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Basic structure
John Daltons-Atomic theory JJ Thomson/Crookes-Cathode Ray
Tube Experiments & Plum pudding model
Rutherford-Gold Foil Experiment Millikin’s Oil Drop Experiment
Protons mass = 1 amu charge +1
Neutrons mass = 1 amucharge 0
Electrons mass = negligible charge -1
Amu = atomic mass unit. 1 amu = _____________ grams
Txt pg
Protons mass = 1. 0073 amu charge = +1.69 x 10- 19
Coulumbs (+1 Charge)
Nuetronsmass = 1.0087 amu charge = 0
Coulumbs
Electronsmass = 0.0005486 amu charge = -1.69 x 10- 19 Coulumbs
(-1 Charge)1.0073 amu1.0087 amu0.00005486 amu
Atomic mass vs Atomic Weight
Atomic mass = mass of an individual atom
Atomic Weight = average mass of all the isotopes (Carbons atomic wt. = 12.011)Carbon -12 12C Carbon -14 14C
6 protons 6 protons 6 neutrons 8 neutrons 6 electrons 6 electrons
Isotopes
Same element, different mass (due to differing amts. of neutrons)
Stable elements #Protons (p) = #Neutrons(n)
Radioisotopes are the unstable form of the element due to having a larger number of neutrons than protons
Isotope symbols
Uranium -236 236 UWe can always assume that a atom is
neutral unless notedAtomic number tells us the protons (92).
This is many times left off the symbol because it will always be 92 if the element is U.
We assume then that there must be 92 e-The mass number tells us the # neutrons.
Average atomic weight
Takes the most stable isotopes and their relative abundance to calculate the averages
Ions
Atoms whose electrons do not equal the protons.Metals = cations (+ ions)
Nonmetals = anions ( - ions)Opposites attract to form ionic cpds
(very strong bond=almost always solids with high melting pts)
Fe +3 and Cl -1
Predicting formulas
Review: The atoms always combine so that the number of + balances the number of – charges. Criss Cross method
Polyatomic ions
Groups of atoms with a charge Treat as a single unit. Place ( ) around it if you have more
than l
Ca + 2 and NO3 -1
Naming Ionic
First name is the name of the element written first (cation) unless it’s the Group NH4+1 (ammonium)
Last name is the name of the element written last with an ide ending unless it’s a group (then use the group name) NaCl NaNO3 CaBr Ca(IO3) Ag2S Ag CN
Middle names
Ionic cpds that have a metal with more than one charge/oxidation state need middle names (mainly transitional elements) Fe+2 and Fe +3 Cu +1 and Cu +2 Pb +2 and Pb +4 Sn +2 and Sn +4 Hg +1 (Hg2+2) and Hg +2
Molecular cpds
These are primarily nonmetals elements attached to nonmetal elements due to the sharing of their valence electrons (Also called covalent cpds)
Which of the following are ionic (metal/non) and which are molecular (non/nonmetal) CaBr2 AgF SO2
LiNO3 IF5 CCl4 Cl2 BI3
Naming molecular cpds
First name is the name of the element written first
Last name is the name of the element written last with an ide ending Sulfur= sulfide chlorine = chloride Oxygen = oxide iodine = iodide
Both names have a prefix indicating the number of each atom