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Periodic Table Organization
Dmitri Mendeleev is the “father of the periodic table” elements arranged by atomic number 7 periods (rows) for electron energy levels 18 groups/families (columns) contain elements with similar properties Notice location of: metals, nonmetals, metalloids (semimetals) solids, liquids, and gases natural and artificially made elements radioactive elements
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Symbol The Element Boxes
atomic number: number of protons in the nucleus, defines an element (equal to the number of electrons in a neutral atom) Symbol atomic number symbol: one or two letter code for an element. Symbols do not always match the names. mass number or atomic mass mass number: number of protons + number of neutrons in an isotope atomic mass: weighted average mass of the natural isotopes of an element.
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alkali metals alkaline earth metals transition metals rare earth or inner transition metals metalloids or semimetals other metals
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noble gases halogens other nonmetals
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Diatomic elements H2, N2, O2, F2, Cl2, Br2, I2
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number of valence electrons by group (family)
1 number of valence electrons by group (family) 8 2 3 4 5 6 7
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+1 oxidation numbers by group (family) +4 -4 +2 +3 -3 -2 -1 variable +
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Periodic Table Trends Atomic number increases Atomic size decreases
Metallic properties decrease Energy to remove an electron increases Atomic number, atomic size, and metallic properties increase Energy to remove an electron decreases Periodic Table Trends
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General Properties of Metals
Metals account for about 75% of the elements Solids at room temperature (except mercury) Lustrous (shiny, reflect light) Malleable (can be shaped) Ductile (can be stretched) Good conductors of heat and electricity Give up electrons easily
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Group 1 & 2 Metals Alkalis Alkaline-earths Li Na K Rb Cs Fr Be Mg Ca
3 11 19 37 55 87 lithium sodium potassium rubidium cesium francium Alkalis Softest metals 1 valence electron easy to remove +1 oxidation Most reactive metals React strongly with water Not found pure Form basic solutions Alkaline-earths Harder than alkalis 2 valence electrons easy to remove +2 oxidation Less reactive React with water Not found pure Form basic solutions Be Mg Ca Sr Ba Ra 4 12 20 38 56 88 beryllium magnesium calcium strontium barium radium
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Groups 3-12 Metals Transition Metals
Biggest subdivision of the periodic table Harder than groups 1 & 2 Less reactive than groups 1 & 2 Higher melting and boiling points than groups 1 & 2 Variable valence & oxidation Often form colorful solutions Precious metals (silver, gold, platinum) Iron, cobalt, and nickel are magnetic
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Inner Transition Metals (Rare Earth)
Belong in the periodic table but are taken out to allow the table to fit on one page Consist of lanthanides and actinides Many are man-made and radioactive Some have magnetic properties Used in superconductors Fluoresce under UV
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Metalloids (Semi-metals)
Similar in appearance to metals but have different crystal structures. Sometimes react like metals and sometimes non-metals depending on the chemicals they are reacting with B Si Ge As Sb Te 5 14 32 33 51 52 boron silicon germanium arsenic antimony tellerium Po 84 polonium At 85 astatine Semiconductors are made from silicon, boron, and germanium. Semiconductors only conduct electricity under special conditions. Used to make electronic devices like computers, calculators, MP3 players.
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General Properties of Nonmetals
Good insulators (poor conductors) Solids are brittle Solids are dull (no luster) 3 - 8 valence electrons Gain electrons easily (except noble gases)
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Other Nonmetals C N P S Se O H
6 7 15 16 34 carbon nitrogen phosphorus sulfur selenium O 8 oxygen H 1 hydrogen These elements form compounds that are the basis of life: DNA, sugars, fats, proteins, and water. Hydrocarbons are used for heating, cooking, and transportation fuels. Graphite and diamonds are both forms of carbon. Nitrogen and oxygen are the primary components of air. Phosphorus is used in matches. Sulfur is used in fertilizers and many manufacturing processes
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Halogens - Group 17 7 valence electrons Highly reactive group F
F is the most reactive element Used in water purification, antiseptics, bleaches, pesticides, and photographic processes. F Cl Br I 9 17 35 53 fluorine chlorine bromine iodine At 85 astatine
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Noble Gases - Group 18 Non-reactive (inert) Full outer shells
2 He Non-reactive (inert) Full outer shells Low m.p.s and b.p.s Used in lights, lasers, welding, and cryogenic research. helium 10 Ne neon 18 Ar argon 36 Kr krypton 54 Xe xenon 86 Rn radon
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