Unit 3 Notes: Periodic Law Dunton Honors Chem

Periodic Table Periods- left to right Groups- up & down, numbered 1-18 or 1A-7A, O & B’s Representative Elements- Group A Elements, Group 1, 2, & 13-18

7.1 The Periodic Table Mendeleev- Arranged by increasing atomic mass, left blank spaces, able to predict properties of missing elements b/c properties repeated Moseley- arranged in order of increasing atomic number, the one we use today Periodic Law- elements in increasing atomic number will have a periodic repetition of physical & chemical prop. Cannizzaro- standardized atomic masses on PT

 Using periodic table can find:  Element Symbol  Avg. Atomic Mass  Physical state of Atom  Group # & can infer properties  Electron configuration

3 Main Groups of Elements on PT Metals- o Left side of PT o 80% elements o Conduct electricity o Luster o Ductile o Malleable o Mostly solids w/ some exceptions o Group 1 Alkali metals o Group 2 Alkaline Earth Metals o Group B- Transition & Inner Transition Metals

 Nonmetals- o Right side of PT o Don’t conduct electricity o Aren’t ductile or malleable o Can be solids, liquids or gases o No luster, dull o 1 7- Halogens o 18 - Noble gases Metalloids- B, Si, Ge, As, Sb, Te, Po, At o Border Stair Step o Properties of metals & nonmetals o Used in solar cells & computer chips Semi conductor

7.5 Development of the Modern Periodic Table

 Trends:  Atomic Radius- ½ d between the nuclei of 2 like atoms  Group Trend: increase radius down group b/c add levels & increase shielding (distance & levels to nucleus)  Period Trend: decrease size as move l  r across period b/c more pull from nucleus

Atomic Radius Questions: Which has a large atomic radius: Li or Ne? Why? Which has a smaller atomic radius: Na or Cs? Why?

Periodic Trends  Shielding- when levels of electrons “block” the pull of the nucleus from the outer electrons  As you go across the periodic table (period), shielding does not change  As you go down a group, shielding increases b/c you have added a level

 Ionization Energy -(E I ) E to lose e- & become an ion  Group Trend: decrease as move down period b/c shielding  Period Trend: increase as move l  r b/c closer to nucleus

 Ionic size- radius of ion  Group Trend: increase as you go down a group b/c added a level  Group Trend:  Groups 1-13 lose e- so get smaller than atom  Groups gain e- so get bigger  Groups 14 & 18- don’t usually lose or gain e-

 Electronegativity- (EN) tendency of an atom to pull e- to itself when chemically bonded to another atom  Units of Paulings  Noble gases omitted b/c inert  F is most  Fr/Cs is least  Group : Further down a group lower EN  Period Trend: l  r increase EN

Electron Affinity; kJ/mol  The ability to pull electrons to itself; the energy change that occurs when an electron is added to a gaseous atom  Trend: As move l  r becomes increasingly negative (since they want to gain e-anyway)  No significant change as we move down a group b/c filling the same orbital  The more negative the number the more energy released= the more likely it its to happen  If the number is >0; takes too much energy to add and won’t be stable; ex.noble gases chart pg 237

Ch 7 Periodic Trends 1H1H 3 Li 11 Na 19 K 37 Rb 55 Cs 87 Fr 4 Be 12 Mg 20 Ca 38 Sr 56 Ba 88 Ra 21 Sc 39 Y 57 La 89 Ac 22 Ti 40 Zr 72 Hf 104 Rf 23 V 41 Nb 73 Ta 105 Db 42 Mo 74 W 106 Sg 25 Mn 43 Tc 75 Re 107 Bh 26 Fe 44 Ru 76 Os 108 Hs 27 Co 45 Rh 77 Ir 109 Mt 28 Ni 46 Pd 78 Pt 110 Uun 111 Uuu 30 Zn 48 Cd 80 Hg 8O8O 16 S 34 Se 52 Te 84 Po 7N7N 15 P 33 As 51 Sb 83 Bi 6C6C 14 Si 32 Ge 50 Sn 82 Pb 5B5B 13 Al 31 Ga 49 In 81 Tl 9F9F 17 Cl 35 Br 53 I 85 At 2 He 10 Ne 18 Ar 36 Kr 54 Xe 86 Rn 24 Cr 29 Cu 47 Ag 79 Au 112 Uub 114 Uuq 116 Uuh 118 Uuo Electronegativity decreases Ionization energy decreases Atomic radius increases Electronegativity increases Ionization energy increases Atomic radius decreases

