Bonding
Chapters 6 and 7
___________________the force that holds two atoms together. A mutual attraction between the nuclei and the valence
electrons of different atoms that binds the atoms together.
Bonds forms to _________________ potential energy in order to become stable.
Review: Valence electrons are the electrons in the highest energy level. These electrons are found in the
________________ or ________________________________________
______________- 8 valence electrons- this makes an atom stable.
_____________- positive ion- loses electrons (metals)
____________ - negative ion- gains electrons (nonmetals)
_____________– a chemical combination of two or more elements in a fixed proportion.
3 major types of bonds:
____________- occurs between metals and nonmetals
“transfer of electrons”
___________- occurs between nonmetals and nonmetals “sharing of electrons”
____________- occurs between metals and metals
“sea of electrons”
Ionic Bonding
___________________- a compound that is composed of oppositely charged ions attracted to one another. The ions
combine so that the number of positive and negative charges are equal. The force of this attraction holds the ions
together.
Examples:
Properties of ionic compounds:
1. ______________ at room temp
2. _____________ melting points
3. ___________
4. ___________
5. ________________________________
6. ____________________________ when melted or dissolved ( not in the solid form)
7.
___________________________ a substance that conducts electricity when dissolved in water.
The ions in an ionic compound are arranged in a crystal lattice structure. The energy required to break this structure is
called the __________________. The more negative this value, the stronger the bonds in the crystal. The negative
value signifies that the formation of the ionic bond was __________________ ( energy was released).
The formula for an ionic compound uses the _______________________of subscripts. This lowest ratio of subscripts is
called the _____________________formula.
Subscripts are used in the formula to _____________________ on the positive and negative ions. A compound must be
neutral.
The simplest ratio of subscripts for an ionic compound is called a _____________________.
A polyatomic ion is a group of atoms __________________________________ that is ionically bond to another ion. The
charge of the polyatomic ion applies to the entire group of atoms in the ion.
Examples:
Reason these definitions: monatomic ion, monatomic cation, monatomic anion, oxyion, oxyanion
The oxidation number for an ion in an ionic compound is equal to the charge of the ion.
You are responsible for the element symbols and charges from the Periodic Table. A Periodic Table will always be
furnished for any test or quiz.
Chemical Formulas indicate the relative number of atoms in a compound. In an ionic compound, a chemical formula
represents one _________________________.
Examples:
Writing Formulas:
The Cation is written first and the Anion is written second. Subscripts are used to balance the charges.
Because some elements can vary its charge, the roman numeral used in the name will signify the charge.
DO NOT use roman numerals when writing chemical formulas.
( ) parenthesis are only used around a polyatomic ion when more than one is needed in the formula.
Naming Ionic Compounds or Nomenclature of Ionic Compounds
The Cation will keep the name of the element from the Periodic Table and the anion will change its name to use
the –ide suffix.
Polyatomic anions will not change names.
Roman numerals should be used in the name when writing elements that are capable of forming more than one
charge. You will only be responsible for the elements that are listed on the ion sheet. This is only a partial list to simply
the naming process. The Stock System or Method uses the _____________naming system.
Metallic and Covalent Bonds
_________________________________________- a compound contains the same elements in the same proportions
regardless of the size of the sample
______________________________________- if 2 compounds contain the same 2 elements, the mass of the elements
can expressed as ratios of whole numbers—translated this allows the use of subscripts which can differentiate between
compounds that contain the same elements- an example could be: CO2 and CO.
______________________________ the force that holds two atoms together. A mutual attraction between the nuclei and
the valence electrons of different atoms that binds the atoms together.
Bonds forms to ____________________________potential energy in order to become stable.
______________________________________atoms tend to gain, share or lose electrons in order to achieve an octet.
3 major types of bonds:
____________________- occurs between metals and nonmetals
“transfer of electrons”
____________________- occurs between nonmetals and nonmetals “sharing of electrons”
_____________________-occurs between metals and metals
“sea of electrons”
Metallic Bonds
___________________________ results from the attraction between metal atoms and the surrounding sea of electrons.
Properties: 1.___________________________________________
2. __________________________________________
3. _________________________________
4. ________________________________
___________________________________ is different between the metals and depends on the nuclear charge and number
of electrons involved.
