《基础化学》英文教学课件：chapter-9.ppt

1、Chapter 9.9-1.Fundamentals 9-2.Structure of Hydrogen Atom 9-3.Quantum Numbers and Atomic Orbitals 9-4.Electron Configurations and PeriodicityHow are the electrons distributed in this space?what are the electrons doing in the atom?1.Fundamentals.An atom is an extremely small particle of matter that r

2、etains its identity during chemical reactions.Postulates of Daltons atomic theory(1803)Fe on Cu(111)Xe on Ni(110)Single atoms can be visualized and manipulated by scanning-tunneling microscope(STM,).1.Fundamentals is a type of matter composed of only one kind of atom,each atom of a given kind having

3、 the same properties.Na,Cl2.is a type of matter composed of atoms of two or more elements chemically combined in fixed proportions.NaCl,H2O.consists of the of the atoms present in the reactants to give new chemical combinations present in the products.Atoms are not created,destroyed,or broken into s

4、maller particles by any chemical reaction.NaCl2ClNa22John Dalton 约翰约翰道尔顿道尔顿(1766-1844)England atomic theory1.Fundamentals1.FundamentalsJ.J.Thomson(18561940)English 约瑟夫约瑟夫汤姆逊汤姆逊Nobel Prize(Physics),1906Raisin bread model(1904)In 1897,Thomson discovered electrons,by which he proposed the raisin bread

5、model()of atoms.Discovery of electronMarie Curie 玛丽玛丽居里居里(1867-1934)Poland Nobel Prize(Physics),1903 (Chemistry),1911polonium,Po,84 radium,Ra,88 Henri Becquerel亨利亨利贝克勒尔贝克勒尔(1852-1908)France Nobel Prize(Physics),1903Discovery of Radioactivity uranium,U,92 1.FundamentalsWilliam Thomson,1st Baron Kelvi

6、n 威廉威廉汤姆森，第一代开尔文男爵汤姆森，第一代开尔文男爵(18241907)British 热力学之父热力学之父William Thomson,1st Baron Kelvin 威廉威廉汤姆森，第一代开尔文男爵汤姆森，第一代开尔文男爵(18241907)British 热力学之父热力学之父E.Rutherford欧内斯特欧内斯特卢瑟福卢瑟福(18711937)New Zealand Nobel Prize,1908ChemistryDiscovery of protonFather of nuclear physics1.Fundamentals1.Fundamentals1.Fundam

7、entalsAn atom consists of two kinds of particles:a positively()-charged (),which contains most()of the atoms mass,and.An electron is a negatively()-charged particle that exists in the region()around the nucleus.1.FundamentalsAccording to Rutherfords model,an atom consists of a nucleus many times sma

8、ller than the atom itself,with electrons occupying the remaining space.Rutherfords model posed a dilemma.According to the nuclear model,an electron would(1)continuously lose energy as electromagnetic radiation(photons);(2)spiral into the nucleus(in about 10-10 s).2.Structure of Hydrogen Atom(1)conti

9、nuous energy:continuous wavelength:continuous spectrum;(2)the atom would“die”.2.Structure of Hydrogen AtomI.Continuous vs.line spectrum()White light,entering at the left,strikes a prism,which disperses the light into a continuous spectrum of wavelength.A heated (such as a heated tungsten filament(钨钨

10、丝丝)emits light with(a spectrum containing light of all wavelengths).2.Structure of Hydrogen Atom The lines corresponds to visible light()emitted by atoms.A heated emits light with(a spectrum showing only certain colors or specific wavelengths of light).2.Structure of Hydrogen Atom2.Structure of Hydr

11、ogen AtomIn 1885 showed that the wavelengths in the visible spectrum of hydrogen could be reproduced by a simple formula:)n121(m101.09712217Here greater than 2.The wavelengths of the four lines in the hydrogen atom visible spectrum correspond to n=3,4,5,and 6,respectively.Max Planck 马克斯马克斯普朗克普朗克(185

