4 4 Early day scientists - Greeks were the first to try and explain chemical changes. Believed that all matter consisted of four basic things. (fire, air, water and earth)
5 5 Democritus Greek, 460-370 B.C. Created the word atomus (atom) Believed everything was composed of atoms Proposed that the world is made up of empty space and atoms. He believed everything was composed of this and the atom was indivisible.
6 6 Alchemy - A pseudo science, purpose of the science was to attempt to make gold. Such elements as Hg, S, and Sb were discovered due to this science.
7 7 John Dalton (1766- 1844) - English - first to prepare a table of relative atomic weights and the Law of multiple proportions. Dalton’s early day symbols
8 8 Law of multiple Proportions - when two elements form a series of compounds, the ratios of the masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers. Ex: NO and NO 2
10 10 Dalton's Atomic Theory - 1. Each element is made up of tiny particles called atoms. 2. The atoms of a given element are identical; the atoms of different elements are different in some fundamental way or ways. 3. Chemical compounds are formed when atoms combine with each other. A given compound always has the same relative numbers and types of atoms. 4. Chemical reactions involve reorganization of the atoms -- changes in the way they are bound together. The atoms themselves are not changed in a chemical reaction.
11 11 J.J. Thomson English, (1856 - 1953) In 1897 discovered the particle the electron. Discovered it by using a cathode ray.
12 12 What charge does an electron have? Negative
13 13 Cathode Ray Tube A stream of electrons is produced at the negative pole of an applied electric field. The electron was isolated using this device.
14 14 J.J. Thomson, measured mass/charge of e - (1906 Nobel Prize in Physics) 2.2
15 15 George J. Stoney Irish, 1826-1911 In 1891, he proposed the term 'electron' to describe the fundamental unit of electrical charge, and his contributions to research in this area laid the foundations for the eventual discovery of the particle by J.J. Thomson in 1897.electronJ.J. Thomson Don’t take down
16 16 The modern view of the atom was developed by Ernest Rutherford of New Zealand (1871-1937).
17 17 1. 1.atoms positive charge is concentrated in the nucleus 2. 2.proton (p) has opposite (+) charge of electron 3. 3.mass of p is 1840 x mass of e - (1.67 x 10 -24 g) particle velocity ~ 1.4 x 10 7 m/s (~5% speed of light) (1908 Nobel Prize in Chemistry) 2.2
18 18 Ernest Rutherford Canterbury University in Christchurch, NZ Rutherford laboratory
20 20 Ernest Rutherford New Zealand, ( 1871 - 1937) Named the alpha and beta particles and the gamma ray. Named the proton and is known for the use of the foil method to detect the proton. Conducted the gold foil experiment, which led to the discovery of the nucleus
21 21 James Chadwick English, (1891-1974) Isolated the neutron in 1932.
23 23 ATOM COMPOSITION protons and neutrons in the nucleus.protons and neutrons in the nucleus. the number of electrons is equal to the number of protons.the number of electrons is equal to the number of protons. electrons in space around the nucleus.electrons in space around the nucleus. extremely small. One teaspoon of water has 3 times as many atoms as the Atlantic Ocean has teaspoons of water.extremely small. One teaspoon of water has 3 times as many atoms as the Atlantic Ocean has teaspoons of water. The atom is mostly empty space
24 24 Proton - comes from the Greek meaning " the primary one". Positive charged particle equal in magnitude to the electron's negative charge. Mass = 1.672623 x 10 -24 g.
25 25 Atomic Number tells the number of protons. 13 Al 26.981 Atomic number Atom symbol Atomic weight
26 26 Neutron - neutrally charged particle which has the same mass as the proton. Mass = 1.674926 x 10 -24 g. To find the number of neutrons (Mass # - Atomic # = # neutron)
27 27 Electron - Negatively charged particle found orbiting the nucleus of the atom. An atom's activity is primarily determined by the electron. Occupies most of the atom's volume. In a neutral atom, # of electrons = # protons.
