材料学基础1.ppt

材料科学基础Fundamental of MaterialsProf:Tian Min Bo Tel:62795426，62772851 E-mail:Department of Material Science and EngineeringTsinghua University.Beijing 100084Lesson oneMaterials Science deals with the relationship between the macroscopic properties and the microscopic structures.1.1 Atomic structureuu.Atomic numbers and atomic masses 1.Atomic Models 1.Atomic ModelsChapter IAtomic Structure and Bonding2.Atomic numbers The atomic number of an atom indicates the number of protons(positively charged particles)which are in its nucleus,and in a neutral atom the atomic number is also equal to the number of electrons in its charge cloud.All the elements have been classified according to electron configuration in the periodic table.The periodic tableThe periodic tableIA碱金属碱金属碱土金属碱土金属过渡元素过渡元素01HIIA主族金属主族金属非金属非金属稀有气体稀有气体IIIAIVAVAVIAVIIAHe2LiBe轻稀土金属轻稀土金属重稀土金属重稀土金属贵金属贵金属BCNOFNe3NaMgIIBIVBVBVIBVIIBVIIBIBIIBAlSiPSClAr4KCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKr5RbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXe6CsBaLaHfTaWReOsIrPtAuHgTlPbBiPoAtRn7FrRaAcRfDbSgBhHsMtUunUuuUub镧系镧系LaCePrNdPmSmEuGdTbDyHoErTmYbLu锕系锕系AcThPaUNpPuAmCmBkCfEsFmMdNoLr3.Atomic mass The relative atomic mass of an element is the mass in grams of 6.0231023 atoms(Avogadros number NA)of that element.uu.The electronic structure of atoms 1.Quantum numbers 1.Quantum numbers Quantum numbers are the numbers in an atom that assign electrons to discrete energy levels.The energy level to which each electron belongs is determined by four quantum numbers.The principal quantum number n The subsidiary quantum number l The magnetic quantum number ml Electron spin quantum number ms2.Atomic size.Atomic size3.Electron configurations.Electron configurations Pauli exclusion principlePauli exclusion principle This principle stipulates that each electron This principle stipulates that each electron state can hold no more than two electrons,state can hold no more than two electrons,which must have opposite spins.which must have opposite spins.Electrons with the same subsidiary quantum number have as many parallel spins as possible.3.Electronegativity.Electronegativity Electronegative elements are nonmetallic in nature and accept electrons in chemical reactions to produce negative ions,or anions.Electronegativity describes the tendency of an atom to gain an electron.Example problem 1.1Example problem 1.1Calculate the energy in joules(J)and electron volts(eV)of the photon whose wavelength is 121.6 nanometers(nm).(1.00eV=1.6010-19J;h=6.6310-34JS;1 nm=10-9m)SolutionSolutionExamples and DiscussionsExerciseThank you!1