12、81947)GermanNobel prize,1918PhysicsPlanck postulate Josiah Willard Gibbs威拉德威拉德吉布斯吉布斯(18391903)USAGibbs entropy2.Structure of Hydrogen AtomE=n h2.Structure of Hydrogen AtomAlbert Einstein 阿尔伯特阿尔伯特爱因斯坦爱因斯坦(1879-1955)Nobel prize,1929PhysicsPhotoelectric effect2.Structure of Hydrogen AtomConsider this a

13、nalogy to help see why light of insufficient energy cannot free an electron from a metal surface.If one Ping-Pong ball does not have enough energy to knock a book off its shelf,neither does a series of Ping-Pong balls,because the book cannot save up the energy from the individual impacts.But one bas

14、e-ball traveling at the same speed does have enough energy to move the book.Whereas the energy of a ball is related to its mass and velocity,the energy of a photon is related to its frequency.2.Structure of Hydrogen AtomII.The Bohr Theory of the Hydrogen Atom(1913)To account for:(1)The of the hydrog

15、en atom(that the atom exists and the electron does not continuously radiate energy and spiral into the nucleus);(2)The of the atom.N.Bohr尼尔斯尼尔斯玻尔玻尔(1885-1962)DenmarkNobel prize(1922)Bohr modelN.Bohr尼尔斯尼尔斯玻尔玻尔(1885-1962)DenmarkNobel prize(1922)2.Structure of Hydrogen AtomAn electron can have only spe

16、cific energy values in an atom,which are called its.J102.18R18H1,2,3,4n,nRE2Hground state()excited states()n:principal quantum number()2.Structure of Hydrogen Atom1,2,3,4,n,nRE2HThe energies have values because the energy of the separated nucleus and electron is taken to be zero.As the nucleus and e

17、lectron come together to form a stable state of the atom,energy is released and the energy becomes less than zero,or negative.2.Structure of Hydrogen Atom2.Structure of Hydrogen AtomAn electron in an atom can change energy only by going from one energy level to another energy level.By doing so,the e

18、lectron undergoes a.2.Structure of Hydrogen AtomAn electron in a higher energy level(initial energy level Ei)undergoes a transition to a lower energy level(final level Ef).ifEhE)n1n1(R)nR()nR(EEh2i2fH2fH2iHfic/)n1n1(hcR12i2fHJ102.179R18HsJ106.626h3418sm102.998c)n1n1(m101.09712i2f172.Structure of Hyd

19、rogen AtomExample 9-1:What is the wavelength of light emitted when the electron in a hydrogen atom undergoes a transition from energy level n=4 to level n=2?Solution:)n1n1(m101.09712i2f17)4121(m101.097221716m102.06(blue-green)nm486m1048692.Structure of Hydrogen Atom)n121(m101.09712i217Balmer series(

20、visible):)n131(m101.09712i217Paschen series(infrared):)n111(m101.09712i217Lyman series(ultraviolet):2.Structure of Hydrogen AtomThe nucleus is composed of two different kind of particles,protons(),and neutrons().P Pa ar rt ti ic cl le e MMa as ss s (k kg g)C Ch ha ar rg ge e (C C)Electron 9.10939 10

21、-31-1.60218 10-19 Proton 1.67262 10-27 1.60218 10-19 Neutron 1.67493 10-27 0 2.Structure of Hydrogen AtomJ.Chadwick詹姆斯詹姆斯查德威克查德威克(18911974)Nobel Prize,1935PhysicsDiscovery of the neutron2.Structure of Hydrogen AtomEvaluation of Bohrs theory The theory firmly established the concept of atomic energy

22、level.It can account for(1)the of the hydrogen atom and(2)the of the atom.The theory was unsuccessful,however,in accounting for the details of atomic structure and in predicting energy levels for.2.Structure of Hydrogen AtomIII.Wave-particle duality(of the electronAccording to Einstein,light has not

23、 only wave properties,which we characterize by frequency and wavelength,but also particle properties.For example,a particle of light,photon,has momentum.This momentum,mc,is related to the wavelength of the light:mch2mcE hE hmc2hchmc2.Structure of Hydrogen AtommhLouis de Broglie reasoned that if ligh