28 28 ATOMIC COMPOSITION Summary ProtonsProtons –+ electrical charge –mass = 1.672623 x 10 -24 g –relative mass = 1.007 atomic mass units (u) ElectronsElectrons – negative electrical charge –relative mass = 0.0005 u NeutronsNeutrons – no electrical charge –mass = 1.009 u
29 29 Antoine Lavoisier French, (1743 - 1794) First to truly explain the true nature of combustion. Used quantitative measurements in his experiments, which led to the Law of conservation of mass.
30 30 Antoine Lavoisier Lavoisier named phlogiston (oxygen). The word oxygen comes from the Greek meaning " to form an acid". Was beheaded during the French Revolution.
31 31 Law of conservation of mass - states that mass is neither created nor destroyed.
32 32 Joseph Proust French, (1754 - 1826) Came up with the principle known as the Law of definite proportions.
33 33 Law of Definite Proportions States that a compound always contains exactly the same proportions of elements by weight.
34 34 Benjamin Franklin American (1706 - 1790) Discovered two types of electric charge. He named them positive and negative. Experiments showed that like charges repel each other and unlike charges attract each other.
37 37 Georg Baurer 1500’s - German Development of metallurgy
38 38 Paracelsus – 1500’s - Swiss Studied the medicinal application of minerals.
39 39 Robert Boyle English, (1627- 1691) First person to perform truly quantitative physical experiments.
40 40 Georg Stahl (1660-1734) German Believed a substance called phlogiston flowed out of burning materials.
41 41 Joseph Priestley (1733- 1804) English First to isolate “Phloiston”, oxygen, by heating mercuric oxide. First to observe graphite as an electrical conductor.
42 42 Priestley Observed a gas being given off during the fermentation of grains, (CO 2 ), this gas could be dissolved in water to make a drink called seltzer.
43 43 Atomic Weight This tells us the mass of one atom of an element relative to one atom of another element.This tells us the mass of one atom of an element relative to one atom of another element. Tells the number of protons and neutrons in an atom.Tells the number of protons and neutrons in an atom. The average mass of an element.The average mass of an element. Standard = carbonStandard = carbon
44 44 Question What is the atomic weight of Tin? 118.71
45 45 What is the atomic number of Antimony? 51
47 47 Joseph Guy- Lussac (1778-1850) French Performed experiments in which he measured the volume of gases if the temperature and pressure were held constant. 1808 - He was the co- discoverer of boron.boron
48 48 1804 - He and Jean- Baptiste Biot made a hot-air balloon ascent to a height of 6.4 kilometres in an early investigation of the Earth's atmosphere. He wanted to collect samples of the air at different heights to record differences in temperature and moisture.Jean- Baptiste BiotEarth's atmosphere
49 49 Particles in a Mole 6.02214199 x 10 23 Avogadro’s Number There is Avogadro’s number of particles in a mole of any substance. Amedeo Avogadro 1776-1856
50 50 Amadeo Avogadro Italian, (1776 - 1856) Avogadro's Hypothesis - states that at the same temperature and pressure, equal volumes of different gases contain the same number of particles.
53 53 Jons Jakob Berzelius Swedish, (1779 -1848 ) Discovered elements Si, Ce, Th, Se. Came up with 50 accurate masses for elements known at the time. Invented a simple set of symbols for the elements.
54 54 Robert Millikan American, 1868-1953 Measured the charge of the electron thus enabling scientists to measure the mass of the electron to be 9.11 x 10 -31 g.
55 55 e - charge = -1.60 x 10 -19 C Thomson’s charge/mass of e - = -1.76 x 10 8 C/g e - mass = 9.10 x 10 -28 g Measured mass of e - (1923 Nobel Prize in Physics) 2.2
56 56 Henri Becquerel French (late 1800's) Did the very first studies with radioactive elements.
57 57 Radioactivity The emission of radiation, decay of nucleus to form a different nucleus.The emission of radiation, decay of nucleus to form a different nucleus.
61 61 Radioactive Particles Alpha – has a +2 charge, a charge twice that of the electron and with opposite sign. A piece of paper will deflect it.
62 62 Radioactive Particles Beta – High speed electron. A piece of aluminum foil will deflect it.
63 63 Radioactive Particles Gamma – High energy light. One foot of solid concrete will stop it.
