Mr. Matthew Totaro Legacy High School Honors Chemistry The Periodic Table

Döbereiner’s Triads Name Atomic Mass Name Atomic Mass Name Atomic Mass Calcium 40 Barium 137 Average 88.5 Strontium 87.6 Chlorine 35.5 Iodine 127 Average 81.3 Bromine 79.9 Sulfur 32 Tellurium Average 79.8 Selenium 79.2 Johann Döbereiner ~1817 Döbereiner discovered groups of three related elements which he termed a triad.

Newlands Law of Octaves 1 Li Na K John Newlands ~ Be Mg 3 B Al 4 C Si 5NP5NP 6OS6OS 7 F Cl

4 Dmitri Mendeleev Ordered elements by atomic mass. Saw a repeating pattern of properties. Periodic law —When the elements are arranged in order of increasing relative mass, certain sets of properties recur periodically. Used pattern to predict properties of undiscovered elements. Where atomic mass order did not fit other properties, he reordered by other properties. Te & I

Mendeleev’s Periodic Table 5

Mendeleev's Predictions 6

Periodicity When one looks at the properties of elements, one notices a repeating pattern of characteristics & reactivities. Periodic = repeating 7

Periodicity = Metal = Metalloid = Nonmetal

9 Metals Solids at room temperature, except Hg. Reflective surface = Luster. Shiny Conduct heat. Conduct electricity. Malleable. Can be shaped. Ductile. Drawn or pulled into wires. About 75% of the elements are metals. Lower left on the table.

10 Nonmetals Found in all 3 states. Poor conductors of heat. Poor conductors of electricity. Solids are brittle. Upper right on the table. Except H. Nonmetallic Bromine

11 Metalloids Show some properties of metals and some of nonmetals. Also known as semiconductors. Properties of Silicon: Shiny Conducts electricity Does not conduct heat well Brittle

The Modern Periodic Table Determined the atomic numbers of elements from their X-ray spectra (1914) Arranged elements by increasing atomic number Killed in WW I at age 28 (Battle of Gallipoli in Turkey ) Henry Moseley 12

13 The Modern Periodic Table Elements are arranged from left to right in order of increasing atomic number There are 18 vertical columns called Families There are 7 horizontal rows called Periods.

The Modern Periodic Table

Long Form of the Periodic Table

16 The Modern Periodic Table Main group = representative elements = “A” groups Transition elements = “B” groups all metals Bottom rows = inner transition elements = rare earth elements metals really belong in Period 6 & 7

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Families of the Elements

20 = Alkali metals = Alkali earth metals = Noble gases = Halogens = Lanthanides = Actinides = Transition metals

lithium sodium potassium rubidium cesium 21 Important Groups – Alkali Metals Group IA (1)= Alkali Metals Hydrogen usually placed here, though it doesn’t really belong Soft, low melting points, low density Flame tests: Li = red, Na = yellow, K = violet Very reactive, never find uncombined in nature

22 Important Groups - Alkali Earth Metals Group IIA (2)= Alkali Earth Metals harder, higher melting, and denser than alkali metals Mg alloys used as structural materials flame tests: Ca = red, Sr = red, Ba = yellow-green reactive, but less than corresponding alkali metal magnesium calcium beryllium strontium barium

23 Important Groups – Halogens Group VIIA (17) = halogens Nonmetals Only family with solids, liquids, and gases All diatomic Very reactive bromine iodine chlorine fluorine astatine

24 Important Groups - Noble Gases Group VIIIA (18) = Noble Gases all gases at room temperature very low melting and boiling points very unreactive, practically inert very hard to remove electron from or give an electron to helium neon argon krypton xenon

25 Important Groups - Hydrogen Nonmetal Colorless, diatomic gas very low melting point and density Makes up over 90% of all atoms in the universe Excited Hydrogen Gas

26 States of the Elements (at STP) Orange = Solid Red = Liquid Purple = Gas

The Modern Periodic Table

28 Valence Electrons The electrons in all the sublevels with the highest principal energy levels are called the valence electrons. Electrons in lower energy levels are called core electrons. Chemists have observed that one of the most important factors in the way an atom behaves, both chemically and physically, is the number of valence electrons.

29 Valence Electrons and Core Electrons

Valence vs. Core Electrons in Carbon 30 C = 6 e - =1s 2 2s 2 2p 2

31 Valence Electrons, Continued Rb = 37 electrons = 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 1 The highest principal energy level of Rb that contains electrons is the 5 th, therefore, Rb has 1 valence electron and 36 core electrons. Kr = 36 electrons = 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 The highest principal energy level of Kr that contains electrons is the 4 th, therefore, Kr has 8 valence electrons and 28 core electrons.

32 Electron Configuration from the Periodic Table P = [Ne]3s 2 3p 3 P has 5 valence electrons. 3p33p3 P Ne A 2A 3A4A5A6A7A 8A 3s23s2

33 Practice—Determine the Number of Valence Electrons in an Arsenic, As, Atom (use the Noble Gas shortcut).

34 Electron Configuration from the Periodic Table, Continued As = [Ar]4s 2 3d 10 4p 3 As has 5 valence electrons. As A 2A 3A4A5A6A7A 8A 4s24s2 Ar 3d 10 4p34p3

35 Energy 1s 7s 2s 2p 3s 3p 3d 6s 6p 6d 4s 4p 4d 4f 5s 5p 5d 5f

36 s1s1 s2s2 d 1 d 2 d 3 d 4 d 5 d 6 d 7 d 8 d 9 d 10 p 1 p 2 p 3 p 4 p 5 s2s2 p6p6 f 1 f 2 f 3 f 4 f 5 f 6 f 7 f 8 f 9 f 10 f 11 f 12 f 13 f Sublevels and the Periodic Table

37 Element Blocks on the Periodic Table Blocks of Elements

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39 Electron Configuration and the Periodic Table Elements in the same column have similar chemical and physical properties because they have the same number of valence electrons. The number of valence electrons for the main group elements is the same as the group number.

