THE PERIODIC TABLE Objective: Explain the Use of Chemical and Physical Properties in the Historical Development of the Periodic Table
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THE PERIODIC TABLE Objective: Explain the use of chemical and physical properties in the historical development of the Periodic Table. ■ Antoine Lavoisier: In the 1700’s complied a list of all know elements (33) organized into 4 categories. – Gases (light, heat, inflammable air, etc.) – Metals (antimony, silver, arsenic, bismuth, zinc, etc.) – Nonmetals (sulfur, phosphorus, pure charcoal, etc.) – Earths (chalk, clay, siliceous earth, etc.) ■ John Newlands: In 1864 he noticed that when the elements were arrange in order of increasing ATOMIC MASS that the properties REPEATED EVERY 8 ELEMENTS. – This pattern is called PERIODIC. – Called this the Law of Octaves. – Not accepted because did not work for all elements and “octave” sounded “unscientific.” Dmitri Mendeleev: 1869 Father of The Periodic Table ■ Also noticed that when the elements were arranged by atomic mass that there was a Periodic Pattern in their properties. ■ His table had vertical rows and horizontal columns. ■ The Columns had SIMILAR PROPERTIES. ■ Left BLANK SPACES for undiscovered elements. ■ Predicted the properties for: – scandium – gallium – germanium ■ Lothar Meyers demonstrated the same connection but Mendeleev was FIRST. Henry Moseley (1887 – 1915) ■ Problems with Mendeleev’s table: ■ MODERN PERIODIC TABLE ■ Vertical Columns: – As new elements were discovered did not fit – Groups or Families pattern. – 18 groups ■ Henry Moseley discovered that each element had a ■ Horizontal Rows: – Periods UNIQUE NUMBER OF PROTONS. – 7 periods ■ This is the ATOMIC NUMBER. ■ Representative Elements: – groups 1, 2, 13-18 ■ In 1913 he proposed that the Period Table be ■ Transition Elements: organized by Atomic Number which gave a CLEAR – groups 3-12 Period Pattern. – Inner Transition Metals ■ Also classified as: ■ PERIODIC LAW: There is a periodic repetition of – metals chemical and physical properties of the elements – nonmetals when they arranged by increasing ATOMIC NUMBER. – metalloids The Modern Periodic Table ■ Objective: Use the Periodic Table to identify and explain the properties of chemical families including alkali metals, alkaline earth metals, halogens, noble gases, and transition metals. Electron Arrangements Alkali Metals ■ Family 1 ■ Most active of all the metals ■ One valance electron in outer most energy level. (ns1: Li – 1s22s1, Na – 1s22s22p63s1) ■ Lose the one valance electron when forming chemical bonds. ■ Form +1 ions. ■ All atoms “want to have an octet of valance electron so they will gain lose or share electrons to get to this “magic number.” Alkaline Earth Metals ■ Family 2. ■ Second most active of the metals. ■ Two valance electrons (ns2: Be – 1s22s2, Mg – 1s22s22p63s2) ■ Lose 2 valance electrons when forming chemical bonds. ■ Form +2 ions. Transition Metals ■ Group 3 – Group 12 ■ Less active than alkali or alkaline earth metals. ■ One or two valance electrons. All transition metals have ns1 or ns2 valance electron structures. ■ They have (n-1)d1 – (n-1)d10. ■ They have oxidations (ion charges) of +1 through +7. ■ Transition metals do not obtain octets because they have “d” electrons involved in bonding. Boron Family ■ Family 13 ■ Boron – metalloid ■ Aluminum and rest are metals. ■ 3 valance electrons. ■ ns2np1 ■ +3 ion charge Carbon Family ■ Family 14 ■ Carbon – nonmetal ■ Silicon and germanium are metalloids. ■ Tin and lead are metals. ■ 4 valance electrons. ■ ns2np2 ■ Carbon and silicon can be +4 or -4 or