CHE 101 Lecture Outline CHAPTER 2 Chapter 2 Atoms Molecules Ions MATERIAL TO LEARN ON YOUR OWN I do not have time to cover Sections 2 1 2 2 2 5 in lecture A Pre recorded lecture is located on UB Learns located Gulde Folder PreRecorded Folder Chapter02 Atom History Gulde Folder PreRecorded Folder Chapter02 Periodic Table You MUST watch the periodic table prior to next lecture Turn to Page 10 Today s Atom of lecture Notes Atomic Theory of Matter Greek philosophers posed the questions Can matter be divided into smaller and smaller pieces Is there a point at which there is no more division Democritus 460 370 B C argued matter consisted of indivisible particles called Plato Aristotle said there be indivisible particles the Atomic view John Dalton 1803 1807 Brought back the concept 4 postulates which lead to 3 Atomic Theory Laws 1 CHE 101 Lecture Outline CHAPTER 2 Dalton s 4 Postulates 1 Each element is composed of extremely small particles called 2 All atoms of 1 element are but from the atoms of all other elements 3 Atoms of 1 element into atoms of a different element by chemical reactions rxns atoms are neither nor in chemical rxns 4 Compounds are formed when atoms of element combine in a specific 2 CHE 101 Lecture Outline CHAPTER 2 John Dalton s 3 Atomic Theory Laws 1 Law of definite constant composition the relative number kind of atoms are constant derived from postulate 4 Regardless of source a compound is always the Carbon dioxide CO2 from NY or NJ is the same Both contain same type of atoms Both contain same ratio of atoms Mass percent mass contributes in relation to the total compound mass Ex A 20 0g sample of CO2 containing 5 44g of carbon was collected in NY what is the mass percent of carbon A different 34 7g sample was collected in NJ and is believed to be CO2 It was found to have 9 44g carbon is the second sample CO2 3 CHE 101 Lecture Outline CHAPTER 2 John Dalton s 3 Atomic Theory Laws Cont d In chemical reactions atoms to form NEW chemicals 2 Law of mass conservation the total starting masses the total ending masses derived from postulate 3 Ex Decomposition of water 18g H2O 3 Law of multiple proportions the of the mass ratios of 2 different compounds can be expressed as a Multiple atoms forms multiple compounds H2O vs H2O2 Ex Compound 1 H mass ratio Compound 1 O mass ratio Compound 1 11 2g H and 88 8g O Compound 2 5 9g H and 94 1g O Compound 2 H mass ratio Compound 2 O mass ratio H Ratio O Ratio To find Ratio put mass ratio in numerator Compound b c on top contains more Hydrogen than Compound Compound b c on top contains more Oxygen than Compound 4 CHE 101 Lecture Outline CHAPTER 2 Discovery of Electrons J J Thompson 1897 Cathode ray tube A cathode metal plate emits cathode rays Rays bend a positive a negative electric field when a magnet is turned on Discovered that atoms have particles aka that are charged Millikan 1909 Oil drop experiments Droplets of oil passed through an electrically charged plate an X ray source X rays caused electrons in the air to attach to the oil drops resulting in a charge Discovered that electrons a are charged 1 6x10 19 C b have a 9 10x10 28 g Discovery of the Nucleus Thompson Plum pudding model Atoms are Even distribution of charges throughout the entire atom 5 CHE 101 Lecture Outline CHAPTER 2 Ernest Rutherford 1910 Gold Foil Expt Aimed radiation at sheets of gold foil Particles should go but some OR Atoms are mostly empty space occupied by but in the CENTER is the that contains all the positive charge and nearly all the mass Called the positive particles 6 CHE 101 Lecture Outline CHAPTER 2 MATERIAL TO LEARN PRIOR TO NEXT LECTURE Video Location Gulde Folder PreRecorded Folder Chapter02 Periodic Table Periodic Table Terminology Group family Referred to by or Period Beware of A K A Rare Earth 7 CHE 101 Lecture Outline CHAPTER 2 Types of Elements Determined by line 1 Metals of line Except Hydrogen H nonmetal at room temp except Mercury Hg Properties Lustrous shiny High conductivity electrical thermal Malleable pounded into sheets Ductile drawn into wires 2 Nonmetals of line At room temp 6 solids C P S Se I I2 At 1 liquid Br Br2 11 gasses Properties Solids lustrous conductivity malleable nor ductile 3 Metalloids semimetals touching the line Except Aluminum Al metal Hves properties of but more like side it is on Te more like b c on side Extremely important in chemistry 8 CHE 101 Lecture Outline CHAPTER 2 MUST be able to tell difference b t metal nonmetal Chemical formulas Chemical formula uses numeric to indicate the atoms in a compound A Molecular formula chemical formula that indicates the of atoms in a molecule Benzene C6H6 Acetylene C2H2 Aluminum sulfate Al2 SO4 3 Al atoms S atoms O atoms B Empirical formula chemical formula that give the of atoms in a molecule Benzene Acetylene Aluminum sulfate Many ways to view chemicals Chemical formula CO2 Ball and stick Note typically the atom in the is written Space filling 9 CHE 101 Lecture Outline CHAPTER 2 10 CHE 101 Lecture Outline CHAPTER 2 Today s Atom Atoms are mostly empty space containing a dense called the nucleus Even though very small the nucleus contains nearly all the mass of an atom 3 types of Subatomic particles 1 Protons 1919 Located Inside nucleus Charge 1 Mass 1 amu 2 Neutrons 1932 Located Inside nucleus Charge 0 Mass 1 amu 3 Electrons 1897 Located outside nucleus Charge 1 Mass 0 amu amu atomic mass unit 1amu 1 661x10 27 kg 11 CHE 101 Lecture Outline CHAPTER 2 Atom Terminology Mass A sum of protons neutrons for a specific atom Atomic Z protons in the nucleus unique to each atom Also the number of electrons in a neutral atom Located on the periodic table Nuclear Nuclide Symbols Nuclear symbols describes an atom A Z X 25 12 Mg Protons 12 Neutron 13 Electrons 12 NOTE mass MUST always be written To name a specific atom element name Mass Magnesium 25 Entering into mastering chem Use super subscripts 12 CHE 101 Lecture Outline CHAPTER 2 Ions Ions atoms that gain or lose electrons creating a charge Charge written in upper right If gain electrons negative charge Protons 7 Neutron 8 Electrons 10 If lose electrons positive charge Protons 12 Neutron 13 Electrons 10 Questions 2 1 How many neutrons does an atom have if Atomic 17 Mass 37 has a charge of 1 A 17 B 20 C 37 D 54 2 2 What is the nuclear symbol of an atom if Atomic 17 Mass 37 has a charge of 1 A 37Cl B 37Rb C 37Ca D 17Cl E 20Cl 13 CHE 101 Lecture Outline CHAPTER 2 Isotopes All atoms of a specific element aren t identical The number