The Periodic Table & Periodic Law Chapter 6 Chemistry X
History of the Periodic Table John Newlands Law of octaves Lothar Meyer Dmitri Mendeleev organized according to he saw repeating (periodic) trends Predicted the existence of Ga,, Sc, Ge LATER - Newly discovered elements did fit Mendeleev s s trends Henry Mosely organized according to
Periodic Law As atomic # increases, there is a periodic repetition of chemical and physical properties Groups families columns Periods series rows
Periodic Table Label Metals/nonmetal/metalloids Label important group names Octet Rule: Write the Lewis Dot Structure for each element in the 3 rd period. Write the Lewis Dot Structure for the ion formed by each element in the 3 rd period.
Periodic Table 1) Draw the Electron Dot Structures (Lewis Dot Structures) for each of the following 2) What group # is this element from? 3) Indicate the number of valence electrons in each group. 4) Indicate the likely charge(s) for atoms in that group. He Na Mg Al Si P S Cl Ar group # # valence e- charge:
Periodic Table Make a line showing where the metalloids are located. Write the charges for ions formed by each group. Metals form (+) ions Nonmetals form (-)( ) ions
Alkali Metals Highly reactive React violently with water to produce H 2 gas very soft Francium is the most reactive
Alkaline Earth Metals Fairly reactive (not as much as group 1) React somewhat with water
Halogens highly reactive exist as diatomic molecules Fluorine is the most reactive
Noble Gases very unreactive inert Very stable He, Ne, Ar have never reacted
Transition Metals have 2 valence electrons can have multiple ion charges many compounds formed by these metals are colored
Inner Transition Metals or Rare Earth Elements Lanthanides & Actinides low abundance in nature actinides are synthetic & radioactive
What about Hydrogen? Acts like an alkali metal. By losing an electron to be like a noble gas Acts like a halogen by gaining an electron to be like a noble gas
Element Classification Metals Metalloids Nonmetals Conductor 1) 1) Semiconductors 1) Heat & electricity 2) malleable (exhibit 2) 3) ductile metallic/ nonmetallic 3) 4) lustrous properties) 4) 5) Most react w/acid Non-conductor brittle dull Solid/liquid/gas 6) Most react w/cucl 2
Metals Element Classification of elements Form ions All @ room temp. except Nonmetals @ room temp. form ions Metalloids metalloids
Element Classification s-block metals are softer and not as dense as the p-block and d-block metals d-block are harder and denser than p-block and s-block melting/boiling points for metals as you go down columns, thus intermolecular forces as you go down columns. melting/boiling points for nonmetals as you go down columns, thus intermolecular forces as you go down columns. Metal reactivity increases columns and to the. Nonmetal reactivity increases columns and to the.
Periodic Trends Shielding/Z eff shielding effect the outer electrons can be shielded from the nuclear charge by the inner/core e-e Z eff Z effective the effective charge of the nucleus Z eff =
Periodic Trends Atomic Radii Atomic Radii one-half the distance between the nuclei of two identical atoms bonded together down columns across rows
Periodic Trends Ionization Energy Ionization Energy the energy require to remove an e-e Ion an atom that has a positive or negative charge Cation Anion - 1st IE the energy required to remove the first mole of e-e 2nd IE the energy required to remove
Periodic Trends Ionization Energy Element IE 1 IE 2 IE 3 IE 4 Li 124 1,748 2,815 --- Be 215 418 3,532 5,004 B 191 577 872 5,964
Periodic Trends Successive Ionization Energies It gets to remove successive electrons. There is a big jump in the amount of energy needed when
Periodic Trends Ionization Energy The following are Ionization energies for Na, Mg, and Al. Identify the set of IE s s that belong to each element. Element IE 1 IE 2 IE 3 IE 4 A 118 1,091 1,653 --- B 138 434 656 2,767 C 175 345 1,839 2,526 KEY: # electrons lost easily can tell us 1) 2)
Periodic Trends Successive Ionization Energies IE generally across periods IE generally down columns
Periodic Trends Ionization Energy Trend Diagram
Octet Rule Periodic Trends Ionization Energy
Periodic Trends Electron Affinity Electron Affinity the energy change that occurs when an e-e is acquired by a neutral atom
Periodic Trends Electron Affinity The trend is the same as for I.E., but not as regular Note: It s s always to add a second electron
Periodic Trends Electronegativity Electronegativity a measure of the ability of an atom to attract e-e Tends to across periods Tends to down columns the most electronegative atom is.
Ionic Radii Periodic Trends Ionic Radii Cation Anion See next slide for ionic radii diagram.
Ionic Radii - diagram
isoelectric - Periodic Trends Ionic Radii
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Trend Summary Trend Summary Fill-in in table Z eff Shielding effect Ionization energy Electronegativity e- affinity Atomic radii Zeff Shielding effect Ionization energy Electronegativity e- affinity Atomic radii
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