Covalent Bonds Part 2

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Information about Covalent Bonds Part 2

Published on April 14, 2008

Author: itamarita1984

Source: slideshare.net

Covalent Bonds Part 2

When two atoms have a covalent bond, the valence orbital of one atom overlaps or merges with the valence orbital of another atom Bonding orbital localized region where bonding electrons can most likely be found

When two atoms have a covalent bond, the valence orbital of one atom overlaps or merges with the valence orbital of another atom

Bonding orbital

localized region where bonding electrons can most likely be found

Single covalent bonds (one bonding pair) Occurs when electron pair is shared in area centered between two atoms Results if atomic orbitals overlap end to end Sigma bonds form with: Overlap of s-orbital and s-orbital Overlap of s-orbital and p-orbital Overlap of p-orbital and p-orbital Sigma bonds ( σ )

Single covalent bonds (one bonding pair)

Occurs when electron pair is shared in area centered between two atoms

Results if atomic orbitals overlap end to end

Sigma bonds form with:

Overlap of s-orbital and s-orbital

Overlap of s-orbital and p-orbital

Overlap of p-orbital and p-orbital

 

 

 

Multiple Bonds Double Bond Two bonding pairs of electrons Consist of a sigma bond and one pi bond Triple Bond Three bonding pairs of electrons Consist of a sigma bond and 2 wo pi bonds

Double Bond

Two bonding pairs of electrons

Consist of a sigma bond and one pi bond

Triple Bond

Three bonding pairs of electrons

Consist of a sigma bond and 2 wo pi bonds

Pi bonds ( ∏ ) Formed when parallel orbitals overlap to share electrons Electrons shared in a pi bond occupy the space above and below the line that represents where the two atoms are joined together Double and triple bonds consist of a sigma bond and one or two pi bonds

Formed when parallel orbitals overlap to share electrons

Electrons shared in a pi bond occupy the space above and below the line that represents where the two atoms are joined together

Double and triple bonds consist of a sigma bond and one or two pi bonds

 

 

 

Bond Strength Recap: How are covalent bonds formed Attractive and repulsive forces Covalent bond broken when balance upset Bond strength determined by different factors

Recap: How are covalent bonds formed

Attractive and repulsive forces

Covalent bond broken when balance upset

Bond strength determined by different factors

Bond length The distance from the center of one nucleus to the center of the other nucleus of two bonded atoms during the point of maximum attraction Determined by: Size of atom Number of electrons shared

The distance from the center of one nucleus to the center of the other nucleus of two bonded atoms during the point of maximum attraction

Determined by:

Size of atom

Number of electrons shared

Shared Pairs… INCREASE the number of shared pairs of electrons  DECREASE bond length Triple bond has shorter bond length than single bond length Single bonds are weaker than double bonds, which are weaker than triple bonds

INCREASE the number of shared pairs of electrons  DECREASE bond length

Triple bond has shorter bond length than single bond length

Single bonds are weaker than double bonds, which are weaker than triple bonds

Energy in Bonds When bond is formed  E released When bond is broken  E is required Bond Dissociation Energy Amount of energy required to break a specific covalent bond Breaking bonds requires adding energy Positive value kJ/mol Sum of bond dissociation energies for all bonds in a compound determines the chemical potential energy available in a molecule of that compound

When bond is formed  E released

When bond is broken  E is required

Bond Dissociation Energy

Amount of energy required to break a specific covalent bond

Breaking bonds requires adding energy

Positive value kJ/mol

Sum of bond dissociation energies for all bonds in a compound determines the chemical potential energy available in a molecule of that compound

Relationship Between Bond Energy and Bond Length The closer atoms are bonded together, the more energy is required to break the bond DECREASE bond length = INCREASE bond dissociation energy Which of the following has the greatest bond energy? Which has the least? F 2 , O 2 , N 2

The closer atoms are bonded together, the more energy is required to break the bond

DECREASE bond length = INCREASE bond dissociation energy

Which of the following has the greatest bond energy? Which has the least?

F 2 , O 2 , N 2

Total Energy change of chemical reaction determined by the energy of bonds broken and formed Endothermic Reactions Greater amount of energy required to break the existing bonds in the reactants than is produced in the new bonds formed in the products Exothermic Reactions More energy is released forming new bonds in the products than is required to break the bonds in the initial reactants

Total Energy change of chemical reaction determined by the energy of bonds broken and formed

Endothermic Reactions

Greater amount of energy required to break the existing bonds in the reactants than is produced in the new bonds formed in the products

Exothermic Reactions

More energy is released forming new bonds in the products than is required to break the bonds in the initial reactants

Naming Molecules Binary molecular compound Covalently bonded compound containing only two different elements Composed of 2 different nonmetals No ions or metals

Binary molecular compound

Covalently bonded compound containing only two different elements

Composed of 2 different nonmetals

No ions or metals

Naming Binary Molecular Compounds The first element in the formula is always named first, using the entire element name The second element in the formula is named using the root of the element and adding the suffix – ide Prefixes are used to indicate the number of atoms of each type that are present in the compound Exception: first element in formula never uses mono - Drop final letter in the prefix when the element name begins with a vowel Hydrogen bonded to 7A halogens (drop mono)

The first element in the formula is always named first, using the entire element name

The second element in the formula is named using the root of the element and adding the suffix – ide

Prefixes are used to indicate the number of atoms of each type that are present in the compound

Exception: first element in formula never uses mono -

Drop final letter in the prefix when the element name begins with a vowel

Hydrogen bonded to 7A halogens (drop mono)

