Periodic Properties of the Elements

1
Chapter 7

• Periodic Properties of the Elements

2
Atomic Radius

• difficult to determine
• Trends
• decreases from left to right across a period
• reason increase in nuclear charge with only
  small increase in shielding (increase in
  effective nuclear charge)
• Zeffective

3

• Zeffective Z ??( subvalence s e)
• ??( subvalence p e)
• ??( subvalence d e)
• ??( subvalence f e)
• ? gt ? gt ? gt ?

4
Atomic Radius Trend

• increases down a group
• reason adding shells

5
1A
1
H
3
Li
11
Na
19
K
37
Rb
55
Cs
87
Fr
6
Lanthanide Contraction

• inordinately large decrease in atomic radius
  between lanthanum and hafnium
• causes Hf and Zr to be about same size

7

• for a given element
• anion gt neutral atom gt cation

8

• for a given element
• anion gt neutral atom gt cation
• eg

H
9

• for a given element
• anion gt neutral atom gt cation
• eg

H
H
10

• for a given element
• anion gt neutral atom gt cation
• eg

H
H
H
11
Ionization Energy

• energy required to remove the most loosely held
  electron from a gaseous atom
• eg.
• Na(g) ? Na(g) e ?H IE1
• Na(g) ? Na(g)2 e ?H IE2
• endothermic

12
H 1312 Ionization Energies (kJ/mole) He 2371 52
47 Li 520 7297 11810 Be 900 1757 14840 21000 B 800
2430 3659 25020 32810 C 1086 2352 4619 6221 37800
47300 N 1402 2857 4577 7473 9443 53250 64340 O 13
14 3391 5301 7468 10980 13320 71300 84850 F 1681 3
375 6045 8418 11020 15160 17860 92000 Ne 2080 3963
6276 9376 12190 15230 Na 496 4565 6912 9540 13360
16610 20110 25490 Mg 738 1450 7732 10550 13620 18
000 21700 25660 Al 577 1816 2744 11580 15030 18370
23290 27460 Si 786 1577 3229 4356 16080 19790 237
80 29250 P 1012 1896 2910 4954 6272 21270 25410 29
840 S 1000 2260 3380 4565 6996 8490 28080 31720 Cl
1255 2297 3850 5146 6544 9330 11020 33600 Ar 1520
2665 3947 5770 7240 8810 11970 13840 K 419 3069 4
600 5879 7971 9619 11380 14950
13
He
Ne
F
Ar
Kr
N
Cl
O
H
Br
P
IE 1
C
As
Zn
Be
S
Se
Si
B
Ge
Mg
Li
Ga
Al
Na
K
Rb
Z
14
He
Ne
F
Ar
Kr
N
Cl
O
H
Br
P
IE 1
C
As
Zn
Be
S
Se
Si
B
Ge
Mg
Li
Ga
Al
Na
K
Rb
Z
15
He
Ne
1s22s2
F
Ar
Kr
N
Cl
O
H
Br
P
IE 1
C
As
Zn
Be
S
Se
Si
B
Ge
Mg
Li
Ga
Al
Na
1s22s1
K
Rb
Z
16
He
Ne
1s22s2
F
Ar
Kr
N
Cl
O
H
Br
P
IE 1
C
As
Zn
Be
S
Se
Si
B
Ge
Mg
1s22s22p1
Li
Ga
Al
Na
1s22s1
K
Rb
Z
17
He
Ne
1s22s2
F
Ar
Kr
N
Cl
O
H
Br
P
IE 1
C
As
Zn
Be
S
2s22p2
Se
Si
B
Ge
Mg
1s22s22p1
Li
Ga
Al
Na
1s22s1
K
Rb
Z
18
He
Ne
1s22s2
F
Ar
2p3
Kr
N
Cl
O
H
Br
P
IE 1
C
As
Zn
Be
S
2s22p2
Se
Si
B
Ge
Mg
1s22s22p1
Li
Ga
Al
Na
1s22s1
K
Rb
Z
19
He
Ne
1s22s2
F
Ar
2p3
Kr
N
Cl
O
H
2p4
Br
P
IE 1
C
As
Zn
Be
S
2s22p2
Se
Si
B
Ge
Mg
1s22s22p1
Li
Ga
Al
Na
1s22s1
K
Rb
Z
20
He
Ne
1s22s2
2p5
F
Ar
2p3
Kr
N
Cl
O
H
2p4
Br
P
IE 1
C
As
Zn
Be
S
2s22p2
Se
Si
B
Ge
Mg
1s22s22p1
Li
Ga
Al
Na
1s22s1
K
Rb
Z
21
He
2p6
Ne
1s22s2
2p5
F
Ar
2p3
Kr
N
Cl
O
H
2p4
Br
P
IE 1
C
As
Zn
Be
S
2s22p2
Se
Si
B
Ge
Mg
1s22s22p1
Li
Ga
Al
Na
1s22s1
K
Rb
Z
22
Electron Affinity

