logging in or signing up Atomic Theory and atomic structure1 marmich Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 829 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: September 18, 2009 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... By: nehajatin (12 month(s) ago) nice 1 Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Atomic Theory & Atomic Structure : Atomic Theory & Atomic Structure Early Atomic Theories : Early Atomic Theories Democritis (400 BCE) : Democritis (400 BCE) First to propose idea of atom Atom = “a” + “tomos” = cannot be cut Based solely on logic; not supported by experiments Alchemy(12-1500 CE) : Alchemy(12-1500 CE) Modern word ‘chemistry’ came from Arabic ‘alkimiya’ recognized importance of experimentation Responsible for developing lab equipment & procedures still used today Galileo(~1600 CE) : Galileo(~1600 CE) Birth of modern science - combining logic, experimenting, publishing results Lavosier & Priestly(1700’s) : Lavosier & Priestly(1700’s) Quantitative analysis of chemicals Law of Conservation of Mass: Matter can neither be created nor destroyed Proust(1700’s) : Proust(1700’s) Developed Law of Definite Proportions Law of Definite Proportions: Different samples of the same compound always contain its constituent elements in the same proportions by mass Law of Definite Proportions : Law of Definite Proportions Copper carbonate always contains 5.3 parts copper 4 parts oxygen 1 part carbon by mass Dalton(1800’s) : Dalton(1800’s) School teacher that proposed the first modern-day idea of atoms Law of Multiple Proportions: If 2 elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in small whole # ratios Law of Multiple Proportions : Law of Multiple Proportions Dalton’s Atomic Theory - 1808 : Dalton’s Atomic Theory - 1808 All matter is composed of atoms which cannot be subdivided Atoms of same element are identical (size, mass, reactivity) Atoms combine to form compounds in simple, whole # ratios Chemical reactions involve the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction Modern Atomic Theories : Modern Atomic Theories Electric Charges : Electric Charges Objects with an equal amount of positive and negative charge are said to be electrically neutral + – positive negative Forces between Charges : Forces between Charges Objects with like charge repel Objects with opposite charge attract Forces between Charges : Forces between Charges Electrostatic force becomes greater the more charge Electrostatic force becomes smaller the greater the distance between the charges Thompson : Thompson Discovered the electron Determined the charge-to-mass ratio of an electron Cathode Ray Experiments : Cathode Ray Experiments Any metal worked for anode Negative electric field repelled beam Object placed in path of glow blocked beam Evidence & Conclusions : Evidence & Conclusions cathode rays consisted of subatomic particles from atoms of anode cathode rays are negatively charged \ must also be positive charge Millikan calculated electron’s mass to be 9.11 x 10-31 kg Thompson’s Atomic Model : Thompson’s Atomic Model The Gold Foil Experiment: Setup : The Gold Foil Experiment: Setup The Gold Foil Experiment: Hypothesis : The Gold Foil Experiment: Hypothesis The α-particles will pass straight through the atoms The Gold Foil Experiment: Outcome : The Gold Foil Experiment: Outcome What’s happening? : What’s happening? The Gold Foil Experiment: Conclusions : The Gold Foil Experiment: Conclusions Atoms : must be mostly space must have a very small, dense area of + charge Protons have same charge as e-, but almost 2000x more mass! Rutherford’s Problems : Rutherford’s Problems How is nucleus held together? Why don’t electrons collapse into nucleus? H atom has 1 proton & He atom has 2 protons, \ mass ratio should be 2:1; instead the ratio is 4:1 …there must be another particle The Neutron : The Neutron Discovered by James Chadwick in 1932. Neutron is electrically neutral & has slightly greater mass than a proton Mystery solved. Updating Dalton’s Atomic Theory : Updating Dalton’s Atomic Theory 3 major differences between modern atomic theory & Dalton’s atomic theory: Atoms are NOT indivisible – they are made up of protons, neutrons, and electrons Atoms of the same element are NOT exactly alike – they can have different masses (isotopes) Atoms CAN be changed from one element to another, but not by chemical reactions (nuclear reactions) Atomic Structure & Isotopes : Atomic Structure & Isotopes Modern View of Atomic Structure : Modern View of Atomic Structure + 0 Modern View of Atomic Structure : Modern View of Atomic Structure + 0 Atomic Mass Unit (amu) : Atomic Mass Unit (amu) defined as a more convenient unit for reporting mass of small numbers of atoms 12C is used as the reference 1 amu is defined as exactly 1/12 of a 12C atom Getting Information from the Periodic Table : Getting Information from the Periodic Table 6 C 12.0111 Atomic # = # p+ in nucleus Elemental symbol Atomic mass (more on this later) Isotopic Notation : Isotopic Notation Atomic number (Z) = # of p+ in the nucleus Mass number (A) = sum of # p+ & n0 in nucleus For a neutral atom, # e- = # p+ Examples : Mass number (A) Examples Atomic number (Z) Isotopes : Isotopes All atoms in an element have the same atomic number However, 2 atoms of the same element can have different mass numbers – called isotopes Isotopes have: Same # of p+ Different # of no Some Common Isotopes : Some Common Isotopes Relative Abundance : Relative Abundance Mass Spectrometry : Mass Spectrometry Technique used to determine atomic mass Mass Spectrometry, cont. : Mass Spectrometry, cont. Ions are accelerated through a magnetic field Amount of deflection depends on the ion’s mass Highest mass deflected least Lowest mass deflected most Mass Spectrometry, cont. : Mass Spectrometry, cont. Mass (amu) Sample mass spec for chlorine Relative abundance of each isotope can be determined from relative peak heights 35 37 Relative Abundance & Atomic Mass : Relative Abundance & Atomic Mass Relative isotopic abundance is then used to calculate atomic mass Atomic mass is the weighted average of the mixture of isotopes Example : Example average atomic mass = (atomic mass 35Cl)(fraction 35Cl) + (atomic mass 37Cl)(fraction 37Cl) = (34.968 amu)(0.7577) + (36.965 amu)(0.2423) = 35.45 amu Calculate the atomic mass of Cl given the relative abundances of its isotopes: 35Cl – 75.77% 37Cl – 24.23% Practice : Practice Copper, a metal known since ancient times, is used in electrical cables & pennies, among other things. The atomic masses of its 2 stable isotopes, 63Cu (69.09%) and 65Cu (30.91%) are 62.93 amu and 64.9278 amu, respectively. Calculate the average atomic mass of copper – the relative abundances of each ion is given in parentheses. Answer: 63.54 amu The Bohr Model : The Bohr Model Electromagnetic Spectrum : Electromagnetic Spectrum Light : Light c = lu c = speed of light (3.0 x 108 m) l = wavelength u = frequency Frequency vs. Wavelength : Frequency vs. Wavelength Light : Light Energy as frequency Energy as wavelength Light behaves like a particle (photon) as well as a wave c = lu Emission Spectrums : Emission Spectrums When electricity is run through a sample of hydrogen gas, hydrogen atoms gain energy H atoms loose that energy by emitting photons Resulting spectrum is discontinuous continuous discontinuous What’s happening? : What’s happening? Bohr Model : Bohr Model Electrons move in circular orbits around the nucleus Only certain energy levels are “permitted” (this explains the discrete lines for the emission spectrum of hydrogen) The Mole : The Mole The Mole : The Mole Fundamental SI unit for measuring the amount of a substance Defined by Avogodro’s number Contains 6.022045 x 1023 particles (atoms, molecules, ions, etc.) Mass of one mole of atoms of an element = its atomic mass in grams The Mole vs. The Dozen : The Mole vs. The Dozen dozen – the amount of a substance that contains 12 units Mole – the amount of a substance that contains 6.022 x 1023 units The Mole vs. The Dozen : The Mole vs. The Dozen a dozen apples = 12 apples 1 mole He atoms = 6.022 x 1023 He atoms) 1 dozen apples = 5 kg 1 mol He atoms = 4.0026 g Example : Example How many moles of He are in 6.46 g He? How many atoms? 6.46 g He 6.46 g He Molar Mass : Molar Mass Synonymous with molecular mass & molecular weight The mass in grams of one mole of a compound Sum of all the atomic masses of all the atoms in a molecule For ionic compounds, referred to as formula mass; calculated in same way as molar mass Example #1 : Example #1 Calculate the # of moles of chloroform (CHCl3) in 198 g of chloroform Molecular mass of chloroform: 1 mol C = 12.01 g C 1 mol H = 1.008 g H 3 mol Cl = 3(35.46 g) = 106.38 g Cl 1 mol CHCl3 = 119.47 g CHCl3 198 g CHCl3 You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