24、t(considered as a wave)exhibits particle aspects,then perhaps particles of matter show characteristics of waves under the proper circumstances.He therefore postulated that a particle of matter of mass m and speed has a wavelength,by analogy with light:L.de Broglie路易路易维克多维克多德布罗意德布罗意(1892-1987)FranceN

25、obel prize(1929)Wave nature of electrons 2.Structure of Hydrogen AtommhAn (9.110-31 kg)moving at about 5.9105 ms-1 has a wavelength of about 1.210-9 m.mh2mh1A (0.60 kg)moving at about 10 ms-1 has a wavelength of about 10-34 m.11234sm10kg0.60smkg106.626m101.13415311234sm105.9kg109.1smkg106.626nm1.2m1

26、01.292.Structure of Hydrogen Atom2.Structure of Hydrogen AtomThey showed that electrons gave a diffraction pattern()when reflected from a crystal or pass through a very thin gold foil.Both Thomson received Nobel prizes:J.J.for showing that the electron is a particle and G.P.for showing that it is a

27、wave.The wave property of electrons was demonstrated by C.Davisson,L.H.Germer and G.P.Thomson(son of J.J.Thomson).Ernst Ruska恩斯特恩斯特鲁斯卡鲁斯卡 (1906 1988)GermanNobel Prize,(1986)PhysicsElectron Microscopy E.Ruska used this wave property to construct the first electron microscope()in 1933.Shown is the sca

28、nning electron microscope image of a wasps head.2.Structure of Hydrogen Atom2.Structure of Hydrogen AtomYou cannot say that the electron will be at a particular position at a given time,we can say that the electron is to be at this point.Wave property of electrons:statements about where we would fin

29、d the electron(of finding an electron at a certain point in an atom).2.Structure of Hydrogen AtomDe Broglie relation says that electrons can not be treated only as particles.In some circumstances,they demonstrate wave properties,which must be considered to uncover the atomic structures.mh IV.Uncerta

30、inty Principle2.Structure of Hydrogen AtomIt is impossible to know simultaneously,with absolute precision,both the position and the momentum of a particle such as an electron.W.Heisenberg维尔纳维尔纳海森伯海森伯(1901-1976)GermanyNobel prize(1932)Uncertainty Principle 2.Structure of Hydrogen Atom The product of

31、the uncertainty in position and the uncertainty in momentum of a particle can be no smaller than Planks constant divided by 4.4)(hpxx x:The uncertainty in the x coordinate of a particle;px:The uncertainty in the momentum in the x direction.If you know very well where a particle is,you can not know w

32、here it is going!2.Structure of Hydrogen Atom4)(hpxxm1011%sm106kg109.14smkg106.626m4hx916311234For an with a velocity of 6.0106 ms-1(an error of 1%):m1091%sm10kg0.604smkg106.626m4hx3411234For a with a velocity of 10 ms-1(an error of 1%)The uncertainty principle is only significant for particles of v

33、ery small mass such as electrons.mpx2.Structure of Hydrogen AtomHeisenbergs uncertainty principle says that,for electrons,the uncertainties in position and momentum are normally quite large.We can not describe the electron in an atom as moving in a definite orbit.4)(hpxxV.Wave Function（）2.Structure

34、of Hydrogen AtomIn 1926,E.Schrdinger devised a theory(Schrdinger equation)that could be used to find the wave properties of electrons in atoms and molecules.E.Schrdinger埃尔文埃尔文薛定谔薛定谔(1887-1961)AustriaNobel prize(1933).It cannot be applied directly to an electron in an atom,where the electron is subje

35、ct to the attractive force of the nucleus.Schrdinger equation 2.Structure of Hydrogen Atom2.Structure of Hydrogen Atom is contained in a mathematical expression called,denoted by the Greek letter,.The wave function is obtained by solving Schrdinger equation:EVm222,gives the probability of finding an

36、 electron within a region of space.The diagram shows the (at a point)for an electron in a hydrogen atom in the ground state.2.Structure of Hydrogen Atom2.Structure of Hydrogen Atom2.Structure of Hydrogen AtomThe graph shows the (within a spherical shell)of finding the electron within shells at vario

