1	Chapter 2 Atoms, Molecules, and Ions
2	History Greeks Democritus and Leucippus - atomos Aristotle- elements Alchemy 1660 - Robert Boyle- experimental definition of element. Lavoisier- Father of modern chemistry He wrote the book- used measurement
3	Laws Conservation of Mass Law of Definite Proportion- compounds have a constant composition by mass. They react in specific ratios by mass. Multiple Proportions- When two elements form more than one compound, the ratios of the masses of the second element that combine with one gram of the first can be reduced to small whole numbers.
4	What?! Water has 8 g of oxygen per g of hydrogen. Hydrogen peroxide has 16 g of oxygen per g of hydrogen. 16/8 = 2/1 Small whole number ratios
5	Example of Law Of Multiple Proportions Mercury has two oxides. One is 96.2 % mercury by mass, the other is 92.6 % mercury by mass. Show that these compounds follow the law of multiple proportion. Speculate on the formula of the two oxides.
6	Your Turn Nitrogen and oxygen form two compounds. Show that they follow the law of multiple proportions
7	Dalton’s Atomic Theory 1. Elements are made up of atoms 2. Atoms of each element are identical. Atoms of different elements are different. 3. Compounds are formed when atoms combine. Each compound has a specific number and kinds of atom. 4. Chemical reactions are rearrangement of atoms. Atoms are not created or destroyed.
8	A Helpful Observation Gay-Lussac- under the same conditions of temperature and pressure, compounds always react in whole number ratios by volume. Avagadro- interpreted that to mean at the same temperature and pressure, equal volumes of gas contain the same number of particles (called Avagadro’s hypothesis)
9	Experiments to determine what an atom was J. J. Thomson- used Cathode ray tubes
10	Thomson’s Experiment
11	Thomson’s Experiment
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17	Thomson’s Experiment By adding an electric field
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24	Thomsom’s Model Found the electron Couldn’t find positive (for a while) Said the atom was like plum pudding A bunch of positive stuff, with the electrons able to be removed
25	Millikan’s Experiment
26	Millikan’s Experiment
27	Millikan’s Experiment
28	Millikan’s Experiment
29	Millikan’s Experiment
30	Millikan’s Experiment
31	Millikan’s Experiment
32	Millikan’s Experiment
33	Millikan’s Experiment
34	Radioactivity Discovered by accident Bequerel Three types alpha- helium nucleus (+2 charge, large mass) beta- high speed electron gamma- high energy light
35	Rutherford’s Experiment Used uranium to produce alpha particles Aimed alpha particles at gold foil by drilling hole in lead block Since the mass is evenly distributed in gold atoms alpha particles should go straight through. Used gold foil because it could be made atoms thin
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41	"Atom is mostly empty" Atom is mostly empty Small dense, positive piece at center Alpha particles are deflected by it if they get close enough
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43	Modern View The atom is mostly empty space Two regions Nucleus- protons and neutrons Electron cloud- region where you have a chance of finding an electron
44	Sub-atomic Particles Z - atomic number = number of protons determines type of atom A - mass number = number of protons + neutrons Number of protons = number of electrons if neutral
45	Symbols
46	Chemical Bonds The forces that hold atoms together Covalent bonding - sharing electrons makes molecules Chemical formula- the number and type of atoms in a molecule C₂H₆ - 2 carbon atoms, 6 hydrogen atoms, Structural formula shows the connections, but not necessarily the shape.
