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CH. 23 TRANSITION ELEMENTS

CH. 23 TRANSITION ELEMENTS. RECALL 1. characteristics of alkai & alkaline metals 2. Hund’s Rule 3. e - notation; elements / ions 4. why transition element? 5. Lewis acid-base 6. Magnetism. 1. Alkali : shiny, soft, low melting / boiling pt,

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CH. 23 TRANSITION ELEMENTS

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  1. CH. 23TRANSITION ELEMENTS RECALL 1. characteristics of alkai & alkaline metals 2. Hund’s Rule 3. e- notation; elements/ions 4. why transition element? 5. Lewis acid-base 6. Magnetism 1. Alkali: shiny, soft, low melting/boiling pt, react w/ H2O, not found natural state, low IE, ns1, strong red agents, very soluble salts Alkaline: shiny, silvery, higher melt/boil pts, not found natural state, less react than 1A, ns2,higher IE, strong red agents, lower solubility 2. e- enters orbital 1 at a time till orbital half filled w/ same spin, then pair w/ opposite spin 4. occupied “d” orbital e- in neutral state 5. donate-accept e- pair 6. dia & para magnetic

  2. Fe, Co, Ni, Cu, Ag some most familiar & imprt trans elements Jet Engine 38% Ti 6 % Co 0.022 Ta 37% Ni 5% Al 12% Cr 1% No Numerous chem properties, consider: general aspects ox #’s

  3. OXIDATION STATES 1. loss outer s e- first 2. loss additional d e- Existence of d e- contribute to characteristics 1. more than 1 stable ox state 2. colored cmpds 3. magnetic properties Common ox state in soln not same ox state in solid Mn+2(aq) MnO4-(aq) MnO2(s) Organometallic Cmpds: metal in low + state or - state Exotic Cmpds: in ox state not shown

  4. Ex. MnO4-2 is stable in strong basic soln. In acidic soln, reacts to form permanganate and MnO2(s). Wrtie balanced overall rxn from the two half-rxns.

  5. IONS IN AQUEOUS SOLUTION 1st Series 1. Except Cu neg std electrode potential (red) for +2 state 2. Act as Lewis acid to H2O molecules form metal complex w/ other ion/molecules present Co(H2O)6+3(aq) Eo = 1.95 V Co(NH3)6 +3(aq) Eo = 0.10 V more stable as Co +3(aq) 3. L to R, red potential increase L to R lower ox state, incr eff nuclear charge 4. Same trend for 2nd & 3rd series ReO4-2 (MnO4-) Cd+2 (Zn+2) crude comparisons, many diff chem properties

  6. Ex. Write balance eqn of CuS in 3M HNO3. Cu(s) + H+(aq) + NO3-1(aq) -----> Cu+2(aq) + S(s) + NO(g) + H2O(l)

  7. TREND OF OXIDES 1. For specific element, highest ox state act as ox agent Sc2O3 & TiO2 not good CrO3 & Mn2O7 good 2. Low states, basic high state, acidic in soln in H2O FeO (insol in H2O or base), disolve in acidic soln, thus, exhibits basic characteristics 3. Shift ionic to covalent behavior in Met-O bond as metal ox # increases, attraction for e- on “O” incr MnO ionic Mn2O7 polar covalent

  8. OXIDES -- PAINT PIGMENTS NOT chem  when exposed to sunlight/air *color due from incomplete filled d-shell *depend on particular metal & ox state Co: orange - purple - green - violet Ni: blue - greenish

  9. MAGNESTISM Para: unpaired e- in valence shell, d orbital drawn into magnetic field Dia: pair e-, repelled by magnetic field nd0 or nd10 DIA PARA FERRO no centers isolated centers coupled centers aligned Ferromagnetism: overlap of atomic orbitals most common: Fe, Co, Ni permanent magnets

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