《Atomic structure： .ppt》由会员分享，可在线阅读，更多相关《Atomic structure： .ppt（54页珍藏版）》请在三一办公上搜索。
1、Atomic Structure and Relative Masses,1.1The Atomic Nature of Matter1.2The Experimental Evidence of Atomic Structure1.3Sub-atomic Particles1.4Atomic Number,Mass Number and Isotopes1.5Mass Spectrometer1.6Relative Isotopic,Atomic and Molecular Masses,The Atomic Nature of Matter,What is“atom”?,1.1 The a
2、tomic nature of matter(SB p.2),The Greek philosopher Democritus,Iron,1.1 The atomic nature of matter(SB p.2),These are iron atoms!,Daltons atomic theory,John Dalton proposed his Daltons atomic theory,1.1 The atomic nature of matter(SB p.2),Main points of Daltons atomic theory,1.1 The atomic nature o
3、f matter(SB p.2),5.Atoms of different elements combine to form a compound.The numbers of various atoms combined bear a simple whole number ratio to each other.,1.All elements are made up of atoms.,2.Atoms can neither be created nor destroyed.,3.Atoms of the same element are identical.They have the s
4、ame mass and chemical properties.,4.Atoms of different elements are different.They have different masses and chemical properties.,The Experimental Evidence of Atomic Structure,1.2 The experimental evidence of atomic structure(SB p.3),Discovery of electrons,A beam of rays came out from the cathode an
5、d hit the anodeHe called the beam cathode rays,1.2 The experimental evidence of atomic structure(SB p.4),The beam was composed of negatively charged fast-moving particles.,1.2 The experimental evidence of atomic structure(SB p.4),Measure the mass to charge ratio(m/e)of the particles produced,Indepen
6、dent of the nature of the gas inside the discharge tube,1.2 The experimental evidence of atomic structure(SB p.4),Thomsons atomic model,An atom is electrically neutral,1.2 The experimental evidence of atomic structure(SB p.4),How are the particles distributed in an atom?,An atom was a positively cha
7、rged sphereNegatively charged electrons embedded in it like a raisin pudding,1.2 The experimental evidence of atomic structure(SB p.4),Gold foil scattering experiment,performed by Ernest Rutherford,1.2 The experimental evidence of atomic structure(SB p.4),He bombarded a thin gold foil with a beam of
8、 fast-moving-particles(+ve charged),Observation:most-particles passed through the foil without deflectionvery few-particles were scattered or rebounded back,1.2 The experimental evidence of atomic structure(SB p.5),Interpretation of the experimental results,The condensed core is called nucleusThe po
9、sitively charged particle is called proton,1.2 The experimental evidence of atomic structure(SB p.5),Rutherfords atomic model,Expectation:Mass of atom=Total mass of protons,1.2 The experimental evidence of atomic structure(SB p.5),Chadwicks atomic model,presence of neutronsproved by James Chadwick,C
10、hadwicks atomic model,1.2 The experimental evidence of atomic structure(SB p.5),Sub-atomic Particles,Sub-atomic particles,1.3 Sub-atomic particles(SB p.6),3 kinds of sub-atomic particles:ProtonsNeutronsElectrons,Lets Think 1,A carbon-12 atom,1.3 Sub-atomic particles(SB p.7),Characteristics of sub-at
11、omic particles,1.3 Sub-atomic particles(SB p.6),Relative size of the atom and the nucleus,1.3 Sub-atomic particles(SB p.6),Lets Think 2,Atomic Number,Mass Number and Isotopes,Atomic number,1.4 Atomic number,mass number and isotopes(SB p.7),The atomic number(Z)of an element is the number of protons c
12、ontained in the nucleus of the atom.,WHY?,Mass number,1.4 Atomic number,mass number and isotopes(SB p.8),The mass number(A)of an atom is the sum of the number of protons and neutrons in the nucleus.,Atomic numbers and mass numbers of some common atoms,1.4 Atomic number,mass number and isotopes(SB p.
