Chapter 9 Notes Mr Nelson 2009

Practice PCl5 dihydrogen monoxide SF6 carbon trichloride N2O disulfur hexoxide NO2 nitrogen triiodide

Naming Acids An acid is any compound that starts with a hydrogen When naming an acid: 1st locate the anion (- charge)

Acid Nomenclature If the anion in the acid ends in –ide (not PI) change the ending to -ic acid and add the prefix hydro- hydro________ic acid HCl: hydrochloric acid

Acid Nomenclature If the anion in the acid ends in –ite (all PI’s) change the ending to -ous acid. _________ous acid HClO2: chlorous acid

Acid Nomenclature If the anion in the acid ends in –ate (all Pi’s) change the ending to -ic acid. ___________ic acid HClO3: chloric acid I

Acids – Finishing Up If you have the name and need to find the formula Example: Acetic Acid Cross off the –ic and add at –ate Acetate! = C2H3O2- Finish by adding the correct # of H’s (1 for every negative) HC2H3O2 is acetic acid 

Covalent Bonding Covalent bond – atoms share electrons. There are several electrostatic interactions in these bonds: Attractions between electrons and nuclei Repulsions between electrons Repulsions between nuclei

Lewis Dot Structures ONLY Valence (outer) electrons are involved. Lewis dot structures can be drawn for: atoms molecules Lewis dot structures show structure of a molecule, and help predict shape.

Steps to Writing Lewis Structures Find the sum of valence electrons of all atoms in the polyatomic ion or molecule. PCl3 5 + 3(7) = 26

Writing Lewis Structures Arrange element symbols to show how atoms are connected – show electrons as dots. Follow the octet rule except for hydrogen, which only needs two electrons to be full Connect the electrons as lines Keep track of the electrons: 26 - 6 = 20

Writing Lewis Structures Fill the octets of the outer atoms. Keep track of the electrons: 26 - 6 = 20; 20 - 18 = 2

Writing Lewis Structures Fill the octet of the central atom. Finish by checking for octets. Keep track of the electrons: 26 - 6 = 20; 20 - 18 = 2; 2 - 2 = 0

Writing Lewis Structures If you run out of electrons before the central atom has an octet… …form multiple bonds until it does.

Exceptions! Boron and Aluminum are okay with only 6 e- around them BF3

Exceptions If the Lewis Dot Structure you are drawing is an ion: Use [] and specify the charge Add or subtract electrons Positive charges take away electrons Negative charges add electrons Example: Br-