.
Section 8.3 Names and Formulas of Ionic
Compounds
• Monatomic Ion
• a one-atom ion, such as Mg+2 or Br-
Names and Formulas of Ionic
Compounds
• Most transition metals and some of
those 3A and 4A can form several
different positive ions
Names and Formulas of Ionic
Compounds
• Oxidation
Number
• The charge of
a monatomic
ion is its
oxidation
number.
(sometimes called
oxidation state)
The oxidation numbers of ions are used
to determine the formulas for the ionic
compounds they form.
Writing Formulas
• Criss cross the
oxidation
numbers
• Reduce
subscripts if
possible
Polyatomic Ions
• Many ionic compounds contain
polyatomic ions, which are ions made
up of more than one atom.
• The charge given to a polyatomic ion
applies to the entire group of atoms.
Polyatomic Ions
• The polyatomic ion acts as an
individual ion.
• The chemical formula can be written
following the same rules as monatomic
ions
Polyatomic Ions
• If more than one polyatomic ion is
needed, place parentheses around the
ion and write the appropriate subscript
outside the parentheses.
• EX Mg(ClO3)2
Naming Ionic Compounds
•
•
•
•
•
Rules:
1. Name the cation first and the anion second
2. Monoatomic cations use the element.
3. Monoatomic anions take their name from the root of
the element name plus the suffix -ide.
4. Group 1A and 2A metals have only one oxidation
number. Transition metals and metals on the right
side of the periodic table often have more that one
oxidation number. the name and chemical formula
(written as a roman numeral in parentheses after the
name of the cation).
5. If the compound contains a polyatomic ion, simply
name the ion.
Naming Ionic Compounds
•
•
•
•
•
Rules:
1. Name the cation first and the
anion second
2. Monoatomic cations use the
element.
3. Monoatomic anions take their
name from the root of the element
name plus the suffix -ide.
4. Group 1A and 2A metals have
only one oxidation number.
Transition metals and metals on
the right side of the periodic table
often have more that one
oxidation number. the name and
chemical formula (written as a
roman numeral in parentheses
after the name of the cation).
5. If the compound contains a
polyatomic ion, simply name the
ion.
Naming Ionic Compounds
•
•
•
•
•
Rules:
1. Name the cation first and the
anion second
2. Monoatomic cations use the
element.
3. Monoatomic anions take their
name from the root of the element
name plus the suffix -ide.
4. Group 1 and 2 metals have only
one oxidation number. Transition
metals and metals on the right
side of the periodic table often
have more that one oxidation
number. the name and chemical
formula (written as a roman
numeral in parentheses after the
name of the cation).
5. If the compound contains a
polyatomic ion, simply name the
ion.
Old, classic or common
nomenclature
• Suffix “ic” added to the Latin name of the
element with the higher oxidation number.
• Suffix “ous” added to the Latin name of the
element with the lower oxidation number.
Section 8.4 Metallic Bonds
and
• Metallic Bond
• the attraction of a metallic cation for
delocalized electrons
•
Section 8.4 Metallic Bonds
and Properties of Metals
• Electron Sea Model
• proposes that all metal atoms in a
metallic solid contribute their valence
electrons to form a “sea of electrons”
that are not held by any specific atom
and can easilly move from one atom to
the next.
Section 8.4 Metallic Bonds
and Properties of Metals
• Delocalized Electrons
• Because they are free to move, these
electrons are called delocalized
electrons.
Section 8.4 Metallic Bonds
and Properties of Metals
Metal alloys
• Form when a metal is mixed with one or
more other elements.
• Section 8.4 Metallic Bonds and
Properties of Metals
•
• Metallic Bond
•
• Electron Sea Model
•
• Delocalized Electrons
•
24. NaNo3
25. Ca(Clo3)2
26. Al2(CO3)3
27. K2CrO4
28. MgCO3
• 29. sodium bromide
32. copper (II) nitrate
• 30. calcium chloride
33. silver chromate
• 31. potassium hydroxide
Hydrate Lab
Hydrate Lab
Barium Chloride di hydrate
• hygroscopic.