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Published byBuck Reed Modified over 9 years ago
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The Periodic Table
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Atomic Structure Nucleus- center of an atom -contains protons - which are positive -contains neutrons- which are neutral Electrons (which are negative) surround the nucleus in energy levels 1 st energy level = holds 2e 2 nd energy level = holds 8e 3 rd energy level = holds 18e 4 th energy level = holds 32e
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Bohr Model of Atom
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More Chemistry tidbits Atomic number = number of protons Mass number = # protons + # neutrons #Neutrons = mass number - # protons # protons = # electrons
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Isotopes Isotopes are different atoms of the same element that contain the same number of protons but different number of neutrons. Examples Cl-35 vs. Cl-37 17P 17P 18N 20N
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Periodic Table tidbits Period table organization – organized by increasing atomic number Split into metals (left side of stair step line) and nonmetals (right side of stair step line) Metalloids- surround the stairstep line Groups (families) – vertical columns (#1- 18) Periods – horizontal rows (#1-7)
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Metals-left side of table Exist as solids at room temperature Shiny Good conductors of heat & electricity Malleable (can be bent)
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Nonmetals-right side of table Most are gases at room temperature Some are brittle solids- carbon, sulfur, iodine, & phosphorus Most do not conduct heat & electricity well
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Metalloids- next to zigzag line b/w metals & nonmetals Properties fall between neighbors on both sides Most are silvery in appearance, brittle, poor conductors of heat & electricty
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Transition elements Metals- which are less reactive than the alkali or alkaline earth metals Often exist as oxide or sulfide ores ex. Iron sulfide or iron oxide
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Major Groups on periodic table Alkali metals- group 1- most reactive Alkaline earth metals- group 2 Transition metals- groups 3-12 Metalloids- surround stairstep line Halogens- group 17 Noble gases-group 18 (inert gases-stable; nonreactive) Periodic table
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Chemical Bonding Octet Rule- Atoms bond with one another in order to become stable (need to get 8 electrons in outer ring) Exception- hydrogen only needs 2 electrons in outer ring to be stable Bonds are forces of attraction between elements Involves bonding of valence electrons (electrons in outermost shell)
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Lewis Dot Structures Lewis dot diagrams- display the number of valence electrons (outermost electrons) around the element symbol Used to show how atoms of different elements bond and form compounds Hint- use group number to find valence electrons
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Electron configurations
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Lewis Dot Diagrams
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