COVALENT BONDING IONIC OR COVALENT CARBON DIOXIDE CALCIUM

COVALENT BONDING

IONIC OR COVALENT? • CARBON DIOXIDE • CALCIUM CARBIDE • RUBIDIUM BROMIDE • SILICON TETRACHLORIDE • HYDROGEN SULFIDE • WATER

NOMENCLATURE CO 2 Sr 3 N 2 P 2 O 5 PCl 3 Na 2 O H 2 O KOH Li. Br N 2 O 5 SO 2

FORMULA WRITING SILICON DIOXIDE NICKEL (III) SULFIDE DIBORON TETRABROMIDE CARBON TETRACHLORIDE ALUMINUM HYDROXIDE DINITROGEN TRIOXIDE AMMONIUM CHLORIDE LEAD (IV) OXIDE

WORKSHEETS 15 MINUTES

NON-POLAR COVALENT • Two or more non-metals • Equal or almost equal sharing of electrons • Electronegativity difference of < 0. 4 EXAMPLES: N-N (3. 0 – 3. 0 = 0. 0) Cl-Br (3. 0 – 2. 8 = 0. 2)

POLAR COVALENT • Two or more non-metals • Unequal sharing of electrons • Electronegativity difference of 0. 5 to 1. 7 EXAMPLES: Cl – C (3. 0 – 2. 5 = 0. 5) O – S (3. 5 – 2. 5 = 1. 0)

IONIC Ionic compounds are the MOST polar. The elements involved in an ionic bond always have a large difference between their respective electronegativity values. This large difference results in the “transfer” of an electron. The element “giving” the electron takes on a positive charge while the element “taking” the electron takes on a negative charge.

SHOWING POLARITY • One end has a partial positive charge (the less electronegative atom) and the other has a partial negative charge (the atom that is holding on to the electrons) • Represented by: δ+ and δ- (in the Lewis diagram) – these are called dipoles – they cause attraction between molecules

DETERMINING POLARITY To determine the polarity of a compound, a series of steps must be taken: 1) Represent the compound using Lewis dot structures. 2) Understand that EACH bond will have a different polarity. The final polarity of a compound is determined as the sum of each individual polarity created by the bonds. The shape of the molecule is also a factor.

• Look up the electronegativity of each element. If the difference between the electronegativity for the bonded elements is less than 0. 4, it is non-polar. If the difference is 0. 5 to 1. 7, it is polar. The MORE electronegative end of the bond has a negative charge, while the LESS electronegative end of the bond has a positive charge.

LEWIS DIAGRAM STEPS 1. Count number of valence electrons in all atoms. 2. Draw the central atom(s) with its/their valence electrons –always the least electronegative (exception - Never H). 3. Draw single bonds between outer atoms and central atom(s). Determine available electrons (total valence – (2×# single bonds). 4. Arrange remaining electrons in pairs around the outside atoms first, the central atom second. 5. If necessary to complete the octet on the central atom, move lone pairs from outer atoms to form multiple bonds.

LEWIS STRUCTURE REVIEW H 2 O CF 4 CO 2 CCl 4

POLARITY EXAMPLES HCl CO 2 CCl 4 H 2 O