it can share electrons to form bonds. ■ Tin and lead can be +2 or +4. Nitrogen Family ■ Family 15 ■ Nitrogen and phosphorus are nonmetals. ■ Arsenic and antimony are metalloids. ■ Bismuth is a metal. ■ 5 valance electrons. ■ ns2np3 ■ Nitrogen and phosphorus are usually - 3. ■ Bismuth and antimony are +3 or +5. Oxygen Family ■ Family 16 ■ Oxygen, sulfur and selenium are nonmetals. ■ Tellurium and polonium are metalloids. ■ 6 valance electrons. ■ ns2np4 ■ Oxygen and sulfur are usually -2. Halogens ■ Family 17. ■ Most active of the nonmetals. ■ 7 valance electrons (ns2np5: F – 1s22s22p5, Cl – 1s22s22p63s23p5) ■ Gain 1 electron to obtain octet. ■ Form -1 ions. ■ Halogens is Greek for salt former; they form salts when reacting with metals. Noble Gases (Inert Gases) ■ Family 18. ■ Most inactive of all elements. ■ Do not normally form compounds. ■ 8 valance electrons (ns2np6: Ne – 1s22s22p6, Ar – 1s22s22p63s23p6) ■ A perfect octet of electrons so they do not gain or lose electrons to form compounds. ■ Helium is only 1s2, but it still does not form compounds because the 1st energy level is filled with only 2 electrons. Periodic Trends Objective: Use the Periodic Table Atomic Radius: One half the to identify and explain periodic distance between 2 adjacent trends, including atomic and atoms. ionic radii, electronegativity, and ionization energy. Ionization Energy Electronegativity Energy required to remove The relativity of an atom to an electron from an atom attract electrons in a chemical bond. Periodic Trends Ionization Energy Graph Atomic # 1 2 3 4 1 H 1,312 2 He 2,372 5,251 3 Li 520.3 7,298 11,815 4 Be 899.5 1,757 14,849 21,007 5 B 800.7 2,427 3,660 25,026 6 C 1,086 2,353 4,621 6,223 7 N 1,402 2,856 7,475 9,445 8 O 1,314 3,388 5,301 7,469 9 F 1,681 3,374 6,051 8,408 10 Ne 2,081 3,952 6,122 9,370 11 Na 495.9 4,563 6,913 9,544 12 Mg 737.8 1,451 7,733 10,541 13 Al 577.6 1,817 2,745 11,578 14 Si 786.5 1,577 3,232 4,356 15 P 1,012 1,903 2,912 4,957 16 S 999.6 2,251 3,361 4,564 17 Cl 1,251 2,297 3,822 5,158 18 Ar 1,521 2,666 3,931 5,771 19 K 418.9 3,051 4,412 5,877 20 Ca 589.8 1,145 4,912 6,474 The Periodic Law ■ Date: October 23 / October 24 ■ Partners: ■ Problem: Can the properties of elements on the periodic table be predicted by measuring the same properties for other elements in the same family? ■ Hypothesis: Procedures ■ 1. Use a spot plate to determine the solubilities of the alkaline earth metals. ■ 2. React: magnesium nitrate, calcium nitrate, strontium nitrate, and barium nitrate; ■ with: ammonium oxalate, sulfuric acid, sodium carbonate, and potassium chromate. Procedures ■ 3. Determine the mass and volume of elements in the carbon family: silicon, tin, and lead. ■ 4. Calculate the densities for each element. Results: Data Table -2 -2 -2 -2 C2O4 SO4 CO3 CrO4 Mg+2 Ca+2 Sr+2 Ba+2 Results: Data Table mass volume density (g) (cm3) (g/cm3) silicon tin lead Results: Graph ■ Create a graph representing the density of elements in family 14. ■ Density will be the dependent variable and atomic number will be the independent variable. ■ Use the graph to predict the density of germanium (atomic number 32) Results: Calculation ■ Calculate the error for the density of germanium. ■ Experimental Error = ■ | Actual density – Experimental Density | X 100 ■ Actual Density ■ Actual Density of Ge = 5.32 g/cm3 Conclusion ■ Conclusion: ■ Restate problem and hypothesis. ■ What is the pattern for change in solubility for the alkaline earth metals? ■ Predict the solubility of beryllium and radium. ■ What is the pattern for change in density for family 14? ■ Predict the density of germanium..