Materials Science Atoms and Bonds

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1 Mateial Science Atom an Bon D.-Ing. Nobet Hot Magneium Innovation Cente (MagIC) GKSS Fochungzentum Geethacht GmbH Atom Diamon cytal C Diamon lattice Gahite Gahite lattice Page Atom The atomic tuctue influence the macocoic oetie of a mateial. It can be itinguihe betweent: Maximum Dioe Gla (amohou) Maximum Oe Cytal Page 3

2 Atom Atomic tuctue Atomic coe (otone, neuton, nucleon) Electon on iffeent obit Electon clou (metallic conucitivity) Electon have icete enegy tate ten to occuy lowet available enegy tate on ue obit (valence electon) etemine the atomic bon an ae eonible fo: Chemical eaction Mechanical tength Electical conuctivity Otical aeaance Page 4 Atomic Stuctue Atom: electon 9. x 0-3 kg oton }.67 x 0 neuton -7 kg atomic numbe = # of oton in nucleu of atom = # of electon of neutal ecie A [=] atomic ma unit = amu = / ma of C Atomic wt = wt of 6.03 x 0 3 molecule o atom amu/atom = g/mol C.0 H.008 etc. Page 5 Electonic Stuctue Electon have wavelike an aticulate oetie. Thi mean that electon ae in obital efine by a obability. Each obital at icete enegy level etemine by quantum numbe. Quantum # Deignation n = incial (enegy level-hell) K, L, M, N, O (,, 3, etc.) l = ubiiay (obital),,, f (0,,, 3,, n-) m l = magnetic, 3, 5, 7 (-l to +l) m = in ½, -½ Page 6

3 Atomic Moel Boh atomic moel Wave mechanical moel Page 7 Atomic Moel Comaion of a) Boh an b) wave-mechanical atom moel in tem of electon itibution a) Ditance fom Nucleu Poability b) Page 8 Quantum Numbe Pincial Quantum Numbe 3 4 Shell Deignation K L M N Subhell Numbe of State Numbe of Electon Pe Subhell Pe Shell F 7 4 Page 9 3

4 Electon Configuation Valence electon thoe in unfille hell Fille hell moe table Valence electon ae mot available fo boning an ten to contol the chemical oetie examle: C (atomic numbe = 6) valence electon Page 0 Relative Enegie f Enegy f Pincial Quantum Numbe Page Electonic Configuation ex: Fe - atomic # = N-hell n = 4 valence electon Enegy 3 M-hell n = 3 3 L-hell n = K-hell n = Page 4

5 SURVEY OF ELEMENTS Mot element: Electon configuation not table. Element Atomic # Electon configuation Hyogen Helium (table) Lithium 3 Beyllium 4 Boon 5 Cabon Neon 0 6 (table) Soium 6 3 Magneium 6 3 Aluminum Agon (table) Kyton (table) Why? Valence (oute) hell uually not fille comletely. Page 3 Peioic Table of Element Ia H Li K Na IIA Be IIIB IVB Mg Ca Sc Ti metallic intemeiate nonmetallic } O IIIA IVA VA VIA VIIA He B C N O F Ne VB VIB VIIB VIII IB IIB Al Si P S Cl A V C Mn Fe Co Ni Cu Zn Ga Ge A Se B K Rb S Y Z Nb Mo Tc Ru Rh P Ag C In Sn Sb Te I Xe C Ba RE Hf Ta W Re O I Pt Au Hg Tl Pb Bi Po At Rn F Ra AC Rf Db Sg Bh H Mt D Rae eath eie La Ce P N Pm Sm Eu G Tb Dy Ho E Tm Yb Lu Actinie eie Ac Th Pa U N Pu Am Cm Bk Cf E Fm M No L Page 4 The Peioic Table give u e give u e H Li Be Na Mg C Ba F Ra give u 3e K Ca Sc Rb S Y Column: Simila Valence Stuctue accet e accet e inet gae He O F Ne S Cl A Se Te B I K Xe Po At Rn Electooitive element: Reaily give u electon to become + ion. Electonegative element: Reaily acquie electon to become - ion. Page 5 5

