chapter 6 the periodic table p. 154 the elements by tom lehrer the elements by tom lehrer
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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 #
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
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