7-6 Properties of the s-Block Elements  Diagonal Relationships – some period 2 elements behave more like the period 3 elements in the next group than what is expected based on their position.  Li behaves like Mg  B behaves like Si  Be behaves like Al

7-6: Properties of s-Block Elements  H is in group 1 because it has 1 valence electron  It has metallic and non metallic properties  Metal: loses an e -  Non-metal: gas, increase reactivity (like halogens) gains an e -

7-6: Properties of s-Block Elements  H is in group 1 because it has 1 valence electron  It has metallic and non metallic properties  Metal: loses an e -  Non-metal: gas, increase reactivity (like halogens) gains an e -

7-6: Properties of s-Block Elements  Alkali Metals: Group 1  “ashes of saltwort plant”  React with water to form alkaline solutions, lose 1 valence e- becoming a 1 + ion, soft metal, highly reactive, the best conductors of heat and electricity  So reactive that they must be stored under oil  Why are they so reactive? (think about their electron configurations and the octet rule)

7-6: Properties of s-Block Elements  Alkaline Earth Metals: Group 2  Shiny solids, harder than alkali metals, less reactive then alkali metals, lose 2 valence e- becoming a 2 + ion, good conductors of heat and electricity, react with water  Why are they less reactive than the alkali metals?

7-6: Properties of p-Block Elements  Group 13: The “Boron” Group  Boron is a metalloid, the rest are metals  B, Al, Ga, In lose 3 valence e -  Tl loses 1p valence e - (Ga and In can too)  Group 14: The “Carbon” Group  C is a nonmetal, Si and Ge are metalloids, Sn and Pb are metals

7-7: Properties of p-Block Elements  Mineral: found in nature as solid crystals  Ore:material that can be removed at a reasonable cost  Alloy- mixture containing a metal  Allotrope: forms of an element in the same physical state – solid, liquid, or gas – that have different structures and properties  Diamond, graphite, and coal

7-7: Properties of p-Block Elements  Group 15: The “Nitrogen” Group  N and P are nonmetals and gain 3 e - to become a 3 - charged ion  As and Sb are metalloids  Bi is a metal and loses 3 e - to become a 3 + charged ion

7.7  Group 16: The “Oxygen” Group  6 valence e -, gain 2 e - to become ions with a 2 - charge  O, S, and Se are nonmetals  Te and Po are metalloids  Group 17 Halogens: most reactive nonmetals

8.1  Atom- same number of protons and electrons  Valence electron- outer shell electron  Valence shell- outer shell of electrons  Ion- Numbers of protons & electrons are not equal  Cation- loses electrons, positive charge  Anion- gains electrons; negative charge

Forming Chemical Bonds  Chemical Bond: a force holding 2 atoms together  Some atoms lose/gain e - to make ions (+/- attract)  Attraction between ions (+-); metal and nonmetal= ionic bonding  Sharing electrons; nonmetals = covalent bonding  Electrons are free to move throughout 3-D structure=metallic bonding

 Octet rule- atoms will gain, lose or share e- to get 8 e- on their outer shell (called psuedo-noble gas configuration)  Elements do which ever is easiest  Na 1s 2 2s 2 2p 6 3s 1  Easier to lose 1 than to gain 7  Na + 1s 2 2s 2 2p 6  Cl 1s 2 2s 2 2p 6 3s 2 3p 5  Easier to gain 1 than to lose 7  Cl - 1s 2 2s 2 2p 6 3s 2 3p 6

How to tell:  Look at valence e -  Ions are more stable than neutral atoms  Positive ions (cation)  It takes energy to pull an e - away.  Reactivity of metals is based on the ease of losing valence e -

 Metals (cation) want to lose until they have a full s 2 p 6  Group 1 – Na 1s 2 2s 2 2p 6 3s 1 loses one e - to be 1s 2 2s 2 2p 6 now it has 11 p + and 10 e - (1 + charge)  Group 2 – lose 2 e - to hold a 2 + charge  Group 13 – lose 3 e - to hold a 3 + charge  Transition metals – most are 2 + some are

 Negative ions (anion)  Group 15 – 1s 2 2s 2 2p 3 gain 3  1s 2 2s 2 2p 6 so 3 - charge  Group 16 – 1s 2 2s 2 2p 4 gain 2  1s 2 2s 2 2p 6 so 2 - charge  Group 17 – 1s 2 2s 2 2p 5 gain 1  1s 2 2s 2 2p 6 so 1 - charge  Notice NO ion for Group 18 because they are an s 2 p 6 Inert (won’t react)