6 Electonegativity Range fom 0.7 to 4.0, Lage value: tenency to acquie electon. Smalle electonegativity Lage electonegativity Page 6 Atomic Bon The foce that hol atom togethe act like ing. 0 = equilibium itance The entie enegy of inteaction E total between two ingle atom conit of attacting E A an eulive E R, enegy E total = E A + E R which have iffeent elation to the atomic acing. Page 7 Atomic Bon E a A = n B E = m A, B, n, m ae mateial an temeatue eenent contant. Page 8 6

7 Ionic Bon Exchange of valence electon to achieve the next cloet inet ga configuation. Cl- Na+ Cl- Na+ Cl- Na+ Na+ Cl- Na+ A E A = Cl- Na+ Cl Cl- Na+ Cl- Na+ Cl- Na+ Na+ = Ne Cl- = A A EA = B E R= n Na+ Cl- Cl- Na+ Cl- Na+ Coulomb boning foce Page 9 Ionic Bon Metal Nonmetal onate electon accet electon Diimila electonegativitie ex: MgO Mg 6 3 O 4 [Ne] 3 Mg + 6 O - 6 [Ne] [Ne] Page 0 Ionic Boning Occu between + an - ion. Requie electon tanfe. Lage iffeence in electonegativity equie. Examle: NaCl Na (metal) untable Na (cation) table electon + - Coulombic Attaction Cl (nonmetal) untable Cl (anion) table Page 7

8 Ionic Boning Enegy minimum enegy mot table Enegy balance of attactive an eulive tem E N = E A + E R = A B n Reulive enegy E R Inteatomic eaation Net enegy E N Attactive enegy E A Page Examle: Ionic Boning Peominant boning in Ceamic NaCl MgO CaF CCl Give u electon Acquie electon Page 3 Covalent Boning imila electonegativity hae electon bon etemine by valence & obital ominate boning Examle: CH 4 C: ha 4 valence e -, nee 4 moe H: ha valence e -, nee moe Electonegativitie ae comaable. CH 4 hae electon fom cabon atom hae electon fom hyogen atom Page 4 8

9 Metallic Bon ea of valence electon ionic coe Page 5 Pimay Boning Metallic Bon -- elocalize a electon clou Ionic-Covalent Mixe Boning % ionic chaacte = e (X A X B ) 4 x (00%) whee X A & X B ae Pauling electonegativitie Ex: MgO X Mg =.3 X O = 3.5 (3.5.3) % ionic chaacte = e 4 x (00%) = 70.% ionic Page 6 Summay: Pimay Bon Ceamic (Ionic & covalent boning): Metal (Metallic boning): Polyme (Covalent & Seconay): econay boning Lage bon enegy lage T m lage E mall α Vaiable bon enegy moeate T m moeate E moeate α Diectional Poetie Seconay boning ominate mall T m mall E lage α Page 7 9

10 SECONDARY BONDING Aie fom inteaction between iole Fluctuating iole aymmetic electon ex: liqui H clou H H econay Pemanent iole-molecule inuce -geneal cae: -ex: liqui HCl boning H H Aate fom Fig..3, Callite 7e. econay boning econay H Cl H Cl boning H H econay boning -ex: olyme econay boning econay boning Page 8 Seconay Bon Page 9 Summay: Boning Tye Ionic Covalent Metallic Seconay Bon Enegy Lage! Vaiable lage-diamon mall-bimuth Vaiable lage-tungten mall-mecuy mallet Comment Noniectional (ceamic) Diectional (emiconucto, ceamic olyme chain) Noniectional (metal) Diectional inte-chain (olyme) inte-molecula Page 30 0

11 Poetie Fom Boning: T m Bon length, Melting Temeatue, T m Enegy Bon enegy, E o Enegy o malle T m untetche length o E o = bon enegy lage T m T m i lage if E o i lage. Page 3 Poetie Fom Boning : α Coefficient of themal exanion (CTE), α length, Lo coeff. themal exanion unheate, T ΔL heate, T ΔL Lo = α (T -T ) α ~ ymmety at o Enegy untetche length o malle α E o E o lage α α i lage if E o i malle. Page 3 Atomic Bon covalent Semi conucto metalic Polyme V. e Waal Metal Ceamic & Gla ionic Page 33