64 64 Nucleus Center of atom containing the proton and neutron. Makes up most of the atom’s mass. Protons and neutrons are very tightly packed in the nucleus. Very dense.
65 65 Pierre and Marie Curie Poland-(1867-1934), France-(1859 - 1906) Worked to isolate polonium and radium from pitch blend. Marie is the only person to have won the Nobel Peace Prize in Science twice.
66 66 Michael Faraday English (1791- 1867) Showed that the same quantity of electric current caused different quantities of different metals to deposit, and postulated that those quantities were related to the relative masses of the atoms of those elements.
68 68 Atomic Mass Unit (amu) - equals 1/12th of the mass of an atom of carbon with 6 protons and 6 neutrons. (To convert to grams use 1.661 x 10 -24 g = 1 amu)
69 69 Problem : How many neutrons, electrons, and protons does the following element have and what is this element? 238 92 X (The top number tells the atomic mass and the bottom number the atomic number. P+ = 92 E- = 92 No = 238-92 = 146 The element is Uranium.
70 70 Problem: What is the mass number of a fluorine atom with ten neutrons? Such an atom has a mass of 18.9984 amu. What is the mass in grams? 9 p + + 10 n o = mass number 19. (18.9984) 18.9984 amu 1.661 x 10 -24 g amu =3.156 x 10 -23 g
71 71 Hey mom he doesn’t have feathers. It’s fur, f-u-r.
72 72 Isotopes - atoms with the same number of protons but different number of neutrons. Ex: 26 12 Mg would have 14 neutrons.
73 73 Find the number of neutrons. 108 46 Pd Is this an isotope? Why or why not?
74 74 Isotopes Atoms of the same element (same Z) but different mass number (A).Atoms of the same element (same Z) but different mass number (A). Boron-10 has 5 p and 5 n: 10 5 BBoron-10 has 5 p and 5 n: 10 5 B Boron-11 has 5 p and 6 n: 11 5 BBoron-11 has 5 p and 6 n: 11 5 B 10 B 11 B
75 75 Hydrogen Isotopes Hydrogen has _____ isotopes 11H11H11H11H 21H21H21H21H 31H31H31H31H 1 proton and 2 neutrons, tritium radioactive 1 proton and 1 neutron, deuterium 1 proton and 0 neutrons, protium
77 77 Isotopes & Their Uses Heart scans with radioactive technetium-99. 99 43 Tc Emits gamma rays
78 78 Masses of Isotopes determined with a mass spectrometer
79 79 Isotopes Because of the existence of isotopes, the mass of a collection of atoms has an average value.Because of the existence of isotopes, the mass of a collection of atoms has an average value. Average mass = ATOMIC WEIGHTAverage mass = ATOMIC WEIGHT Boron is 19.9% 10 B and 80.1% 11 B. That is, 11 B is 80.1 percent abundant on earth.Boron is 19.9% 10 B and 80.1% 11 B. That is, 11 B is 80.1 percent abundant on earth. For boron atomic weightFor boron atomic weight = 0.199 (10.0 u) + 0.801 (11.0 u) = 10.8 u = 0.199 (10.0 u) + 0.801 (11.0 u) = 10.8 u 10 B 11 B
80 80 Isotopes & Atomic Weight Because of the existence of isotopes, the mass of a collection of atoms has an average value.Because of the existence of isotopes, the mass of a collection of atoms has an average value. 6 Li = 7.5% abundant and 7 Li = 92.5% 6 Li = 7.5% abundant and 7 Li = 92.5% –Atomic weight of Li = ______________ 28 Si = 92.23%, 29 Si = 4.67%, 30 Si = 3.10% 28 Si = 92.23%, 29 Si = 4.67%, 30 Si = 3.10% –Atomic weight of Si = ______________
81 81 Problem: Silver has 2 isotopes, one with 60 neutrons and the other with 62 neutrons. What are the mass numbers and symbols of these isotopes? 107 47 Ag and 109 47 Ag
82 82 Problem Bromine has 2 naturally occurring isotopes, one with a mass of 78.918336 amu and a percent abundance of 50.69%. The other isotope, of mass 80.916289 amu has a percent abundance of 49.31 %. Calculate the atomic mass of bromine. (.5069 x 78.918336 amu) + (.4931 x 80.916289 amu) = 79.90 amu
83 83 Enrico Fermi Italian, 1901-1954 Successfully split an uranium atom in the first nuclear fission reaction
84 84 Niels Bohr Danish, (1885 - 1962) Compared the motion of electrons to the motion of the planets orbiting the sun. Electrons in motion enable them to overcome the attraction of the positive attraction of the nucleus.