13、8),Isotopes,1.4 Atomic number,mass number and isotopes(SB p.8),Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.,Lets Think 3,1.4 Atomic number,mass number and isotopes(SB p.8),e.g.the two isotopes of chlorine are written as:,OR labelled as Cl-
14、35 and Cl-37.,1.4 Atomic number,mass number and isotopes(SB p.9),Isotopes of some common elements,Mass Spectrometer,1.5 Mass spectrometer(SB p.10),Mass spectrometer,A highly accurate instrument!,Mass spectrometer consists of 6 parts:,1.5 Mass spectrometer(SB p.10),Mass spectrum of Cl2:,1.8 Mass spec
15、trometer(SB p.21),Mass spectrum of CH3Cl:,1.8 Mass spectrometer(SB p.21),Relative Isotopic,Atomic and Molecular Masses,1.9 Relative isotopic,atomic and molecular masses(SB p.22),Relative isotopic mass,The relative isotopic mass of a particular isotope of an element is the relative mass of one atom o
16、f that isotope on the carbon-12 scale.,e.g.relative isotopic mass of Cl-35=35relative isotopic mass of Cl-37=37,1.9 Relative isotopic,atomic and molecular masses(SB p.22),What is carbon-12 scale?,Mg has the same mass as two C-12 atoms,use carbon-12 as the reference standard,Relative atomic mass,The
17、relative atomic mass of an element is the weighted average of the relative isotopic masses of its natural isotopes on the carbon-12 scale.,1.9 Relative isotopic,atomic and molecular masses(SB p.23),1.9 Relative isotopic,atomic and molecular masses(SB p.23),What is the relative atomic mass of Cl?,The
18、 relative abundances of Cl-35 and Cl-37 are 75.77 and 24.23 respectively,Relative atomic mass of Cl=35.48,Relative molecular mass,1.9 Relative isotopic,atomic and molecular masses(SB p.23),The relative molecular mass is the relative mass of a molecule on the carbon-12 scale.,1.9 Relative isotopic,at
19、omic and molecular masses(SB p.23),What is the relative molecular mass of CH3Cl?,Relative molecular mass of CH3Cl=50.50,The END,Check Point 1-1,What does the word“atom”literally mean?Which point of Daltons atomic theory is based on the law of conservation of mass proposed by Lavoisier in 1774 which
20、states that matter is neither created nor destroyed in the course of a chemical reaction?Which point of Daltons atomic theory is based on the law of constant proportion proposed by Proust in 1799 which states that all pure samples of the same chemical compound contain the same elements combined toge
21、ther in the same proportions by mass?,1.1 The atomic nature of matter(SB p.3),(a)Indivisible,(b)Atoms can neither be created nor destroyed.,(c)Atoms of different elements combine to form a compound.The numbers of various atoms combined bear a simple whole number ratio to each other.,Back,Answer,Chec
22、k Point 1-2,Atoms were found to be divisible.What names wer given to the particles found inside the atoms?Give the most important point of the following experiments:(i)E.Goldsteins gas discharge tube experiment;(ii)J.J.Thomsons cathode ray tube experiment;(iii)E.Rutherfords gold foil scattering expe
23、riment.,1.2 The Experimental evidence of atomic structure(SB p.4),(a)Electron,proton and neutron,(b)(i)Discovery of cathode rays(ii)Discovery of electrons(iii)Discovery of nucleus in atoms,Back,Answer,The identity of an element is determined by the number of which sub-atomic particle?,Lets Think 1,B
24、ack,1.3 Sub-atomic particles(SB p.6),The identity of an element is determined by the number of protons in its atomic nucleus.,Answer,Check Point 1-3,Which part of the atom accounts for almost all the mass of that atom?(b)The mass of which sub-atomic particle is often assumed to be zero?,1.3 Sub-atom
25、ic Particles(SB p.7),(a)Nucleus,(b)Electron,Back,Answer,Are there any sub-atomic particles other than protons,neutrons and electrons?,Lets Think 2,Back,1.3 Sub-atomic particles(SB p.7),Other than the three common types of sub-atomic particles(proton,neutron and electron),there are also some sub-atom
26、ic particles called positron(anti-electron)and quark.,Answer,If bromine has two isotopes,79Br and 81Br,how many physically distinguishable combinations of Br atoms are there in Br2?,Lets Think 3,Back,1.3 Sub-atomic particles(SB p.7),There are three physically distinguishable combinations of Br atoms
27、(79Br79Br,79Br81Br and 81Br81Br)in Br2.,Answer,Check Point 1-4,Write the symbol for the atom that has an atomic number of 11 and a mass number of 23.How many protons,neutrons and electrons does this atom have?,1.4 Atomic number,mass number and isotopes(SB p.8),Back,11 protons,12 neutrons,11 electron
28、s.,Answer,Check Point 1-5,Label the different parts of the mass spectrometer.,1.5 Mass spectrometer(SB p.12),Back,A Vaporization chamberB Ionization chamberC Accelerating electric fieldD Deflecting magnetic fieldE Ion detector,Answer,The mass spectrum of neon is given below.Determine the relative at
29、omic mass of neon.,1.5 Mass spectrometer(SB p.12),Back,Example 1-6,Relative atomic mass of neon=20.18,Answer,Check Point 1-6,(a)The mass spectrum of lead is given below.Given that the relative atomic mass of lead is 207.242,calculate the relative abundance of the peak at m/e of 208.,1.6 Relative iso
30、topic,atomic and molecular masses(SB p.14),Let x be the relative abundance of the peak at m/e of 208.(204 1.5+206 23.6+207 22.6+208x)(1.5+23.6+22.6+x)=207.242x=52.3The relative abundance of the peak at m/e of 208 is 52.3.,Answer,Check Point 1-6,(b)The mass spectrum of dichloromethane is given below.
31、Calculate the relative molecular mass of dichloromethane.,Back,1.6 Relative isotopic,atomic and molecular masses(SB p.14),The relative molecular mass of dichloromethane=(84 94+85 3.0+86 59+87 2.2+88 13+89 2.5+90 0.8)(94+3.0+59+2.2+13+2.5+0.8)=85.128The relative molecular mass of dichloromethane is 85.128.,Answer,