Strong bond requires more energy to vaporize the metal.
The difference between ionic and Covalent bonding can be predicted by comparing
Electronegativities.
> 1.8 ionic
0.3-1.7 polar covalent
< nonpolar covalent
Sample problems:
Covalent Bonds
Covalent Bonding is defined as the sharing of electrons between atoms.
General Rule: Nonmetals bond to Nonmetals Covalently
Molecules only contain covalent bonds
Covalent Bond- is a bond that is formed when 2 electrons are shared or formed from a shared pair
Polar Covalent- electrons are shared unequally
Results in one electrons being slightly positive and one electrons being slightly negative
Nonpolar Covalent- electrons are shared equally
Single Bonds- one shared pair of electrons
Double bonds- 2 shared pairs of electrons
Triple bonds- 3 shared pairs of electrons
Properties of Covalent Bonds:
Compounds are gases, liquids, low melting solids
Nonconductive ( nonelectrolytes- few exceptions to the rule)
nonelectrolyte- a substance that does not conduct electricity when dissolved in water
Less soluble in water than ionic compounds
Examples: sugar, gasoline, oil, fat, plastics, propane gas, methane gas
Chemical Formula- a shorthand method using subscripts and symbols of elements
Molecular Formula- tells the number and type of atoms in a molecule (may not be the lowest ratio and must have covalent
bonds)
Structural Formula- indicates the kind, number, arrangement and bond types in a molecule
DRAW EXAMPLES: Whenever I draw a structure you need to draw it on your note sheet-it must be important
Multiple Bonds: double and triple bonds Strength: T>D>S
Length: S>D>T
(Multiple bonds can change compounds properties and are formed when there are not enough valence electrons)
S =N-A
S= shared electrons
N= needed electrons
A= available electrons
(N will always be 8 for every element except hydrogen. Hydrogen will always be 2)
Draw all examples: Use your paper and keep these together be sure to put the charge on the structures for the polyatomic
ions.
Resonance- the bonding cannot be represented by a single structural formula
Naming Binary Molecular Compounds: are compounds that are inorganic and contain 2 elements that are covalently
bonded. Uses prefixes: mono-1, di-2, tri-3, tetra-4, penta-5, hexa-6, hepta-7, octa-8, nona-9, deca-10
Rules:
1st element uses the name from the Periodic Table
Never uses the prefix mono
2nd element uses the suffix –ide
Must have a prefix
Always has the higher electronegativity (most attractive)
Examples:
Intramolecular forces are the forces of attraction that are within the molecule, formula unit or atom.
Intermolecular forces occur between two molecules. These are weaker than any of the intramolecular forces or bonds
Three major types of intermolecular forces: (IMF stands for Intermolecular Force)
1. Dispersion forces (London Dispersion Force): are caused by the attraction of temporary dipoles.
A temporary dipole is when a nonpolar molecule has a shift of the electrons and becomes slightly polar. This polarity is
temporary and is weak. “Temporary is a very important word” Example- can effect solubility of oxygen in water.
2. Dipole - Dipole force- are caused by permanent dipoles
A permanent dipole is formed when the molecule contains at least one polar bond. The slightly positive
end of one molecule is attracted to the slightly negative end of another molecule. This attraction is stronger than a
dispersion force only if the substances are very similar in size.
In a polar molecule the element that has the higher electronegativity is slightly negative and the element with the lower
electronegativity is slightly positive.
Electronegativity is the element attractiveness or the ability to attract an electron
In the above example the chlorine is slightly negative and the hydrogen is slightly positive.
Carbon dioxide contains polar bonds, but the molecule is nonpolar. Because Carbon dioxide is nonpolar, it has no
IMF. This is the reason that Carbon dioxide is a gas at room temperature
The shape of the carbon dioxide molecule cancels out the polarity.
3.Hydrogen Bond- is not a bond but an attraction between molecules.
One special type of dipole –dipole attraction. It can only occur between hydrogen and Fluorine, Oxygen or Nitrogen
(FON) This is generally a very strong intermolecular attraction
In the drawing of ice, label the covalent bond and the Hydrogen bond. Label hydrogen as a slightly positive charge and
oxygen as a slightly negative charge. Which one has the higher electronegativity?
