资源描述
Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Fundamental of Materials Science and Engineering,Fundamental of Materials Scien,Introduction,Chapter 1 Atomic Bonding,Chapter 2 Crystal Structures,Chapter 3 Defects,Chapter 4 Glass structure,Chapter 5 Phase diagram,Chapter 6 Processing,Chapter 7 Forming,Chapter 8 Sintering,Chapter 9 Mechanical properties,Chapter 10 Thermal properties,Chapter 11 Electrical properties,Chapter 12 Optical properties,-,2,-,References:,William F.Smith&Javad Hashemi:Foundations of Materials Science and Engineering,William D.Callister,Jr.:Materials Science and Engineering:An introduction(本科生专业外语教材),Introduction Chapter 1 Atomic,Chapter 1:Atomic Bonding,1.1 Atomic structures,electron,Nucleus,Atom consists of a nucleus,(positive charged)and,electrons(negative charged),Electrons are characterized,by four quantum numbers,Principle quantum number:n=1,2,.,K,L,M,N,O,Orbital quantum number:,l,=0,1,n-1,s,p,d,f,Magnetic quantum number:m=,l,.,1,0,-1,-,l,Spin quantum number:s:1/2 and-1/2,-,3,-,Chapter 1:Atomic Bonding1.1 A,n:determines the position of the shell.,l,:determines the shape of orbitals or subshells in each shell.,m:represents the orientation/number of the orbitals within each shell.,s:represents the direction of spin.,l,m,number of orbitals,0,s,0,1,1,p,+1,，,0,，,-1,3,2,d,+2,，,+1,，,0,，,-1,，,-2,5,3,f,+3,，,+2,，,+1,0,-1,-2,-3,7,Pauli exclusion principle:,no electron can have the same,set of four quantum numbers,-,4,-,n:determines the position of,n,l,m,#of orbital,Maximum#,of electrons,1,0,0,1,1s,2,0,1,0,1,0,-1,1,3,2s,2p,3,2,0,1,2,0,1,0,-1,2,1,0,-1,-2,1,3,5,3s,3p,3d,2,6,2,6,10,8,18,Electron#in each shell:2n,2,-,5,-,nlm#of orbitalMaximum#10011,Relative energy level of orbitals,6s,5p,4d,5s,4p,3d,4s,3p,3s,2p,2s,1s,Energy,Each orbital,consists of 2 electrons.,-,6,-,Electrons fill the orbitals with lowest energy first.,Relative energy level of orbit,Examples(electronic structure notation):,H(1):1,s,1,B(5):1,s,2,2,s,2,2,p,1,C(6):1,s,2,2,s,2,2,p,2,N(7):1,s,2,2,s,2,2,p,3,O(8):1,s,2,2,s,2,2,p,4,Na(11):1,s,2,2,s,2,2,p,6,3,s,1,Mg(12):1,s,2,2,s,2,2,p,6,3,s,2,Al(13):1,s,2,2,s,2,2,p,6,3,s,2,3,p,1,Si(14):1,s,2,2,s,2,2,p,6,3,s,2,3,p,2,Cl(17):1,s,2,2,s,2,2,p,6,3,s,2,3,p,5,Fe(26):1,s,2,2,s,2,2,p,6,3,s,2,3,p,6,3,d,6,4,s,2,Only those electrons which occupy the outermost shell,will involve in chemical reaction;called valence electrons.,-,7,-,Examples(electronic structure,1.2 Bonding,-Metallic bonding,The valence electrons are freely shared by all the,atoms in the structure,Electrons repulse each other keep atoms in certain distance,Electron and nuclei attract each other bonding,Characters:,Close-packed structures in pure metals,Ductility,High electric and thermal conductivity,Shiny,-,8,-,1.2 Bonding-Metallic bondingT,-Ionic bonding,Atom gives up one or more electrons positive charge(Cation),Atom accepts one or more electrons negative charge(Anion),Coulombic attraction force source of ionic bonding,E.g.:NaCl,Na(11):1,s,2,2,s,2,2,p,6,3,s,1,Cl(17):1,s,2,2,s,2,2,p,6,3,s,2,3,p,5,For pure ionic bonding,it would be nondirectional,close-packed.,-,9,-,-Ionic bondingAtom gives up o,The packing pattern of ionic bonding structures:,determined by(i)electrical neutrality,(ii)sizes of ions,Coordination number(CN):,the number of nearest neighbor,atoms/ions surrounding an atom/ion,Not stable,Stable,Determined by the ratio of radius of ions,-,10,-,The packing pattern of ionic b,The packing tends to have as more,CN as possible,2(C+A),2,=(2A),2,+(2A),2,(C+A),2,=2A,2,(C+A)/A=2,1/2,=1.414,C/A=0.414,Example:,NaCl:R,+,=1.02;R,-,=1.81;R,+,/R,-,=1.02/1.81=0.564,CN=6,MgO:R,+,=0.72;R,-,=1.40;R,+,/R,-,=0.72/1.40=0.514,CN=6,SiO,2,:R,+,=0.40;R,-,=1.40;R,+,/R,-,=0.40/1.40=0.286,CN=4,-,11,-,The packing tends to have as m,-Covalent bonding,Two or more atoms share electrons such that each achieves a stable structure,Unlike metallic and ionic bonding,covalent bonding is directional due to shape of orbital,Directional,Not close-packed,sp,3,hybrid orbital,:one,s,orbital and 3,p,orbitals are mixed together to,form four new orbitals.Each orbital points to one corner of tetrahedral,and form angle of 109.5,o,between them.,Hybridization,p,s,C,N,O,Cl,-,12,-,-Covalent bondingTwo or more,sp,2,hybrid orbital,:one,s,orbital and 2,p,orbitals are mixed together to,form three new orbitals.The remaining p orbital is unaffected.Three,sp,2,orbitals are on the same plane and form angle of 120,o,between each other.,The unaffected p orbital perpendicular to the plane,p,s,sp,1,hybrid orbital,:one,s,orbital and one,p,orbitals are mixed together to,form two new orbitals.The remaining two p orbitals are unaffected.Two,sp,1,orbitals are on the same line and form angle of 180,o,between them.,p,s,-,13,-,sp2 hybrid orbital:one s orbi,-Bonding strength/force,-,14,-,The first term is attractive,and the second is repulsive.,At r r,o,the equilibrium value,the repulsive force dominates and U rises.,The force F
展开阅读全文