1. Basic Atomic Structure 1/16/09

2. I. Subatomic Particles subatomic particle = a particle found inside the atom nucleus = small, dense area in center of atom (p + & n 0 found here). amu (atomic mass unit) = exactly 1/12 the mass of carbon-12 atom. in a neutral atom, number of p + = number of e - (# of n 0 varies). isotope = a variety of an atom that contains a different number of neutrons compared to others (still has same number of p + ). Name ChargeSymbol LocationMass proton +1p+p+ in the nucleusapprox. 1 amu (1.007 amu) neutron 0n0n0 in the nucleusapprox. 1 amu (1.008 amu) electron e-e- in orbitals around nucleus negligible amu (0.000549 amu)

3. II. Describing the Atom atomic symbol = a capital letter (or 1 capital, 1 lowercase) that symbolizes an element. Usually comes from current name, but can also originate from another language. isotopic notation = way of writing the symbol to include the number of protons and neutrons (in nucleus). 1.C = (just symbol for carbon) 2.carbon-12 = form of carbon with 12 total particles in the nucleus. 3.C-12 = another way to write #2 (using symbol instead of name) 4. 12 C = another way to write #2 (must be in upper-left -hand corner) Modern NameSym.Older Name silverAgargentum goldAuaurum copperCucuprum ironFeferrum mercuryHghydragyrum potassiumKkalium sodiumNanatrium leadPbplumbum antimonySbstibium tinSnstannum tungstenWwolfram

4. III. Atom Numbers atomic number = number of p +. Written in bottom- left -hand corner of symbol. Identifies the element. mass number = number of p + & n 0. Identifies the isotope. Written in top-left -hand corner. atomic mass (or weight ) = weighted average of all the mass numbers of all the isotopes of an element. Not written on symbol, but is found on PT. C 14 6 Carbon 6 C 12.01 Carbon 6 C 12.01 atomic mass is calculated by multiplying the mass number of each isotope by its abundance in the environment (a percentage).

5. Hydrogen 1 H 1.008 Hydrogen 1 H 1.008 atomic mass is calculated by multiplying the mass number of each isotope by its abundance in the environment (a percentage). Ex : hydrogen has three isotopes… 1. protium (1 p +, 0 n 0 ) @ 99.985% 1.0078 amu x 0.99985 = 1.007648830 amu 2. deuterium (1 p+, 1 n 0 ) @ 0.0149% 2.0141 amu x 0.000149 = 0.000300101 amu 3. tritium (1 p +, 2 n 0 ) @ 0.0001% 3.016 amu x 0.000001 = 0.000003016 amu 1.007951947 amu ≈ 1.008 amu

6. atomic mass tells you two very important things about an element: 1. the mass of one atom of an element, measured in amu. hydrogen = 1.008 amu per atom carbon = 12.01 amu per atom gold = 196.97 amu per atom

7. 2. the mass of one mole of an element, measured in grams. hydrogen = 1.008 grams per mole carbon = 12.01 grams per mole gold = 196.97 grams per mole

8. mole = a counting unit (like “dozen” or “gross”), representing 6.022 x 10 23 particles of an element/compound. One mole of ANY element/compound will contain 6.022 x 10 23 p articles. Avogadro’s number = number of atoms found in exactly 12 grams of carbon-12, which is ( surprise!) 6.022 x 10 23. 602,200,000,000,000,000,000,000 Let’s see if you can incorporate what you’ve learned...

9. Fill in the missing information using your periodic table: Name of IsotopeSymbol Atomic Number Mass Number Charge # of Neutrons # of Protons # of Electrons fluorine-___ 010 121110 cobalt-60 +227 oxygen-17 8-2 76 As __ 36