Atomic Theory and atomic structure1 marmich Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 829 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: September 18, 2009 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... By: nehajatin (12 month(s) ago) nice 1 Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Atomic Theory & Atomic Structure : Atomic Theory & Atomic Structure Early Atomic Theories : Early Atomic Theories Democritis (400 BCE) : Democritis (400 BCE) First to propose idea of atom Atom = “a” + “tomos” = cannot be cut Based solely on logic; not supported by experiments Alchemy(12-1500 CE) : Alchemy(12-1500 CE) Modern word ‘chemistry’ came from Arabic ‘alkimiya’ recognized importance of experimentation Responsible for developing lab equipment & procedures still used today Galileo(~1600 CE) : Galileo(~1600 CE) Birth of modern science - combining logic, experimenting, publishing results Lavosier & Priestly(1700’s) : Lavosier & Priestly(1700’s) Quantitative analysis of chemicals Law of Conservation of Mass: Matter can neither be created nor destroyed Proust(1700’s) : Proust(1700’s) Developed Law of Definite Proportions Law of Definite Proportions: Different samples of the same compound always contain its constituent elements in the same proportions by mass Law of Definite Proportions : Law of Definite Proportions Copper carbonate always contains 5.3 parts copper 4 parts oxygen 1 part carbon by mass Dalton(1800’s) : Dalton(1800’s) School teacher that proposed the first modern-day idea of atoms Law of Multiple Proportions: If 2 elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in small whole # ratios Law of Multiple Proportions : Law of Multiple Proportions Dalton’s Atomic Theory - 1808 : Dalton’s Atomic Theory - 1808 All matter is composed of atoms which cannot be subdivided Atoms of same element are identical (size, mass, reactivity) Atoms combine to form compounds in simple, whole # ratios Chemical reactions involve the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction Modern Atomic Theories : Modern Atomic Theories Electric Charges : Electric Charges Objects with an equal amount of positive and negative charge are said to be electrically neutral + – positive negative Forces between Charges : Forces between Charges Objects with like charge repel Objects with opposite charge attract Forces between Charges : Forces between Charges Electrostatic force becomes greater the more charge Electrostatic force becomes smaller the greater the distance between the charges Thompson : Thompson Discovered the electron Determined the charge-to-mass ratio of an electron Cathode Ray Experiments : Cathode Ray Experiments Any metal worked for anode Negative electric field repelled beam Object placed in path of glow blocked beam Evidence & Conclusions : Evidence & Conclusions cathode rays consisted of subatomic particles from atoms of anode cathode rays are negatively charged \ must also be positive charge Millikan calculated electron’s mass to be 9.11 x 10-31 kg Thompson’s Atomic Model : Thompson’s Atomic Model The Gold Foil Experiment: Setup : The Gold Foil Experiment: Setup The Gold Foil Experiment: Hypothesis : The Gold Foil Experiment: Hypothesis The α-particles will pass straight through the atoms The Gold Foil Experiment: Outcome : The Gold Foil Experiment: Outcome What’s happening? : What’s happening? The Gold Foil Experiment: Conclusions : The Gold Foil Experiment: Conclusions Atoms : must be mostly space must have a very small, dense area of + charge Protons have same charge as e-, but almost 2000x more mass! Rutherford’s Problems : Rutherford’s Problems How is nucleus held together? Why don’t electrons collapse into nucleus? H atom has 1 proton & He atom has 2 protons, \ mass ratio should be 2:1; instead the ratio is 4:1 …there must be another particle The Neutron : The Neutron Discovered by James Chadwick in 1932. Neutron is electrically neutral & has slightly greater mass than a proton Mystery solved. Updating Dalton’s Atomic Theory : Updating Dalton’s Atomic Theory 3 major differences between modern atomic theory & Dalton’s atomic theory: Atoms are NOT indivisible – they are made up of protons, neutrons, and electrons Atoms of the same element are NOT exactly alike – they can have different masses (isotopes) Atoms CAN be changed from one element to another, but not by