37、us distances from the nucleus.The curve exhibits a maximum(r=52.9 pm,),which means that the radial probability is greatest for a given distance from the nucleus.drr4(r)222.Structure of Hydrogen AtomInformation about an electron in an atom is contained in a wave function,which can just be obtained by

38、 solving me under specific conditions.Solve me,and you get everything the states of electrons in an atom.EVm2223.Quantum Numbers and Atomic OrbitalsInformation about electron in an atom is contained in a,different quantum numbers are needed because there are dimensions to space.ml,n,ml,n,wave functi

39、ons is obtained by solving Schrdinger equation.For solving Schrdinger equation,(n,l,m)specify a wave function,n,l,m.3.Quantum Numbers and Atomic Orbitalsorbitalatomicml,n,Probability density for an electron in a hydrogen atom in the ground state.An atomic orbital is pictured qualitatively by describ

40、ing the region of space where there is high probability(99%)of finding the electrons.The atomic orbital so pictured has a definite shape.I.Quantum numbers3.Quantum Numbers and Atomic Orbitals The smaller n is,the lower the energy.In the case of the hydrogen atom(single electron),n is the only quantu

41、m number determining the energy.For other atoms,the energy also depends to a slight extent on the l quantum number.2HnREGeneral meaning:This quantum number is the one on which the of an electron in an atom principally depends;it can have any:1,2,3,and so on.3.Quantum Numbers and Atomic Orbitals n al

42、so determines the of electron to the nucleus or the size of an orbital.The larger the value of n is,the larger the orbital,or the farer the distance of an electron to the nucleus.Orbitals of the same quantum state n are said to belong to the same.Shells are sometimes designated by the following lett

43、ers:LetterKLMNOPQn12345673.Quantum Numbers and Atomic OrbitalsThis quantum number distinguish orbitals of given n having different shapes,it can have.n=1:l=0 n=2:l=0,1 n=3:l=0,1,2 n=4:l=0,1,2,3 3.Quantum Numbers and Atomic OrbitalsLetterspdfl0123 Orbitals of the same n but different l are said to be

44、long to different of a given shell.The different subshells are usually denoted by letters as follows:The choice of letter symbols for quantum numbers survives from old spectroscopic terminology(describing the lines in a spectrum as sharp,principal,diffuse,and fundamental).3.Quantum Numbers and Atomi

45、c Orbitals To denote a subshell within a particular shell,we write the value of the n for the shell,followed by the letter designation for the subshell.For example,2p denotes a subshell with quantum numbers n=2 and l=1.The of an orbital also depends somewhat on the l quantum number(except for the H

46、atom).For a given n,the energy of an orbital increases with l.energy(n,l)Within each shell of quantum number n,there are different kinds of orbitals,each with a distinctive denoted by an l quantum number.3.Quantum Numbers and Atomic Orbitalsn=1:l=0(s);1s.n=2:l=0(s),1(p);2s,2p.n=3:l=0(s),1(p),2(d);3s

47、,3p,3d.3.Quantum Numbers and Atomic OrbitalsThis quantum number distinguish orbitals of given n and lthat is,of given energy and shape but having a;the allowed Every value denotes an individual atomic orbital.l=0(s):m=0;There is only one orbital in the s subshell.3.Quantum Numbers and Atomic Orbital

48、sl=1(p):m=-1,0,1;There are three different orbitals in the p subshell.l=2(d):m=-2,-1,0,1,2;There are five different orbitals in the d subshell.There is no direct relation between the values of m and the x,y,z designation of the orbitals.3.Quantum Numbers and Atomic OrbitalsNote that there are 2l+1 o

49、rbitals in each subshells of quantum number l.These orbitals have the same shape and energy,though with different orientation in space,thus called.orbitalatomicml,n,3.Quantum Numbers and Atomic OrbitalsThis quantum number refers to the 3.Quantum Numbers and Atomic OrbitalsThe first three quantum num

50、bers characterize the orbital that describe the region of space where an electron is most likely to be found;we say that the electron“occupies”this orbital.The spin quantum number describes the spin orientation of the electron.Each electron in an atom has the principal quantum number(n),the angular