Chapter 6Chapter 6The Periodic TableThe Periodic Table

p. 154p. 154

The Elements by Tom Lehrer

Organizing the Elements Chemists used elements properties

to sort into groups. 1829 - J. W. Dobereiner

triads – groups of 3 w/ similar properties One element in triad

had properties intermediate

of other 2 elements Cl, Br, and I look different….

similar chemically

Mendeleev’s Periodic Table 1800s, about 70 elements known 1869 - Dmitri Mendeleev – Russian

chemist & teacher Arranged elements by atomic mass

Mendeleev’s Periodic Table Blank spaces

undiscovered elementsPredicted properties

predictions very accurate Problems w/ order

Te to I atomic mass decreasesI belongs w/ Br & ClMendeleev broke rule – put Te before I

A better arrangement1913, Henry Moseley

British physicistDetermined atomic #’sModern PT arranged

by atomic #

The Elements by Tom Lehrer

Periodic Law Elements arranged by increasing

atomic #, periodic repetition of properties present

Horizontal rows = periods7 periods

Vertical column = group (family)Similar propertiesIUPAC labels (1-18)

U.S. system (# & letter…i.e. IA, IIA)

Areas of periodic table 3 classes of elements:

1) Metals: electrical conductors, lustrous, ductile, malleable

2) Nonmetals: generally brittle/non-lustrous, poor conductors of heat and electricity

Some gases (O, N, Cl) some brittle solids (B, S) fuming red liquid (Br)

3) Metalloids: border the line-2 sidesProperties are intermediate between

metals and nonmetals

Section 6.2Classifying the Elements

p. 161

Groups of elementsGroups of elements - family names- family names

Group IA – alkali metalsForms “base” (or alkali) when reacting

w/ H2O (not just dissolved!)

Group 2A – alkaline earth metalsAlso form bases with H2O; don’t

dissolve well, hence “earth metals”Group 7A – halogens

Greek hals (salt) & genesis (to be born)

Electron Configurations in Groups

sorted based on e- configs:

1) Noble gases2) Representative elements

3) Transition metals

4) Inner transition metals

Let’s now take a closer look at these.

Electron Configurations in Groups

1)1) Noble gasesNoble gases in Group 8A (also called Group 18)

very stable = don’t react e- configuration

full full outer s & p sublevels

Electron Configurations in Groups

2)2) Representative ElementsRepresentative Elements Groups 1A - 7A

Properties vary “Represent” all elements s & p sublevels of highest PEL NOT NOT

filledfilled Group # = valence e-’s

Electron Configurations in Groups

3)3) Transition metalsTransition metals in “B” columns outer s sublevel fulls sublevel full Start filling “d” sublevel “Transition” btwn metals &

nonmetals

Electron Configurations in Groups

4)4) Inner Transition MetalsInner Transition Metals below PT, 2 horizontal rows

outer s sublevel full Start filling “f” sublevel

1A

2A 3A 4A 5A 6A7A

8A Elements 1A-7A groups called

representative elements

outer s or p filling

The group B called transition elements

These are called the inner transition elements, and they belong here

Group 1A called alkali metals (but NOT H)

Group 2A called alkaline earth metals

H

Group 8A are noble gases Group 7A called halogens

Periodic table rap

Let’s take a quick break……

1s1

1s22s1

1s22s22p63s1

1s22s22p63s23p64s1

1s22s22p63s23p64s23d104p65s1

1s22s22p63s23p64s23d104p65s24d10

5p66s1

1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s1

H1

Li3

Na11

K19

Rb37

Cs55

Fr87

Do you notice any similarity in these configurations of the alkali metals?

He2

Ne10

Ar18

Kr36

Xe54

Rn86

1s2

1s22s22p6

1s22s22p63s23p6

1s22s22p63s23p64s23d104p6

1s22s22p63s23p64s23d104p65s24d105p6

1s22s22p63s23p64s23d104p65s24d10

5p66s24f145d106p6

Do you notice any similarity in the configurations of the noble gases?