1 - mon(o) 2 - di 3 - tri 4 - tetr(a) 5 - pent(a) 6 - hex(a) 7 - hept(a) 8 - oct(a) 9 - non(a) 10 - dec(a) Prefixes H - hyd C - carb N - nitr P - phosph As - arsen O - ox S - sulf Se - selen F - fluor Cl - chlor Br - brom I - iod Nonmetal roots

1 - mon(o)

2 - di

3 - tri

4 - tetr(a)

5 - pent(a)

6 - hex(a)

7 - hept(a)

8 - oct(a)

9 - non(a)

10 - dec(a)

H - hyd

C - carb

N - nitr

P - phosph

As - arsen

O - ox

S - sulf

Se - selen

F - fluor

Cl - chlor

Br - brom

I - iod

Practice problems: CO P 2 O 5 CCl 4 As 2 O 3 NF 3 SO 2 Carbon monoxide Diphosphorus pentoxide Carbon tetrachloride Diarsenic trioxide Nitrogen trifluoride Sulfur dioxide

CO

P 2 O 5

CCl 4

As 2 O 3

NF 3

SO 2

Carbon monoxide

Diphosphorus pentoxide

Carbon tetrachloride

Diarsenic trioxide

Nitrogen trifluoride

Sulfur dioxide

More practice… H 2 O NH 3 N 2 H 4 N 2 O NO Di hydrogen monoxide Nitrogen trihydride Dinitrogen tetrahydride Dinitrogen monoxide Nitrogen monoxide Water Ammonia Hydrazine Nitrous oxide Nitric oxide

H 2 O

NH 3

N 2 H 4

N 2 O

NO

Di hydrogen monoxide

Nitrogen trihydride

Dinitrogen tetrahydride

Dinitrogen monoxide

Nitrogen monoxide

Water

Ammonia

Hydrazine

Nitrous oxide

Nitric oxide

Naming Acids Molecules can be put in solution (water) and they make acids If compound releases H+ ions when put in water solution, it is an ACID Only name acids if molecule is put in water!!! Two types Binary Acids Oxyacids

Molecules can be put in solution (water) and they make acids

If compound releases H+ ions when put in water solution, it is an ACID

Only name acids if molecule is put in water!!!

Two types

Binary Acids

Oxyacids

Binary Acids Hydrogen + one other element Sometimes there are more than 2 elements To name hydrogen, use prefix Hydro- Root (or form of root) of the second element followed by suffix –ic If there are more than 2 elements involved, the root of the second part of the name is the root of the polyatomic ion that acid contains Add the word acid to the end Example: HCN Hydrocyanic acid Example: HCl Hydrochloric acid

Hydrogen + one other element

Sometimes there are more than 2 elements

To name hydrogen, use prefix Hydro-

Root (or form of root) of the second element followed by suffix –ic

If there are more than 2 elements involved, the root of the second part of the name is the root of the polyatomic ion that acid contains

Add the word acid to the end

Example: HCN

Hydrocyanic acid

Example: HCl

Hydrochloric acid

Oxyacids Acids thant contain OXYANION What is an oxyanion? Polyatomic ion that contains oxygen First: Determine anion present Use a form of the root of the anion Add suffix Anion suffix –ate….oxyacid suffix= - ic Anion suffix –ite….oxyacid suffix= -ous Add the word acid Example:HNO 3 Oxyanion: nitrate NO 3 - Oxyacid name: nitric acid Example:HNO 2 Oxyanion: nitrite NO 2 - Oxyacid: nitrous acid

Acids thant contain OXYANION

What is an oxyanion?

Polyatomic ion that contains oxygen

First: Determine anion present

Use a form of the root of the anion

Add suffix

Anion suffix –ate….oxyacid suffix= - ic

Anion suffix –ite….oxyacid suffix= -ous

Add the word acid

Example:HNO 3

Oxyanion: nitrate NO 3 -

Oxyacid name: nitric acid

Example:HNO 2

Oxyanion: nitrite NO 2 -

Oxyacid: nitrous acid

Practice HI HClO 3 H 2 SO 4 H 2 S HClO 2 Hydroiodic acid Chloric acid Sulfuric acid Hydrosulfuric acid Chlorous acid

HI

HClO 3

H 2 SO 4

H 2 S

HClO 2

Hydroiodic acid

Chloric acid

Sulfuric acid

Hydrosulfuric acid

Chlorous acid

Writing formulas Write the symbols for the elements in the order mentioned in the name. Write subscripts indicated by the prefixes. If the first part of the name has no prefix, assume it is mono-. Prefixes  tell you SUBscripts fro each element

Write the symbols for the elements in the order mentioned in the name.

Write subscripts indicated by the prefixes. If the first part of the name has no prefix, assume it is mono-.

Prefixes  tell you SUBscripts fro each element

Writing Formulas for Binary Covalent Compounds: Examples nitrogen dioxide NO 2 diphosphorus pentoxide P 2 O 5 xenon tetrafluoride XeF 4 sulfur hexafluoride SF 6 * Second element in ‘ide’ from mono 1 * Drop –a & -o before ‘oxide’ deca 10 nona 9 octa 8 heptaa 7 hexa 6 penta 5 tetra 4 tri 3 di 2

Air Pollution Class Work Many common air pollutants for acids when dissolved in a water solution Complete the following table HNO 3 NO 2 Carbonic acid SO 2 Name of Acid Formula of Acid Name of Molecule Formula of Pollutant

Many common air pollutants for acids when dissolved in a water solution

Complete the following table

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