• the energy change associated with the addition of
  an electron to a gaseous atom or ion
• usually exothermic
• eg F e ? F
• Na e ? Na

23
1s22s2
Be
Mg
Ca

Ar
1s2
Electron Affinity
He
Ne
2s22p3
N
0
2s22p1
P
K
1s1
Li
2s22p4
B
H
Na
Al
O
2s22p2
Si
C

1s22s1
S
2s22p5
F
Cl
Z
24

• Metals Nonmetals
• solid solid, liquid, or gas
• malleable ductile brittle if solid
• lose e ? cations gain e ? anions
• oxides are basic oxides are acidic
• react with acids react with bases
• to form salts to form salts
• photoelectric effect no
• thermionic effect no

25

• metal oxide water ? metal hydroxide
• eg MgO H2O ? Mg(OH)2
• nonmetal oxide water ? oxoacid
• eg SO2 H2O ? H2SO3
• metal oxide acid ? salt water
• eg CaO 2HNO3 ? Ca(NO3)2 H2O
• nonmetal oxide base ? salt water
• eg SO2 Ba(OH)2 ? BaSO3 H2O
• metal nonmetal ? salt
• eg 2 Na Cl2 ? 2NaCl

26
Trends in Metallic Character

• increases from right to left across period
• increases down a group in main group

27
Alkali Metals

• have 1 valence e
• most metallic and reactive
• soft
• low density
• low tm (eg Cs, Tm 29C)
• Li is lightest metal
• Li, Na, K less dense than water
• Na commonly used as cooling fluid due to high
  thermal conductivity and large liquid range
  (97.5C 880C)

28

• ? bright colors in flames
• Li - red
• Na - yellow, K - lilac, Rb - purple, Cs - blue
• not found in elemental form in nature
• occur mostly as chlorides in salt deposits, in
  seawater, and in subterranean brines
• salt deposits have least soluble salts on bottom
  and most soluble on top
• alkali metal salts on top, eg rock salt (NaCl)
  and sylvite (KCl)
• seawater contains 0.48M Na

29
Reactions of the Alkali Metals

• VERY reactive
• react violently with halogens to produce ionic
  halides
• eg 2K Br2 ? 2KBr
• react violently with hydrogen to produce ionic
  hydrides
• eg 2Na H2 ? 2NaH
• Lithium reacts with nitrogen
• 6Li N2 ? 2Li3N
• good reducing agents

30
Reactions With Oxygen

• 4Li O2 ? 2Li2O
• lithium oxide
• 4 Na O2(limited) ? 2Na2O
• sodium oxide
• oxide ion, O2
• 2 Na O2(xs) ? Na2O2
• sodium peroxide
• peroxide ion, O22

31

• K O2 ? KO2
• potassium superoxide
• superoxide ion, O2
• Rb O2 ? RbO2
• rubidium superoxide
• Cs O2 ? CsO2
• cesium superoxide

32
Alkali Metal Compounds
33
Hydroxides

• all alkali metals react violently with water to
  form corresponding hydroxide, hydrogen, and heat
• 2K 2H2O ? 2KOH H2 ?
• alkali metal oxides also react with water to form
  hydroxide
• Li2O H2O ? 2LiOH
• white, crystalline solids, strong bases
• deliquescent
• (absorb enough water from atmosphere to dissolve
  themselves)

34
NaOH

• sodium hydroxide, lye, caustic soda
• industrial base
• used in production of textiles, cleaners, soap,
  paper, pulp, and in petroleum refining

35
Alkali Metal Halides

• colorless, crystalline solids (white)
• prepared by
• 1. direct combination of the elements
• eg 2K Cl2 ? 2KCl
• 2. reaction of acid with alkali metal hydroxide
• eg CsOH HCl ? CsCl H2O
• NaCl primary source of most Na and Cl Ctg.
  compounds. Used also in foods, HCl, NaOH, and Cl2
  production

36
Carbonates

• K2CO3 potash
• Na2CO3 soda ash
• Na2CO3 used in manufacture of glass, paper,
  detergents, and soap. In home used for washing,
  cleaning, water softening

37
Sources

• trona
• Na2CO3.NaHCO3.2H2O
• found in dry lake beds in Wyoming
• solvay process
• CaCO3 ????CaO CO2
• CO2 NaCl H2O NH3???NaHCO3 NH4Cl
• CaO 2NH4Cl ? CaCl2 H2O 2NH3

38
Sodium Bicarbonate

• NaHCO3
• sodium hydrogen carbonate
• baking soda
• made by CO2 NaOH ? NaHCO3
• weak base
• used in cooking and medicine
• baking powder NaHCO3 weak acid
• eg NaH2PO4