Why does ice float? The space pockets that form between the molecules.
Exceptions to the octet ruleThere are a few compounds that will form a compound with more than an octet or less than an octet. These
compounds are exceptions to the octet rule.
1. many compounds of Boron do not follow the octet rule. Boron ands Beryllium are both so reactive that they may
deviate from the rule.
2. some form compounds with more than eight electrons. This may happen in the third period and heavier elements.
The use of the d sublevel allows the atoms to achieve more than an octet.
3. a molecule with an odd number, may not achieve an octet.
VSEPR model- valence shell electron pair repulsion model- useful in predicting the geometric shapes of molecules
formed from nonmetals
It minimizes the electron repulsions and bonding and nonbonding pairs are positioned as far apart as possible.
Review page 200 of geometric shapes involved.
Hybrid OrbitalsWhen 2 atoms bond their orbitals mix to form a hybrid orbital. This orbital has a combination of the properties of
the atomic orbitals that form them.
Shape
hybrid orbital
Linear
sp
Triangular planar
sp2
Tetrahedral
sp3
Triangular pyramidal sp3
Bent
sp3
3
( the sp orbital is used when 4 pairs of valence electrons are involved)
_____________________________are the forces of attraction that are within the molecule, formula unit or atom.
________________________ occur between two molecules. These are __________________ than any of the intramolecular forces
or bonds
Three major types of intermolecular forces: (IMF stands for Intermolecular Force)
1. _______________________ (London Dispersion Force): are caused by the attraction of temporary dipoles.
A _______________________________ is when a nonpolar molecule has a shift of the electrons and becomes slightly
__________________. This polarity is temporary and is weak. “Temporary is a very important word”
Example- can
effect solubility of oxygen in water.
2. __________________________________________- are caused by permanent dipoles
____________________________________ is formed when the molecule contains at least one polar bond. The
slightly positive end of one molecule is attracted to the slightly negative end of another molecule. This attraction is stronger than a
dispersion force only if the substances are very similar in size. DRAW the example and label + and - sides
In a polar molecule the element that has the ___________________electronegativity is slightly negative and the element with the
___________________electronegativity is slightly positive.
___________________________________ is the element attractiveness or the ability to attract an electron
In the above example the chlorine is slightly negative and the hydrogen is slightly positive.
Carbon dioxide contains polar bonds, but the molecule is nonpolar. Because Carbon dioxide is nonpolar, it has no IMF. This is
the reason that Carbon dioxide is a gas at room temperature.
DRAW example:
The shape of the carbon dioxide molecule cancels out the polarity.
3___________________________- is not a bond but an attraction between molecules.
One special type of dipole –dipole attraction. It can only occur between ________________ and ____________, ______________or
________________ (FON) This is generally a very strong intermolecular attraction
In the drawing of ice, label the covalent bond and the Hydrogen bond. Label hydrogen as a slightly positive charge and oxygen as a
slightly negative charge. Which one has the higher electronegativity?
Why does ice float? The space pockets that form between the molecules.
Exceptions to the octet ruleThere are a few compounds that will form a compound with more than an octet or less than an octet. These compounds are
exceptions to the octet rule.
1. many compounds of Boron do not follow the octet rule. Boron ands Beryllium are both so reactive that they may deviate
from the rule.
2.
some form compounds with more than eight electrons. This may happen in the third period and heavier elements. The use of
the d sublevel allows the atoms to achieve more than an octet.
3.
a molecule with an odd number, may not achieve an octet.
VSEPR model- valence shell electron pair repulsion model- useful in predicting the geometric shapes of molecules formed from
nonmetals
It minimizes the electron repulsions and bonding and nonbonding pairs are positioned as far apart as possible.
Review page 200 of geometric shapes involved.
Hybrid OrbitalsWhen 2 atoms bond their orbitals mix to form a hybrid orbital. This orbital has a combination of the properties of the atomic
orbitals that form them.
Shape
hybrid orbital
Linear
sp
Triangular planar sp2
Tetrahedral
sp3
Triangular pyramidal
sp3
Bent
sp3
3
( the sp orbital is used when 4 pairs of valence electrons are involved)
The book does a good job on this subject. I suggest reading chapter 6 in the textbook..