chemical reactions (nuclear reactions) Atomic Structure & Isotopes : Atomic Structure & Isotopes Modern View of Atomic Structure : Modern View of Atomic Structure + 0 Modern View of Atomic Structure : Modern View of Atomic Structure + 0 Atomic Mass Unit (amu) : Atomic Mass Unit (amu) defined as a more convenient unit for reporting mass of small numbers of atoms 12C is used as the reference 1 amu is defined as exactly 1/12 of a 12C atom Getting Information from the Periodic Table : Getting Information from the Periodic Table 6 C 12.0111 Atomic # = # p+ in nucleus Elemental symbol Atomic mass (more on this later) Isotopic Notation : Isotopic Notation Atomic number (Z) = # of p+ in the nucleus Mass number (A) = sum of # p+ & n0 in nucleus For a neutral atom, # e- = # p+ Examples : Mass number (A) Examples Atomic number (Z) Isotopes : Isotopes All atoms in an element have the same atomic number However, 2 atoms of the same element can have different mass numbers – called isotopes Isotopes have: Same # of p+ Different # of no Some Common Isotopes : Some Common Isotopes Relative Abundance : Relative Abundance Mass Spectrometry : Mass Spectrometry Technique used to determine atomic mass Mass Spectrometry, cont. : Mass Spectrometry, cont. Ions are accelerated through a magnetic field Amount of deflection depends on the ion’s mass Highest mass deflected least Lowest mass deflected most Mass Spectrometry, cont. : Mass Spectrometry, cont. Mass (amu) Sample mass spec for chlorine Relative abundance of each isotope can be determined from relative peak heights 35 37 Relative Abundance & Atomic Mass : Relative Abundance & Atomic Mass Relative isotopic abundance is then used to calculate atomic mass Atomic mass is the weighted average of the mixture of isotopes Example : Example average atomic mass = (atomic mass 35Cl)(fraction 35Cl) + (atomic mass 37Cl)(fraction 37Cl) = (34.968 amu)(0.7577) + (36.965 amu)(0.2423) = 35.45 amu Calculate the atomic mass of Cl given the relative abundances of its isotopes: 35Cl – 75.77% 37Cl – 24.23% Practice : Practice Copper, a metal known since ancient times, is used in electrical cables & pennies, among other things. The atomic masses of its 2 stable isotopes, 63Cu (69.09%) and 65Cu (30.91%) are 62.93 amu and 64.9278 amu, respectively. Calculate the average atomic mass of copper – the relative abundances of each ion is given in parentheses. Answer: 63.54 amu The Bohr Model : The Bohr Model Electromagnetic Spectrum : Electromagnetic Spectrum Light : Light c = lu c = speed of light (3.0 x 108 m) l = wavelength u = frequency Frequency vs. Wavelength : Frequency vs. Wavelength Light : Light Energy as frequency Energy as wavelength Light behaves like a particle (photon) as well as a wave c = lu Emission Spectrums : Emission Spectrums When electricity is run through a sample of hydrogen gas, hydrogen atoms gain energy H atoms loose that energy by emitting photons Resulting spectrum is discontinuous continuous discontinuous What’s happening? : What’s happening? Bohr Model : Bohr Model Electrons move in circular orbits around the nucleus Only certain energy levels are “permitted” (this explains the discrete lines for the emission spectrum of hydrogen) The Mole : The Mole The Mole : The Mole Fundamental SI unit for measuring the amount of a substance Defined by Avogodro’s number Contains 6.022045 x 1023 particles (atoms, molecules, ions, etc.) Mass of one mole of atoms of an element = its atomic mass in grams The Mole vs. The Dozen : The Mole vs. The Dozen dozen – the amount of a substance that contains 12 units Mole – the amount of a substance that contains 6.022 x 1023 units The Mole vs. The Dozen : The Mole vs. The Dozen a dozen apples = 12 apples 1 mole He atoms = 6.022 x 1023 He atoms) 1 dozen apples = 5 kg 1 mol He atoms = 4.0026 g Example : Example How many moles of He are in 6.46 g He? How many atoms? 6.46 g He 6.46 g He Molar Mass : Molar Mass Synonymous with molecular mass & molecular weight The mass in grams of one mole of a compound Sum of all the atomic masses of all the atoms in a molecule For ionic compounds, referred to as formula mass; calculated in same way as molar mass Example #1 : Example #1 Calculate the # of moles of chloroform (CHCl3) in 198 g of chloroform Molecular mass of chloroform: 1 mol C = 12.01 g C 1 mol H = 1.008 g H 3 mol Cl = 3(35.46 g) = 106.38 g Cl 1 mol CHCl3 = 119.47 g CHCl3 198 g CHCl3