Unit 3 Notes: Periodic Law

Dunton

Honors Chem

Periodic Table

Periods- left to rightGroups- up & down, numbered 1-18 or 1A-7A, O

& B’sRepresentative Elements- Group A Elements, Group 1, 2, & 13-18

7.1 The Periodic TableMendeleev- 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 todayPeriodic 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 SymbolAvg. Atomic MassPhysical state of AtomGroup # & can infer properties

Electron configuration

3 Main Groups of Elements on PT      Metals-

o        Left side of PTo        80% elementso        Conduct electricityo        Lustero        Ductileo        Malleableo        Mostly solids w/ some exceptionso        Group 1 Alkali metalso        Group 2 Alkaline Earth Metalso Group B- Transition & Inner Transition Metals

         Nonmetals-o        Right side of PTo        Don’t conduct electricityo        Aren’t ductile or malleableo        Can be solids, liquids or gaseso        No luster, dullo        17- Halogenso        18- Noble gases Metalloids- B, Si, Ge, As, Sb, Te, Po, Ato        Border Stair Stepo        Properties of metals & nonmetalso        Used in solar cells & computer chips

Semi conductor

7.5 Development of the Modern Periodic Table

1IA

18VIIIA

12

IIA13

IIIA14

IVA15VA

16VIA

17VIIA

2

33

IIIB4

IVB5

VB6

VIB7

VIIB8 9

VIIIB10 11

IB12IIB

4

5

6

7

MetalsMetalsNonmetalsNonmetals

7.1-7.4 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 lr 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 -(EI) E to lose e- & become an ion

   Group Trend: decrease as move down period b/c shielding

  Period Trend: increase as move lr 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 15-17 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: lr 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 lr 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 Trends1H

3Li

11Na

19K

37Rb

55Cs

87Fr

4Be

12Mg

20Ca

38Sr

56Ba

88Ra

21Sc

39Y

57La

89Ac

22Ti

40Zr

72Hf

104Rf

23V

41Nb

73Ta

105Db

42Mo

74W

106Sg

25Mn

43Tc

75Re

107Bh

26Fe

44Ru

76Os

108Hs

27Co

45Rh

77Ir

109Mt

28Ni

46Pd

78Pt

110Uun

111Uuu

30Zn

48Cd

80Hg

8O

16S

34Se

52Te

84Po

7N

15P

33As

51Sb

83Bi

6C

14Si

32Ge

50Sn

82Pb

5B

13Al

31Ga

49In

81Tl

9F

17Cl

35Br

53I

85At

2He

10Ne

18Ar

36Kr

54Xe

86Rn

24Cr

29Cu

47Ag

79Au

112Uub

114Uuq

116Uuh

118Uuo

Ele

ctro

nega

tivity

dec

reas

esIo

niza

tion

ener

gy d

ecre

ases

Ato

mic

rad

ius

incr

ease

s

Electronegativity increasesIonization energy increasesAtomic 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 MgB behaves like SiBe behaves like Al

7-6: Properties of s-Block Elements

H is in group 1 because it has 1 valence electronIt 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 electronIt 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 oilWhy are they so reactive? (think about their electron

configurations and the octet rule)

7-6: Properties of s-Block Elements

Alkaline Earth Metals: Group 2Shiny 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 waterWhy are they less reactive than the alkali

metals?

7-6: Properties of p-Block Elements

Group 13: The “Boron” GroupBoron 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 ElementsMineral: found in nature as solid crystalsOre: material that can be removed at a

reasonable costAlloy- mixture containing a metalAllotrope: forms of an element in the same

physical state – solid, liquid, or gas – that have different structures and propertiesDiamond, graphite, and coal

7-7: Properties of p-Block ElementsGroup 15: The “Nitrogen” Group

N and P are nonmetals and gain 3 e- to become a 3- charged ion

As and Sb are metalloidsBi is a metal and loses 3 e- to become a 3+

charged ion

7.7Group 16: The “Oxygen” Group

6 valence e-, gain 2 e- to become ions with a 2-

chargeO, S, and Se are nonmetalsTe 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 BondsChemical Bond: a force holding 2 atoms

togetherSome atoms lose/gain e- to make ions (+/-

attract)Attraction between ions (+-); metal and

nonmetal= ionic bondingSharing electrons; nonmetals = covalent

bondingElectrons 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 1s22s22p63s1

Easier to lose 1 than to gain 7 Na+ 1s22s22p6

Cl 1s22s22p63s23p5

Easier to gain 1 than to lose 7 Cl- 1s22s22p63s23p6

How to tell:

Look at valence e-

Ions are more stable than neutral atomsPositive 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 s2p6

Group 1 – Na 1s22s22p63s1 loses one e- to be 1s22s22p6 now it has 11 p+ and 10 e- (1+ charge)

Group 2 – lose 2 e- to hold a 2+ chargeGroup 13 – lose 3 e- to hold a 3+ chargeTransition metals – most are 2+ some are

3+

+ +

Negative ions (anion)Group 15 – 1s22s22p3 gain 3 1s22s22p6 so 3- chargeGroup 16 – 1s22s22p4 gain 2 1s22s22p6 so 2- chargeGroup 17 – 1s22s22p5 gain 1 1s22s22p6 so 1- charge

Notice NO ion for Group 18 because they are an s2p6 Inert (won’t react)