Electron Configuration of The Alkali Metals 40

41 Electron Configuration of The Halogens

Electron Configuration of The Noble Gases 42

Periodic Trends in the Properties of the Elements

Reactivity For the metals, as you move down a family, reactivity goes up. As you move across a period, reactivity goes down. Brainiac’s Video For the nonmetals, as you move down a family, reactivity goes down. As you move across a period, reactivity goes up. Except for the Noble Gases!!!! 44

45 Trends in Atomic Size Either volume or radius. Treat atom as a hard marble. As you traverse down a column on the periodic table, the size of the atom increases. Valence shell farther from nucleus. Effective nuclear charge fairly close. As you traverse left to right across a period, the size of the atom decreases. Adding electrons to same valence shell. Effective nuclear charge increases. Valence shell held closer.

46 Trends in Atomic Size, Continued

47 4 p + 2e - 12 p + 2e - 8e - 2e - Be (4p + and 4e - ) Group IIA Mg (12p + and 12e - ) Ca (20p + and 20e - ) 16 p + 2e - 8e - 2e - 8e -

48 Li (3p + and 3e - ) Period 2 Be (4p + and 4e - )B (5p + and 5e - ) 6 p + 2e - 4e - C (6p + and 6e - ) 8 p + 2e - 6e - O (8p + and 8e - ) 10 p + 2e - 8e - Ne (10p + and 10e - ) 2e - 1e - 3 p + 2e - 4 p + 2e - 3e - 5 p +

49 Choose the Larger Atom in Each Pair C or O Li or K C or Al Se or I?

50 Practice—Choose the Larger Atom in Each Pair. 1.N or F 2.C or Ge 3.N or Al 4.Al or Ge

51 1. N or F 2. C or Ge 3. N or Al 4. Al or Ge? opposing trends 1. N or F 2. C or Ge, Ge is further down 1. N or F 2. C or Ge 3. N or Al, Al is further down & left 1. N or F, N is further left Practice—Choose the Larger Atom in Each Pair, Continued.

Trends in Ionic Radius 52 Ions in same group have same charge Ion size increases down the column higher valence level, larger size Cations smaller than neutral atoms; anions larger than neutral atoms Cations smaller than anions Larger positive charge = smaller cation Larger negative charge = larger anion

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Example: Choose the larger of each pair S or S 2 − Ca or Ca 2+ Br − or Kr 55

56 Ionization Energy Minimum energy needed to remove an electron from an atom. Gas state. Valence electrons are the easiest to remove. M(g) + 1st IE  M 1+ (g) + 1 e - M +1 (g) + 2nd IE  M 2+ (g) + 1 e -  First ionization energy = energy to remove electron from neutral atom; 2nd IE = energy to remove from +1 ion; etc.

57 Trends in Ionization Energy As you move down a family, the IE gets smaller. Valence electron farther from nucleus. As you move left to right across a period, the IE gets larger.

58 Trends in Ionization Energy, Continued

59 1. Al or S 2. As or Sb, As is farther up 1. Al or S 2. As or Sb 3. N or Si, N is further up and right 1. Al or S 2. As or Sb 3. N or Si 4. O or Cl, opposing trends Example—Choose the Atom in Each Pair with the Higher First Ionization Energy 1. Al or S, S is further Right

60 Practice—Choose the Atom with the Highest Ionization Energy in Each Pair 1.Mg or P 2.Cl or Br 3.Se or Sb 4.P or Se

61 Practice—Choose the Atom with the Highest Ionization Energy in Each Pair, Continued 1.Mg or P 2.Cl or Br 3.Se or Sb 4.P or Se ?

62 Metallic Character How well an element’s properties match the general properties of a metal. In general, metals are found on the left of the periodic table and nonmetals on the right. As you go left to right across the period, the elements become less metallic. As you go down a column, the elements become more metallic

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64 1. Sn or Te 2. P or Sb, Sb is further down 1. Sn or Te 2. P or Sb 3. Ge or In, In is further down & left 1. Sn or Te 2. P or Sb 3. Ge or In 4. S or Br? opposing trends 1. Sn or Te, Sn is further left Example—Choose the More Metallic Element in Each Pair

65 Practice—Choose the More Metallic Element in Each Pair 1.Na or Al 2.Si or Sn 3.Br or Te 4.Se or I

66 Practice—Choose the More Metallic Element in Each Pair, Continued 1.Na or Al 2.Si or Sn 3.Br or Te 4.Se or I ?

Electronegativity The ability of an atom to attract valence electrons to itself is called electronegativity Increases across period (left to right) and Decreases down group (top to bottom) fluorine is the most electronegative element francium is the least electronegative element noble gas atoms are not assigned values opposite of atomic size trend 67

Electronegativity Scale 68