ATOMIC THEORY Chemistry founded on 4 assumptions 1)All matter composed of atoms 2)Atoms that make-up elements are diff diff. elements ----  atom make-up diff 3)Cmpds. are composed of elements in fixed ratio BaCl 2 1 atom Ba 2 atoms Cl C 2 H 3 O 2 2 atoms C 3 atoms H 2 atoms O 4)Chemical rxns only involve change in atom ratios to produce new subst., not change in atoms themselves Atomic Weight: Ave. mass of elements based on % abundance

ATOMS – neutral change Comprised of: Nucleus: + charge protons, p + 0 charge neutrons, n 0 - Charge electrons, e - # p+ atomic #, “Z” p + = e - no charge to atom Protons identify elements P. table, elements listed in atomic number Mass # atomic weight rounded to nearest whole # p + + n o = mass #, “A”

ATOM ---charged Termed: ION Cation: + charged Anion: - charged # p + > # e - “+” charge # p + < # e - “-” charge ISOTOPE & NOTATION Diff. make-up of same element 1)Not change element itself, same # p + 2)Diff. # of n 0 3)Change atomic weight/mass FORMS: Potassium - 39 K - 39 result is change in Density same element, same # p +, only change # e -

Element or Compound ???? Element: represented on the p. table; cannot be broken down Compound: joining together of 2+ elements, or two of the same element together; can be broken down into simpler subst. Ionic or Covalent ???? Ionic: metal + nonmetal joined together to form an ionic cmpd. by forming an ionic bond Covalent: nonmetal + nonmetal joined together to form a covalent molecule by forming a covalent bond

PERIODIC TABLE - arranged atomic # - 7 rows; periods/series - 18 columns; groups/families elements in each group – similar chemical properties Groups numbered in 2 ways Group A/B Group Group A/B Main Group “A” : first 2 col. left, last 6 col. rgt. Transistion Metals “B”: 10 col. in middlde Group 1 – 18 Each col. numbered 1 thru 18, left to right Inner Transition Metals (Rare Earth) Lanthanide Series; elements Actinide Series; elements 90 – 103 not 14 col., not numbered just the facts mamme

1A : ALKALI METALS elements 1 st col.: Li, Na, K, Rb, Cs, Fr Shiny, soft, low melting pt. React violently w/ H 2 O produce alkaline (or basic) Not found in pure state, combined w/ other elements in cmpd. 2A: ALKALINE METALS elements 2 nd col.: Be, Mg, Ca, Sr, Ba, Ra shiny, silvery less reactive than 1A Not found in pure state

7A: HALOGENS (HALIDES) elements next to last col.: F, Cl, Br, I, At colored, corrosive nonmentals found combined w/ elements Halogen (HALS) - salt 8A: NOBLE GASES (INERT) elements last col.: He, Ne, Ar, Kr, Xe, Rn colorless gases, nonmetals low reactivity w/ other subst. INERT - nonreactive

e- structure e- locate: outside of nucleus e- cloud, shell, “subshell”, orbital, E-level E is quantized; a specific value Shell ( E Level) 1 st : closest to nucleus, lowest in E 7 th : farthest from nucleus, highest in E w/i shells are “subshells” s, p, d, f w/i subshells are orbitials geometric shaped regions where the high probability to locate e - exists

charge mass location determine p + “+” 1 nucleus element n 0 “0” 1 nucleus isotope e - “-” 0 outside chemistry

p+n0p+n0 1 st shell 2 nd shell 7 th shell

Shell subshell orbitial max. e s s, p s, p, d s, p, s, p, s, p, d s, p d, f d, f s: 1 st 2 elements of each row; 1 pair, 2 e-; 1A - 2A p: last 6 elements of each row; 3 pair, 6 e-; 3A - 8A d: transition elements; 5 pair, 10 e-; B f: rare earth elements; 7 pair, 14 e-; not labeled

How many e- are present, group by E-levels He Be N F Na Al 1st ---> 2e- 1st ---> 2e- 2nd ---> 2e- 1st ---> 2e- 2nd ---> 5 e- 1st ---> 2e- 2nd ---> 7 e- 1st ---> 2e- 2nd ---> 8 e- 3rd ---> 1 e- 1st ---> 2e- 2nd ---> 8 e- 3rd ---> 3 e-

Now, identify e- by subshells He Be N F Na Al 1st :2e- 1st:2e- 2nd:2e- 1st:2e- 2nd:5 e- 1st:2e- 2nd:7 e- 1st:2e- 2nd:8 e- 3rd:1 e- 1st:2e- 2nd:8 e- 3rd:3 e- s s s s, p s s, p s s s, p s, p

E- Notation Form: 1s 2 E-level “shell” subshell # e- Be N F Na Al 1s 2 2s 2 1s 2 2s 2 p 3 1s 2 2s 2 p 5 1s 2 2s 2 p 6 3s 1 1s 2 2s 2 p 6 3s 2 p 1 1s 2 2s 2 2p 3 1s 2 2s 2 2p 5 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 3s 2 3p 1 Ca 1s 2 2s 2 p 6 3s 2 p 6 4s 2

