Covalent Compounds January 2015 Covalent Compounds Covalent Bond

Covalent Compounds January 2015

Covalent Compounds Covalent Bond – chemical bond that results from sharing electrons Molecule – formed when two or more atoms are bonded covalently

Naming Binary Compounds 1. First element named first 2. Second elements ending is changed to –ide 3. Use prefixes to indicate the number of each atom Examples: N 2 O – dinitrogen monoxide CCl 4 – carbon tetrachloride

Prefixes 1. Mono – 2. Di 3. Tri 4. Tetra 5. Penta 6. Hexa 7. Hepta 8. Octa 9. Nona 10. Deca-

Diatomics There are seven elements that always exist as diatomics Always exist bonded to themselves in nature Example: H H 2 Br. ONCl. IF or Br. INCl. HOF

Practice – Name or give the Formula 1. NF 3 1. Carbon disulfide 2. P 2 O 5 2. Selenium 3. F 2 3. Nitrogen trihydride 4. OBr 2 4. Sulfur dioxide 5. BF 3 5. Phosphorous pentabromide 6. CH 4 6. Xenon hexafluoride 7. NO 7. Tetraarsenic decoxide 8. BN 8. Trinitrogen nonoxide

Answers 1. Nitrogen trifluoride 1. CS 2 2. Diphosphorus pentoxide 2. Se 3. Fluorine 3. NH 3 (ammonia) 4. Oxygen dibromide 4. SO 2 5. Boron trifluoride 5. PBr 5 6. Carbon tetrahydride 6. Xe. F 6 7. Nitrogen monoxide 7. As 4 O 10 8. Boron mononitride 8. N 3 O 9

Naming Binary Acids Contains Hydrogen and one other element The first word has the prefix hydro- , the rest of the first word consists of the root of the second element plus the suffix –ic The second word is always acid Example HCl : hydrochloric acid H 2 S : hydrosulfuric acid

Practice HBr Hydrobromic HI Hydroiodic H 3 P Hydrophosphoric Hydrofluoric acid HF Hydroselenic acid H 2 Se Hydrochloric acid HCl acid

Naming Oxyacid's Contains both a hydrogen and an oxyanion (polyatomic) Keep the root of the oxyanion Include prefixes per- and hypo- as part of the name If the oxyanion ends in –ate replace with –ic If the oxyanion ends in –ite replace with –ous The second word is acid Example HNO 3 : nitric acid HCl. O : hypochlorous acid

Practice H 2 SO 4 Sulfuric HCl. O 4 Perchloric H 3 PO 4 Phosphoric Carbonic Acetic nitrous acid H 2 CO 3 HC 2 H 3 O 2 HNO 2 acid

What is the formula for hydroxic acid? H 2 O HOH

Formation of Covalent Bonds

Look at Fluorine has 7 valence electrons, it needs 1 more electron to form an octet As two fluorine atoms approach one another attractive forces and repulsive forces act upon the two atoms Once that atoms are close enough together they bond covalently to form a fluorine molecule.

Structures Electron Dot Structure Lewis Structure

Practice – Lewis Structures 1. PH 3 2. H 2 S 3. CCl 4

Answers 1. or 2. or 3. or

Single Covalent Bonds They are also called sigma bonds (σ) Sigma bonds occur when the shared pair of electrons is centered between the two atoms

Multiple Covalent Bonds Atoms can share more than one pair of electrons with another atom Double or Triple bonds Oxygen and Nitrogen Multiple covalent bonds consist of one sigma and at least one pi bond (π) Pi bonds form when parallel orbitals overlap and share electrons

How many Sigma and Pi bonds are there? C 2 H 4 C 2 H 2

More Lewis Structures 1. NF 3 2. CO 2 3. Si. F 4 4. CH 4 5. OCl 2 6. NCl 3