Chem

Chapter 4 History and Atomic Structure

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[object Object],[object Object],[object Object],[object Object],[object Object]

Obj. 1…Dalton’s Atomic Theory ,[object Object],* * 2. Atoms of the same element are identical... each element is unique proton, neutron and electron isotopes exist ,[object Object],with 2 exceptions 3. Atoms of different elements can physically mix or chemically combine (compounds). 1. All elements are composed of tiny, indivisible particles called ‘atoms’. 4. Chemical rxns. occur when atoms are separated, joined, or rearranged.

Obj. 2…Atomic Scientists ,[object Object],[object Object],tube filled with gas. ,[object Object],traveled from the cathode (-) to the anode (+).

Obj. 2 cont... ,[object Object],in 1886. ,[object Object],cathode rays. ,[object Object],Rutherford in 1920. ,[object Object],different atoms’ atomic mass and atomic # (# of protons) were not adding up. ,[object Object],in 1932.

Obj. 2 cont... ,[object Object],[object Object],[object Object],the electron more in depth.

Obj. 3 and 4…The Bohr-Rutherford Model 1. atoms are mostly space. (football arena) ,[object Object],experiment’ (1911) which concluded that: 2. atoms have a solid nucleus at the center which contains most of the mass. ,[object Object],time.

Obj. 3 and 4 cont... ,[object Object],[object Object],[object Object],[object Object],[object Object],(BBs and cream cheese!)

Obj. 3 and 4 cont... ,[object Object],[object Object],Plum Pudding Rutherford Rutherford-Bohr Quantum ,[object Object],the atom by concentrating on the e- (1913). ,[object Object],orbits around the nucleus. ,[object Object],lose energy.

Obj. 5…Subatomic Particles PROPERTIES OF SUBATOMIC PARTICLES e- p + n 0 -1 +1 0 1/1840 1 1 9.11 x 10 -28 1.67 x 10 -24 1.67 x 10 -24 PARTICLE SYMBOL ELECTRICAL CHARGE RELATIVE MASS ACTUAL MASS (g) Electron Proton Neutron

Obj. 6…Characteristics of Elements atomic # element symbol element name atomic mass K 19 Potassium 39.098

Obj. 6 cont... ,[object Object],[object Object],[object Object],[object Object],(change atomic # = change of element). ** (+) charge = less e- than p + ** (-) charge = more e- than p + ,[object Object],[object Object],[object Object],[object Object],(a.k.a. mass #)

Obj. 7…Atomic Symbols ,[object Object],[object Object],OR ,[object Object],name of element followed by atomic mass. ,[object Object],Carbon - 14 Aluminum - 27 Nitrogen - 14 # X # atomic mass (# of p + ) atomic # element symbol # X atomic mass element symbol ,[object Object],either notation!

Obj. 8…Atomic Calculations ,[object Object],- only p + and n 0 are in the nucleus. - if you know the mass of any atom, you can find the # of n 0 . ,[object Object],element = _______________ atomic mass = ___________ atomic # = ______________ # of p + = _______________ # of n 0 = _______________ # of e - = _______________ Phosphorus 31 a.m.u.s 15 15 16 14 Manganese - 55 symbol = ______________ atomic mass = __________ atomic # = ____________ # of p + = ______________ # of n 0 = ______________ # of e - = ______________ Mn 55 a.m.u.s 25 25 30 25 31 P 15 +1 electrical charge on atom - if you know the # of n 0 and the # of p+, you can find the mass.

Obj. 9…Isotopes - different # of n 0 !!! ,[object Object],Carbon - 14 Carbon - 12 Carbon - 13 (6p + , 6n 0 ) (6p + , 7n 0 ) (6p + , 8n 0 ) ,[object Object],element of life extremely rare radioactive…carbon dating ,[object Object],only mass and # of n 0 do! 22 X 12 +3 22 X 10 25 X 10 -1 Neon - 20 Neon - 22 Fluorine - 20 ,[object Object],masses .

Obj. 10…Average Mass of Isotopes ,[object Object],- abundance of isotope is just as important as mass! ,[object Object],Natural copper (Cu) consists of 2 isotopes ... Copper - 63 (mass = 62 .930 g/mole) Copper - 65 (mass = 64 .930 g/mole) 69% 31% ,[object Object],mass x abundance for each isotope Step 1 : Step 2 : add the two values from step 1 together 62 .93 x .69 = 64 .93 x .31 = 43.42 20.13 43.42 20.13 + ,[object Object],avg. of all isotopes that exist in nature. 63.55 g/mole

Obj. 10 cont... ,[object Object],Three isotopes of Oxygen: Oxygen - 18 Oxygen - 16 Oxygen - 17 99 . 759% 0.037% 0.204% ,[object Object],Oxygen-16 is the isotope that is most abundant in nature. ,[object Object],that is most plentiful in nature.

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