1. Chapter 6

2.  Vocabulary page 226  Section 6.1 Reading, 10 questions and their answers, pages 194-201

3.  Covalent Bond – a bond that occurs when 2 atoms share valence electrons.  Covalent bonds usually occur between nonmetal atoms.  How they form: 1. As 2 atoms approach each other, the attractions are initially stronger than the repulsions. 2. The covalent bond forms when the energy is minimized; or when attractions = repulsions.

5.  video video

6.  Bond Length – average distance between 2 atoms covalently bonded.  Bond Energy – energy needed to break a covalent bond.  High bond energy = short bond length

7. 1. Nonpolar Covalent Bond – bond in which electrons are shared equally. 2. Polar Covalent Bond – bond in which electrons are shared unevenly because they are pulled toward the more electronegative atom.  This creates a dipole – the bond has a partially positive and negative end.  Electronegativity – ability of an atom to attract electrons to itself.  Polar Covalent Bonding Polar Covalent Bonding

8.  If the electronegativity difference between atoms is:  from 0 – 0.4NONPOLAR  from 0.5 – 2.0POLAR  Greater than 2.0IONIC

10.  Lewis Dot Symbol (Electron Dot Symbol) – uses dots to depict the number of valence electrons an atom has.  Valence Electrons – electrons in the highest occupied energy level of an atom that participate in chemical bonding.

12.  calcium  iodine  1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 2  neon  aluminum

13.  Molecular Compound – compound in which atoms, not ions, are covalently bonded by sharing electrons to form molecules.  Ionic Compounds are named with the Stock system  Molecular Compounds are named with the prefix system.  Ionic compounds typically contain metals and nonmetals.  Molecular compounds typically contain only nonmetals.

14. 1. Use the full name of the 1 st element. Only add a prefix if there is more than 1 atom.  1 = mono-2 = di-3 = tri- 4 = tetra-  5 = penta-6 = hexa-7 = hepta-  8 = octa-9 = nona-10 = deca- 2. Change the name of the 2 nd element to end in –ide. Always add a prefix to indicate the number of atoms. 3. Drop the ‘o’ or ‘a’ from a prefix if an element name begins with a vowel.

15.  carbon dioxide  dinitrogen pentoxide  sulfur hexafluoride  dihydrogen monoxide

16.  CCl 4 N2O3N2O3  PF 5  Cl 2 O

17.  AlBr 3  AsBr 3  Cu 2 S  P 2 O 3

18.  Lewis Structure – diagram that shows the structure of a covalently bonded molecule using only valence electrons. It includes lone pairs and bond pairs of atoms bonded together.  Lone Pair – unshared pair of electrons not involved in a covalent bond.  Bond Pair – pair of electrons shared by 2 atoms to form a covalent bond.  Lone pairs are represented with dots; bond pairs with dashes (-).

19.  Single Bond – bond in which one pair of electrons is shared between atoms.  Double Bond – bond in which 2 pairs of electrons are shared.  Triple Bond – bond in which 3 pairs of electrons are shared.  Triple bonds tend to have the highest bond energy and shortest bond length.

20. 1. Determine the total number of valence electrons from all atoms in the molecule. 2. Choose a central atom and arrange all atoms to show how they are bonded.  C is ALWAYS a central atom. Otherwise, the first atom in the formula is probably the central atom. 3. Fill in lone pairs until all atoms have an octet. H should have just 2 valence electrons (exception to octet rule!).

21. 4. Check to make sure the total number of electrons is correct. If not, change the bond types.

22. 1. CCl 2 F 2 2. HOCl 3. CS 2 4. SO 2 5. NF 3

23.  Anions – ADD electrons to the total due to the negative charge.  Cations – must SUBTRACT electrons from the total due to the positive charge.

24.  Resonance Structures – equivalent Lewis structures that can be drawn to represent the same molecule or ion.

25. 1. Less than an Octet  Hydrogen will have 2 valence electrons  Boron is stable having 6 valence electrons 2. Odd Number of Valence Electrons  Causes the molecule or ion to be very unstable and reactive  The more electronegative atom(s) will have octets. 3. Expanded Octet – elements in the 3 rd period of the PT and below can be stable having more than 8 valence electrons as central atoms.

26.  Names / formulas of molecular compounds (prefix system)  Lewis Dot Symbols and valence electrons  Drawing Lewis Structures

27.  Si - O  Cl – Cl  K – S  Li - F

28.  SeBr 6  S2Cl3  P2O5  dinitrogen monoxide  phosphorus trihydride

29.  Finish Molecular Modeling Lab in groups.  Read section 6.2 and write 10 questions and answers.

30.  VSEPR Theory – Valence Shell Electron Pair Repulsion theory  Electron pairs will orient themselves as far apart as possible to minimize repulsions.  Shapes of molecules are based on how many ATOMS and LONE PAIRS are around the central atom.

38.  A molecule / polyatomic ion is POLAR if: 1. At least one bond is POLAR (electronegativity difference of 0.5 or more. 2. All dipole moment arrows point in the same general direction (left, right, up, down).  Dipole moment – arrow drawn to show the more electronegative atom in a polar bond.  Polarity of Water Polarity of Water

40. 1. Draw Lewis Structures showing the correct shape. 2. Add dipole moment arrows (if there are any). 3. Is the molecule Polar or Nonpolar?

41. 1. Read section 6.4 and write 10 questions and answers. Turn in. 2. Complete Term Review #1-10 page 227 and Test Prep #1-12 page 231. 3. If finished, you should begin the chapter 6 review sheet.