Elements in the s - blocks

Alkali metals end in s1

Alkaline earth metals end in s2

should include He, but…properties of noble gases

full outer EL group 8A

s2s1

He

Transition Metals - d block

d1 d2 d3s1

d5 d5 d6 d7 d8s1

d10 d10

Note the change in configuration.

The P-blockp1 p2 p3 p4 p5 p6

F - block

Called “inner transition elements”

f1 f5f2 f3 f4

f6 f7 f8 f9 f10 f11 f12 f14

f13

Each period # = energy level for s & p orbitals.

1

2

3

4

5

6

7

Period Number

“d” orbitals fill up in levels 1 less than period # first “d” is 3d found in period 4.

1

2

3

4

5

6

7

3d

4d4d5d5d

f orbitals start filling at 4f….2 less than period #

1

2

3

4

5

6

7 4f4f

5f5f

Demo p. 165Demo p. 165

Trends in Trends in Atomic SizeAtomic Size

Atomic Radius - half distance btwn 2 nuclei of identical atoms

Increases top-bottomDecreases L-Rpicometers

10-12 m… 1 trillionth

RadiusRadius

Section 6.3 Periodic TrendsSection 6.3 Periodic Trendsp. 170

ALLALL PT Trends Influenced by 3 factors:

1. Energy LevelEnergy LevelHigher energy levels further from

nucleus

2. Charge on nucleusCharge on nucleus (# protons)More + charge pulls e-’s in closer

3. Shielding effectShielding effect

#1. Atomic Size - Group trends Going down a

group, atoms gain another PEL (floor)atoms get…..

HLi

Na

K

Rb

bbiigg

gg

eerr

#1. Atomic Size - Period Trends L to R across period:

More p+ in nucleusMore e-’s occupy same energy level

stronger nuclear charge Pulls e- cloud closer to nucleus

atoms get….

Na Mg Al Si P S Cl Ar

Here is an animation to explain the trend.

S m a l l e r

Trends of Atomic Radius

increases

decreases

increases

Ions p. 172p. 172 Some compounds composed of

“ions”Ion - atom (or group of atoms) w/ + or -

charge

formed when e- transferred btwn atoms

Cation (loses e-’s…+ ion)Anion (gains e-’s… - ion)

Cation FormationCation Formation

11p+

Na atom

1 valence e-

Valence e- lost in ion formation

Effective nuclear charge on remaining e-’s increases.

Remaining e- pulled closer to nucleus. Ionic size decreases.

Result: a smaller Result: a smaller sodium ion, Nasodium ion, Na++

Anion FormationAnion Formation

17p+

Chlorine atom with 7 valence e-

One e- is added to the outer shell (from Na for example).

Effective nuclear charge is reduced and the e- cloud expands.

A chloride ionion is produced. It is larger than the original atom.

#2. Trends in Ionization Energy p.173p.173

Ionization energy - energy required to completely remove e- (from gaseous atom)

energy required to remove only 1st e-called first ionization energy.

Ionization Energy

second IE is E required to remove 2nd e-Always greater than first IE

third IE greater than 1st or 2nd IE IE helps predict what ions elements form Li 1+ Mg 2+ Al 3+

Symbol First Second ThirdHHeLiBeBCNO F Ne

1312 2731 520 900 800 1086 1402 1314 1681 2080

5247 7297 1757 2430 2352 2857 3391 3375 3963

11810 14840 3569 4619 4577 5301 6045 6276

Why did these values increase so much?