After 4s 2, 3d level fills till 3d 10 completed, then complete 4p 4p to 5s, 4d completed, then complete 5p 5p to 6s, 4f level fills till 4f 14 completed, then start 5d to 6p Mn 1s 2 2s 2 p 6 3s 2 p 6 4s 2 3d 5 Zn 1s 2 2s 2 p 6 3s 2 p 6 4s 2 3d 10 Ga 1s 2 2s 2 p 6 3s 2 p 6 4s 2 3d 10 4p 1 Pd-46 1s 2 2s 2 p 6 3s 2 p 6 4s 2 3d 10 4p 6 5s 2 4d 8 Nd 1s 2 2s 2 p 6 3s 2 p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 5d 1 4f 3

Group E-levels Order e- Filling Short-cut 1s 2 2s 2 p 6 3s 2 p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 5d 1 4f 3 1s 2 2s 2 p 6 3s 2 p 6 d 10 4s 2 p 6 d 10 f 3 5s 2 p 6 d 1 6s 2 1s 2 2s 2 p 6 3s 2 p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 5d 1 4f 3 describes noble end of row 5 (Xe) this is added on to the noble gas notation filled inner core of e- [Xe]4f 3 5d 1 6s 2 Valance e- (2) total # of e- in highest E-level methods easiest to show # val. e-

CONVERSIONS 1 amu = * grams What is the mass, in grams, of 100,000 atoms of Au with an amu of 197? Setup * g Au CONSTANT 1 amu = * g

Remember, keep in mind that 1. Natural tendency is toward min. E; ground state lowest E arrangement of e- 2. Each orbitial can only hold a max. 2 e- Hund’ Rule & Pauli Exclusion Principal

RELATIVE ATOMIC WEIGHT NEON Isotopes 20 Ne 21 Ne 22 Ne Isotope Mass % Abundance % 0.27 % 9.25 %

20 Ne 21 Ne 22 Ne * * * = = =

PAULI EXCLUSION PRINCIPLE An orbital can hold only 2 e - ’s & the 2 e - ’s must have opposite spin Spin is described as either clockwise or counter-clockwise An orbital occupied by 2 e - ’s w/ opposite spin is filled 2 Hydrogen atoms 1s 1 & 1s 1 H -- H 2 e - ’s w/ same spin direction cannot occupy same region of space W i l l these 2 hydrogen atoms bond together ? ? ? ? ? Only if the 1s e - ’s are of opposite spin

RULES RULES & PRINCIPLES HUND’S RULE Describes the lowest E arrangement of e - 1. e - enter orbital of same E singularly till orbital half filled 2.Each orbital must be occupied with an e - w/ parallel spin direction before e - ’s are paired w/ opposite spin Based on results of measurements of magnetic properties

E-Level Diagrams Energy Increase SHELL SUB SHELL 1 s 2 s p 3 s p d 4 s p d 5 s p 4f 5d

FILLING ORBITALS S1s 2 2s 2 p 6 3s 2 p 4 1 s 2 s pXpX pYpY pZpZ 3 s pXpX pYpY pZpZ 1s 2sp 3sp Valence e - level 6 valence e - ’s

FILLING ORBITALS Co1s 2 2s 2 p 6 3s 2 p 6 d 7 4s 2 1 s 2 s pXpX pYpY pZpZ 3 s pXpX pYpY pZpZ 1s 2sp 3sp s 4s 2 d 7 d d d d d 6 2 Valence e - ;s

FILLING ORBITALS Cr1s 2 2s 2 p 6 3s 2 p 6 d 5 4s 1 1 s 2 s pXpX pYpY pZpZ 3 s pXpX pYpY pZpZ 1s 2sp 3sp s 4s 1 d d d d d d 1 valence electron 5

RULES RULES & PRINCIPLES HUND’S RULE Describes the lowest E arrangement of e - 1. e - enter orbital of same E singularly till orbital half filled 2.Each orbital must be occupied with an e - w/ parallel spin direction before e - ’s are paired w/ opposite spin Based on results of measurements of magnetic properties DIAMAGNETIC: Atoms w/ e - ’s paired PARAMAGNETIC: Atoms w/ unpaired (odd) e - ’s

What Element??? Atom?? 1 s 2 s pXpX pYpY pZpZ 3 s 1s 2 2s 2 p 6 3s 2 p 6 s 4 3 d d d d d pXpX pYpY pZpZ s 4 3 Ni Nickel

Diagram for Se (Selenium) 1 s 2 s pXpX pYpY pZpZ 3 s pXpX pYpY pZpZ s 4 1s 2 2s 2 p 6 3s 2 p 6 s 4 3 d d d d d 4 p p p pXpX pYpY pZpZ 4 3 d d d d d