Covalent Bonds Electrons are shared

How do you identify a covalent formula? All Nonmetals in formula How do you identify a covalent formula?

Another name for a covalent compound Molecular compound

To get the configuration of a noble gas Why do atoms form bonds?

Linear Shape of all diatomics?

Pyramid Shape of NH3, NF3, PH3, etc?

Bent Shape of H2O, H2S, H2Se, etc.?

How do you make a Lewis Dot Structure? Arrange the symbols Count up the valence electrons Distribute the valence electrons, starting with the bonding pairs – single bonds Tests How do you make a Lewis Dot Structure?

:N:::N: H : H:C:H :   H :O::O: :   :Cl: :O::C::O: : : : :Cl:C:Cl:  : : : H:F: :Cl:  :

Tetrahedral Shape of CH4, CCl4, etc.?

Has poles – the ends are different! Polar

Electron cloud is NOT symmetric. Separation of charge. Polar

Electronegativity Difference is 0.5 to 1.7 Polar

No poles. Ends are the same. Nonpolar

Electron cloud is symmetric. No separation of charge. Nonpolar

Even, balanced. Symmetrical

Electronegativity difference = 0 to 0.5 Nonpolar

Electronegativity difference  1.7 Ionic

Extremely polar Ionic

Formula has a metal and a nonmetal Ionic

Polar. Water is bent. The O end is a bit negative & the H end is a bit positive.

Results from attractions between nucleus on 1 atom & electrons on another atom. Bonding

releases energy - exothermic Making a bond …

Absorbs energy - endothermic Breaking a bond …

Covalent Compounds are Molecular compounds. Covalent Compounds are

Triple Bond N2

Double Bond O2

When bonds are made, energy is … released. When bonds are made, energy is …

When bonds are broken, energy is … absorbed. When bonds are broken, energy is …

If something exists, it is stable. Stability

As the energy of a system , the stability generally … increases. As the energy of a system , the stability generally …

As the energy of a system , the stability generally … decreases. As the energy of a system , the stability generally …

System releases energy. Its energy level goes down. Exothermic

Properties of Molecular Substances Soft Low melting point & low boiling point Does not conduct electricity in any phase Does not dissolve in water React slowly Properties of Molecular Substances

Electrons are shared equally between the two atoms Nonpolar Bonds

Molecule must contain polar bonds and they must be arranged asymmetrically. Molecular Polarity

Molecular Polarity Depends on the shape (Bent & Pyramidal are polar Linear & tetrahedral, polarity depends on composition.) Molecular Polarity

Nonpolar Molecules Noble gas atoms (kickballs) Diatomics of the form A2 (footballs) Larger molecules that have high symmetry Nonpolar Molecules

Diatomics of the form AB Larger molecules that have low symmetry Polar Molecules

Nonpolar Molecules Weak Intermolecular Forces (Dispersion or Van der Waals) Low boiling points & melting points Tend to be gases Nonpolar Molecules

Polar Molecules Intermolecular Forces are Dipole-dipole forces Stick together easier than nonpolar molecules Polar Molecules

Coordinate Covalent Bond Covalent bond where both electrons in the bond are donated by 1 atom. Coordinate Covalent Bond

Coordinate Covalent Bond + H H:N:H H:N:H H .. .. + H+  .. .. Coordinate Covalent Bond

Coordinate Covalent Bond Both electrons in the bond are donated by the same atom. Coordinate Covalent Bond

Compound that exhibits both covalent & ionic bonding Compound that contains a polyatomic ion. Compound that exhibits both covalent & ionic bonding

How to calculate the polarity of a bond Subtract the electronegativities of the 2 atoms. How to calculate the polarity of a bond

Van der Waals forces Or dispersion forces. Occur between nonpolar molecules. Weakest intermolecular force. Strength increases with size of molecule. Van der Waals forces

Occurs between polar molecules. Intermediate intermolecular force. Dipole-dipole forces

Occurs between molecules containing H-F, H-O, or H-N bonds. Strongest intermolecular force. Leads to unusually high boiling points. Hydrogen Bonding