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UNIT 5 – Periodic Laws

UNIT 5 – Periodic Laws. THE PERIODIC CHART. H ISTORY. Dalton : grouped elements by their properties Berzelius : gave elements names and symbols ( important because he established order) Newlands law of the octaves 1 st and 8 th counted on his chart were similar

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UNIT 5 – Periodic Laws

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  1. UNIT 5 – Periodic Laws THE PERIODIC CHART

  2. HISTORY • Dalton: grouped elements by their properties • Berzelius: gave elements names and symbols ( important because he established order) Newlands law of the octaves 1st and 8th counted on his chart were similar Doberiener developed groups of 3’s called triads, had math rule mass of 1st plus mass of 3rd divided by 2 = mass of 2nd Meyer: graphed elements by masses

  3. Mendeleyev: University professor in Russia, he published the Periodic Chart of elements on March 9, 1869 similar to ours. He developed the groups and series with only 7 major “families”. • Ramsey: In the 1890’s the 8th family was discovered • Moseley: grouped chart by the order of atomic # instead of mass. • Joliet: produced the 1st synthetic element in 1936, Tc • IUPAC: A committee that take care of our present chart ( meet every other year in Paris )

  4. Parts • Families (8) named columns • Groups (18) numbered columns • Series / Periods (8) numbered rows

  5. FAMILY NAMES • ALKALI - NITROGEN • ALKALINE - CHALCOGEN • “NO NAME”(transition) - HALOGEN • CARBON - INERT (NOBLE)

  6. Regions of the Chart • Active Metals “s” first and second groups of elements • Transition “d” groups 3 – 12 metals • “p” elements of groups 13 – 18 metals / metalloids / nonmetals • Rare Earth “f” Rare natural metals and synthetic elements

  7. The Steps • Metals To the left of the steps (zig-zag) • Metalloids On / near the steps • Nonmetals To the right of the steps

  8. Periodic Properties 1. Atom Size • a) down - family or group increases , add new layers of electrons ( shells/energy levels) • b) to right - is smaller, protons have stronger pull Fr is the largest F is the smallest 2. Ion Size • a) Metals who lose electrons are called cations M+ M+ is smaller than M atom • b) Nonmetals gain electrons are called anions Nm- Nm- is larger than Nm atoms • 8th family normally does not form ions

  9. 3. Activity • a)Groups/families of metals are down more active • b) Groups/Families of Nm up is more active • c) Across ( period/series ) more active-------------- less------------ more active

  10. 4 Metallic Properties • increase as going down • increase at left

  11. 5 Ionization Energy (IE) • The Energy needed to remove one electron from an element 1st IE 2nd IE 3rd IE 4th IE Least Energy More E Somewhat more Most E • easy: this depends on the #of valence electrons Metals have a LOW IE • hard: on inner shells, once valence are gone Nonmetals have HIGH IE 6 Electron Affinity (EA) • the attraction of an element for its outer shell electron Metals have a LOW EA / Nonmetals have HIGH EA 7 Electronegativity (EN) • the energy exchange as a an atom gains one electron Metals have a LOW EN/ Nonmetals have HIGH EN Glitch: where a family or group doesn’t fit a pattern, the most common glitch is 13 group, but groups 2-3, 8, 10 and 15 sometimes break the rules

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