Table 6.1, p. 173

Cation FormationCation Formation

11p+

Anion FormationAnion Formation

17p+

What factors determine IE? greater nuclear charge = greater IE Greater distance from nucleus

decreases IE Filled & half-filled orbitals have lower

energyEasier to achieve (lower IE)

Shielding effect

Shielding Effect e-’s in outer PEL

“look thru” other PEL’s to “see” nucleus

Stays same thru blocks

Greater influence on IE than nuclear charge

Shielding Trends

remains constant

increases

Ionization Energy - Group trends p. 174

going down groupfirst IE decreases b/c...

e- further from p+ attractionmore “shielding”

Ionization Energy - Period trends p. 174

Same period atoms have same: # energy levels “shielding” (within a block – slight decrease

btwn “s” and “p”)Increasing nuclear chargeIE generally increases left - right

Exceptions…full & 1/2 full orbitals

Firs

t Ion

izat

ion

ener

gy

Atomic number

He He greater IE than H. Both w/ same

shielding (e- in 1st level) He - greater nuclear

charge

H

Firs

t Ion

izat

ion

ener

gy

Atomic number

H

He

Li lower IE than H more shielding

further away These outweigh

greater nuclear charge

Li

Firs

t Ion

izat

ion

ener

gy

Atomic number

H

He

Be higher IE than Li= shielding

(period) greater nuclear

charge Li

Be

Firs

t Ion

izat

ion

ener

gy

Atomic number

H

He B has lower IE than

Begreater nuclear

chargeshielding has greater

influence on IESlight decrease (“p”

e-) “p” e- removed “s” orbital ½ filled

Li

Be

B

Firs

t Ion

izat

ion

ener

gy

Atomic number

H

He

Li

Be

B

C

Firs

t Ion

izat

ion

ener

gy

Atomic number

H

He

Li

Be

B

C

N

Firs

t Ion

izat

ion

ener

gy

Atomic number

H

He

Li

Be

B

C

N

O

Oxygen breaks the pattern, b/c removing e- leaves it w/ 1/2 filled p orbital

Firs

t Ion

izat

ion

ener

gy

Atomic number

H

He

Li

Be

B

C

N

O

F

Firs

t Ion

izat

ion

ener

gy

Atomic number

H

He

Li

Be

B

C

N

O

F

Ne Ne has a lower

IE than HeBoth full but…

Ne more shieldingb/c greater

distance

Firs

t Ion

izat

ion

ener

gy

Atomic number

H

He

Li

Be

B

C

N

O

F

Ne Na has a lower

IE than Li Both are s1

Na - more shielding Greater

distanceNa

Trends in Ionization Energy (IE)

increases

decreases decreases

Trends in Ionic Size: Cations Cations lose e-’s

metals Cations smaller than atom they came

from lose e-’s lose entire energy level.

Cations of representative elements have noble gas config before them

Trends in Ionic size: Anions Anions gain e-‘s

nonmetals

Anions bigger than atom they came from same energy levelgreater area nuclear charge needs to cover

Configuration of Ions Ions always have noble gas

configurations (full outer level) Na atom is: 1s22s22p63s1

Forms 1+ Na ion: 1s22s22p6 Same as Ne

Configuration of Ions

Non-metals form ions by gaining e-’s to achieve noble gas configurationconfiguration of noble gas after

them

Ion Group trends Each step down a

group adds energy level

Ions - bigger going downmore energy levels

Li1+

Na1+

K1+

Rb1+

Cs1+

Ion Period Trends Across period

nuclear charge increases Ions get smaller

energy level changes btwn anions & cations

Li1+

Be2+

B3+

C4+

N3-O2- F1-

#3. Trends in Electronegativity Electronegativity (EN)- tendency for

atom to attract e-’s when atom in cmpd

Sharing e-, but how equally? Element w/ big EN pulls e- towards

itself strongly!

Electronegativity Group TrendFurther down group, farther

e- away from nucleusplus more e-’s atom has

more willing to shareLow EN

Electronegativity Period Trend Metals let e-’s go easily

low EN

Nonmetals want more e-’stake e-’s from othersHigh EN

Trends in Electronegativity

0

decrease

s

increases

decreases

Chemistry Song "Elemental Funkiness" - Mark Rosengarten

The Elements – Tom Lehrer