47	"Structural Formula" Structural Formula
48	"There are also other model..." There are also other model that attempt to show three dimensional shape Ball and stick (see the models in room) Space Filling
49	Ions Atoms or groups of atoms with a charge Cations- positive ions - get by losing electrons(s) Anions- negative ions - get by gaining electron(s) Ionic bonding- held together by the opposite charges Ionic solids are called salts
50	Polyatomic Ions Groups of atoms that have a charge Yes, you have to memorize them. List on page 65
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52	Metals Conductors Lose electrons Malleable and ductile
53	Nonmetals Brittle Gain electrons Covalent bonds
54	Semi-metals or Metalloids
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62	Naming compounds Two types Ionic - metal and non metal or polyatomics Covalent- we will just learn the rules for 2 non-metals
63	Ionic compounds If the cation is monoatomic- Name the metal (cation) just write the name. If the cation is polyatomic- name it If the anion is monoatomic- name it but change the ending to -ide If the anion is poly atomic- just name it practice
64	Covalent compounds Two words, with prefixes Prefixes tell you how many. mono, di, tri, tetra, penta, hexa, septa, nona, deca First element whole name with the appropriate prefix, except mono Second element, -ide ending with appropriate prefix Practice
65	More Naming
66	Ionic compounds If the cation is monoatomic- Name the metal (cation) just write the name. If the cation is polyatomic- name it If the anion is monoatomic- name it but change the ending to -ide If the anion is poly atomic- just name it practice
67	Ionic Compounds Have to know what ions they form off table, polyatomic, or figure it out CaS K₂S AlPO₄ K₂SO₄ FeS CoI₃
68	Ionic Compounds Fe₂(C₂O₄) MgO MnO KMnO₄ NH₄NO₃ Hg₂Cl₂ Cr₂O₃
69	Ionic Compounds KClO₄ NaClO₃ YBrO₂ Cr(ClO)₆
70	Naming Covalent Compounds Two words, with prefixes Prefixes tell you how many. mono, di, tri, tetra, penta, hexa, septa, nona, deca First element whole name with the appropriate prefix, except mono Second element, -ide ending with appropriate prefix Practice
71	Naming Covalent Compounds CO₂ CO CCl₄ N₂O₄ XeF₆ N₄O₄ P₂O₁₀
72	Writing Formulas Two sets of rules, ionic and covalent To decide which to use, decide what the first word is. If is a metal or polyatomic use ionic. If it is a non-metal use covalent
73	Ionic Formulas Charges must add up to zero get charges from table, name of metal ion, or memorized from the list use parenthesis to indicate multiple polyatomics
74	Ionic Formulas Sodium nitride sodium- Na is always +1 nitride - ide tells you it comes from the table nitride is N^-3
75	Ionic Formulas Sodium nitride sodium- Na is always +1 nitride - ide tells you it comes from the table nitride is N^-3 doesn’t add up to zero
76	Ionic Formulas Sodium nitride sodium- Na is always +1 nitride - ide tells you it comes from the table nitride is N^-3 doesn’t add up to zero Need 3 Na
77	Ionic Compounds Sodium sulfite calcium iodide Lead (II) oxide Lead (IV) oxide Mercury (I) sulfide Barium chromate Aluminum hydrogen sulfate Cerium (IV) nitrite
78	Covalent compounds The name tells you how to write the formula duh Sulfur dioxide diflourine monoxide nitrogen trichloride diphosphorus pentoxide
79	More Names and formulas
80	Acids Substances that produce H⁺ ions when dissolved in water All acids begin with H Two types of acids Oxyacids non oxyacids
81	Naming acids If the formula has oxygen in it write the name of the anion, but change ate to -ic acid ite to -ous acid Watch out for sulfuric and sulfurous H₂CrO₄ HMnO₄ HNO₂
82	Naming acids If the acid doesn’t have oxygen add the prefix hydro- change the suffix -ide to -ic acid HCl H₂S HCN
83	Formulas for acids Backwards from names If it has hydro- in the name it has no oxygen anion ends in -ide No hydro, anion ends in -ate or -ite Write anion and add enough H to balance the charges.
84	Formulas for acids hydrofluoric acid dichromic acid carbonic acid hydrophosphoric acid hypofluorous acid perchloric acid phosphorous acid
85	Hydrates Some salts trap water crystals when they form crystals these are hydrates. Both the name and the formula needs to indicate how many water molecules are trapped In the name we add the word hydrate with a prefix that tells us how many water molecules
86	Hydrates In the formula you put a dot and then write the number of molecules. Calcium chloride dihydrate = CaCl₂·2H₂O Chromium (III) nitrate hexahydrate = Cr(NO₃)₃· 6H₂O