8.1 Covalent Bonds

Molecular compounds = 2 non metals that share 1 or more

pairs of electrons…

group is electrically neutral.

Draw the dot structure for CF4

A dash shows a molecular bond and represents 2 electrons

How is water (H2O) different from sodium chloride (NaCl)?

Review Bond Types:Copy into powerpoint notes.

IONIC: Metal and Non Metal ions. Electrons jump from metal to non metal

to make “magnets”.METALLIC: Metal and Metal ions.

Electron sea floats between positive ions.CoVALENT: Non Metal and Non Metal

atoms (Not ions). Share electrons.

IONIC review: NaCl=Formula Unit=lowest ratio of ions in an ionic compound -atoms gained or lost e- to

form ions that are electrostatically bonded to each other (metal)

H2O =Molecular Formula= (Nonmetals) molecule

atoms share electrons to form stable noble gas configurations (atoms

don’t form ions but still follow the octet rule) H=2 electrons

Notice the octet rule H = He 2e-O=Ne 8e-

Molecular formula = shows the number and types of atoms in a

molecule

Discuss VESPER Theory and shapes of these molecules (electron pairs make 4 point pyramid). Discuss the Lewis Structures.

How is the molecular formula different from a formula unit?

Covalent Bond Ionic Bond

Sharing 2 or 3 pair of electrons

Sharing 2 pairs of electrons

Draw the compound CO2

Bond dissociation

energy = amount of

energy needed to

break a single covalent bond

The higher the BDE the

stronger and more stable the bond.

7 diatomic elements found on earth

H2, N2, O2, F2, Cl2, Br2, I2

Diatomic elements: 7,

VSEPR = valence-shell electron-pair repulsion theory. Causes

shape of molecules. repulsion between electron pairs causes molecular shapes to adjust so that the valence-electrons pairs

stay as far apart as possible(SEE p242)

Polar bonds : electron pair is shared unevenly. Causes the molecule to act

like a magnet. (the element with higher

electronegativity (p.xxx) has the electron more often and become

slightly negative)

Subtract the electronegativity of the two atoms to find the type of bond. (pg 248) Bond Type0-0.39 Nonpolar covalent0.4-1.0 Moderately polar1.0-1.9 Very Polar2.0 + Ionic or Metallic

Hydrogen Bonds – hydrogen bonded to an atom with a high

electronegativity is weakly bonded to a nearby molecules

unshared electrons

Bond Typep.238 table 8.3

Electronegativity Difference0.0-0.39 nonpolar covalent

0.4-1.9 polar covalent metal = Ionic

Polar molecules – a molecule that has two poles (positive and negative,

only happens with polar bonds) based on VSEPR shape

Label bond type on worksheetIdentify VSEPR shape

Identify polar molecules

POLYATOMIC IONS:Sharing too many electrons…

Polyatomic ions (molecules with a charge)

Review

Draw the compound SCl2

Draw the compound SCl2

Molecules:Covalent Sharing of Electrons