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Periodic table
 

Periodic table

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    Periodic table Periodic table Presentation Transcript

    • Periodic Table• Dmitri Mendeleev-recognized that elements had repeating patterns (periodic) and organized elements into a table by increasing atomic mass• With table he was able to predict that there would be elements still unidentified by the gaps in his table
    • • Henry Moseley - determined that the number of protons - atomic number (which is unique to each element) would allow the elements to fit into very specific pattern• All identified elements follow the periodic law – chemical and physical properties change periodically with atomic number
    • Metals• Most elements are metals• Found to the left of the zigzag line• Solid at room temp (exception: mercury and hydrogen – nonmetal)• Properties: – Shiny – Ductile – Malleable – Good conductors
    • Metalloids• Also called semiconductors• Border the zigzag line (exception Al)• Have properties of both metals and nonmetals depending on the conditions• properties: depending on conditions – Brittle – Good conductors – Some shiny (others dull)
    • nonmetals• More than half are gases at room temp• To the right of the zigzag line• Properties:• Not malleable or ductile• Not shiny or dull• Poor conductors
    • Each square on table• Each square includes:• elements name• chemical symbol (color coded to identify if element is a solid, liquid or gas at room temp)• Atomic number (protons)• Atomic mass• Background color (identifies metals, nonmetals and metalloids on table)
    • • First letter of chemical symbol is always upper case and any additional letters are lower case• Newest elements have temporary 3 letter symbols• Rows (left to right) are called periods- determines the number of energy levels• Properties gradually change moving left to right across each row from reactive (group 1) to non- reactive (group 18)
    • • Columns are called groups or family• Elements in the same group or family have similar properties moving up and down each column• Each element in a family has the same number of valence electrons in the outer shell• Group number determine the valence electrons (ex: group one – all elements in group 1 have 1 valence electron, all of the elements in group 2 have 2 valence and so on)
    • Energy Levels• 1st energy level – 2 valence electrons (max)• 2nd energy level – 8 valence electrons (max)• 3rd energy level – 8 valence electrons (max)• And so on….• Each energy level can have less valence electrons but they can not have more than the maximum valence electrons.
    • Bonds• To form bonds, elements must reach a full state of 8 valence electrons in the outermost energy level (octet rule) (Exception: would be first energy level which is full at 2-helium)
    • Group 1: Alkali metals• Metals• 1 valence electron in outer level (easily shared and form compounds easily)• Very reactive with H2O, O2 and other elements• Don’t appear in nature by themselves, only as compounds
    • Group 2 – Alkaline-Earth Metals• Metals• 2 valence electrons in outer level (slightly less reactive)
    • Group 3 – 12: Transition• Metals• 1 or 2 valence electrons in outer level (depending on element) and are less reactive
    • Lanthanides and Actinides• In periods 6 and 7 and appear at the bottom of the periodic table to keep table from being to wide• Lanthanides are shiny reactive metals• Actinides are unstable radioactive• All elements after Pu-94 (plutonium) are man-made in labs and don’t occur in nature
    • Group 13: Boron Group• Has 1 metalloid and 4 metals• 3 valence electrons in outer level and are semi reactive
    • Group 14-Carbon group• 1 nonmetal, 2 metalloids and 2 metal• 4 valence electrons in outer level and most non-reactive depending on element• Forms organic compounds (all living things contain carbon)
    • Group 15-Nitrogen Group• 2 nonmetals, 2 metalloids, 1 metal• 5 valence electrons in outer level and reactivity depends on conditions and element• P is extremely reactive and only appears in compounds
    • Group 16-Oxygen Group• 3 nonmetals, 1 metalloid, and 1 metal• 6 valence electrons in outer level and reactivity depends on element – Po-84 is radioactive
    • Group 17-Halogens• Nonmetals• 7 valence electrons in outer level and has violent reactions with alkali-metals to form salt compounds – Highly reactive with other elements – Do not appear in nature alone only in compounds
    • Group 18-Noble Gases• Nonmetals• 8 valence electrons in outer level (full level) (except helium which has 2 valence electrons, which makes helium full) and very un-reactive – inert• Do not form compounds under normal conditions
    • Hydrogen• Nonmetal• 1 electron in outer level so it is set above the alkali metals and is reactive• Properties: even though above metal category, has properties of nonmetals• Most abundant element in universe, makes up stars
    • • Atomic number = Number of Protons• Electrons equal to the number of protons• Neutrons equal atomic mass (rounded) minus the protons• Protons do not change in a atom, neutrons can change, electrons can be shared or transferred (when bonds are made)