85 85 Period Group Alkali Metal Noble Gas Halogen Alkali Earth Metal 2.4
109 109 Periods - run horizontal and period number tells the number of energy levels.
110 110 Metals - have such properties as shiny, conduct electricity, and heat, malleable and ductile. Tend to lose electrons and therefore carry a positive charge. Located left of the zig-zag line.
111 111 Ductile - metals can be drawn into wires.
112 112 Malleable - metals can be hammered into thin sheets.
113 113 Non - metals - Located right of zig - zag line. Tend to gain electrons and therefore tend to carry a negative charge.
115 115 Metalloids - have properties of both metals and non - metals. Located along zig - zag line. B, Si, Ge, As, Sb, Te
116 116 Dmitri Mendeleev Russian, (1834 - 1907) Arranged the elements on the periodic table according to their properties and atomic weight. Others who suggested some form of periodic table were Chancourtois, Newland, and Meyer.
117 117 Periodic Table Dmitri Mendeleev developed the modern periodic table. Argued that element properties are periodic functions of their atomic weights.Dmitri Mendeleev developed the modern periodic table. Argued that element properties are periodic functions of their atomic weights. We now know that element properties are periodic functions of their ATOMIC NUMBERS.We now know that element properties are periodic functions of their ATOMIC NUMBERS.
118 118 H.G. Moseley English (1887 - 1915) Arranged the elements according to atomic #. Died in WWI
119 119 HydrogenHydrogen Shuttle main engines use H 2 and O 2
120 120 Allotropes - when an element can often exist in several different and very distinct forms. Ex: Carbon - graphite, coal and diamond.
121 121 Oxygen - most abundant element in the earth's crust.
122 122 Selenium - Se Studies have shown that areas having a soil content high in selenium tend to have lower cancer rates. Found in the heart muscle.
123 123 Silicon - Si - second most abundant element in the earth's crust. Most of the earth's rocks sand and soil are made up of SiO 2. Silicon has helped make computer solid state circuitry.
124 124 Sulfur - S - ancient times called "brimstone“. Found in two states TX and LA.
126 126 Nitrogen - most abundant element in the earth's atmosphere.
127 127 Iron - found in hemoglobin helps in carrying O 2.
128 128 Americium - used in smoke detectors in the U.S.
129 129 Bismuth - last element in Periodic Table that is not radioactive.
130 130 Phosphorus Phosphorus first isolated by Brandt from urine, 1669 exists as P 4 in nature, white phosphorus.
131 131 Boron in Death Valley Death Valley has been a major source of borax ( a washing powder )and other boron-containing minerals.Death Valley has been a major source of borax ( a washing powder )and other boron-containing minerals. Borax was transported out of Death Valley, where it was mined by wagons pulled by teams of 20 mules.Borax was transported out of Death Valley, where it was mined by wagons pulled by teams of 20 mules.
132 132 Gems & Minerals Sapphire: Al 2 O 3 with Fe 3+ or Ti 3+ impurity gives blue whereas V 3+ gives violet.Sapphire: Al 2 O 3 with Fe 3+ or Ti 3+ impurity gives blue whereas V 3+ gives violet. Ruby: Al 2 O 3 with Cr 3+ impurityRuby: Al 2 O 3 with Cr 3+ impurity
133 133 Distillation - is a widely used method for separating mixtures, mostly liquids, based on differences in their boiling points. A liquid is boiled, capturing and cooling the resultant hot vapors, and collecting the condensed vapors.
134 134 Simple Distillation: Apparatus Put in boiling stone!
135 135 Correct Thermometer Placement Thermometer must be below this level