39

• HCO3 H ? CO2 H2O
• 2NaHCO3 ????Na2CO3 CO2 H2O
• Sodium Sulfate Na2SO4, paper production
• Sodium Bisulfate NaHSO4, weak acid, used in
  cleaners

40
Alkaline Earth Metals

• harder
• more dense
• less reactive
• 2 valence electrons
• form 2 ions
• Be Mg have structural applications
• flame tests
• Ca ? orange-red
• Sr ? deep red
• Ba ? pale green

41
Sources

• seawater, underground brines, salt deposits
• Magnesium
• seawater
• magnesite MgCO3
• dolomite MgCa(CO3)2
• epsomite MgSO4.7H2O
• Calcium
• CaCO3 chalk, limestone, marble
• hydroxyapatite Ca5(PO4)3OH

42
Uses of Magnesium

• the lightest structural metal
• aircraft, luggage, etc.
• alloys even more useful
• sacrificial anode for corrosion protection

43
wire
pipe
Mg
Mg ? Mg2 2e
metal ship hull
Mg ? Mg2 2e
Mg plates
44
wire
pipe
2e
Mg
Mg ? Mg2
metal ship hull
2e
Mg ? Mg2
Mg plates
45
wire
pipe
e
e
e
Mg
Mg ? Mg2
metal ship hull
e
e
e
Mg ? Mg2
Mg plates
46
Reactions and Compounds

• Be forms mostly covalent compounds
• Mg forms some covalent compounds and some ionic
  compounds
• others form mostly ionic compounds
• all burn in air to form oxide
• eg 2Ca O2 ? 2CaO
• Mg also forms nitride
• 3Mg N2 ? Mg3N2

47

• Be will not react with cold water, hot water, or
  even with steam
• Mg will react with hot water and with steam
• Mg 2H2O(l)(hot) ? Mg(OH)2 H2
• Mg H2O(g) ? MgO H2
• all other alkaline earth metals will also react
  with cold water
• eg Ca 2H2O ? Ca(OH)2 H2

48
Calcium Carbonate

• chalk, marble, limestone

49
Lime

• CaCO3 ????CaO CO2
• used in steel making
• in farming used to neutralize acid in soil and
  provide calcium
• water treatment
• CaO H2O ? Ca(OH)2
• 3Ca(OH)2 2AlCl3 ? 2Al(OH)3 3CaCl2

50
Mortar

• CaO, water, and sand
• CaO H2O ? Ca(OH)2
• Ca(OH)2 CO2 ? CaCO3 H2O

51
Water Softening

• Ca(OH)2 ? Ca2 2OH
• 2HCO3 2OH ? 2CO32 2 H2O
• Ca2 CO32 ? CaCO3(s)
• Mg2 CO32 ? MgCO3(s)

52
Calcium Chloride

• CaCO3 2HCl ? CaCl2 H2O CO2
• used in de-icing roads
• deliquescent
• used for dust control
• drying agent
• ? CaCl2.H2O, CaCl2.2H2O, CaCl2.6H2O

53
Bones and Teeth

• hydroxyapatite
• Ca5(PO4)3OH
• fluoride treatment
• Ca5(PO4)3OH F ? Ca5(PO4)3F OHhydroxyapatite
  fluoroapatite
• fluoroapatite, weak base, less soluble than
  hydroxyapatite

54

• Ca needed for vision, maintaining heart rythm,
  blood clotting
• Mg needed for enzymes, nerve impulse
  transmission, muscle contraction, CH metabolism,
  photosynthesis
• Be and Ba highly toxic
• Be light and strong, structural
• BaSO4 highly insoluble, opaque to x-rays, used
  as x-ray contrast medium

55
Hydrogen

• 1s1
• most abundant element in universe, 9th in Earths
  crust
• does not belong to any group
• nonmetal
• colorless, odorless gas, H2, nontoxic but will
  not support life
• forms molecular compounds with nonmetals, eg H2O
• reacts with active metals to form solid metal
  hydrides (H)

56
Compounds of Hydrogen

• reacts with metals to form hydrides, eg. NaH,
  MgH2
• reacts with nonmetals to form covalent compounds,
  eg. H2O, CH4
• Water
• H2 1/2O2 ? H2O ?H 286 kJ
• rocket fuel
• mixtures of H2 and O2 explosive

57
Ammonia

• made by Haber process
• N2 3 H2 ? 2NH3(g)
• high pressure, high T, catalyst
• colorless gas, foul odor, irritating
• primary use - fertilizer, pure or converted to
  (NH4)2SO4, (NH4)2HPO4, or urea (NH2)2CO
• cleaning agent

58
Methane

• CH4
• colorless, odorless, tasteless gas
• primary source - natural gas
• primary use - fuel

59
Chalcogens

• 6 valence electrons
• form 2 ions (except for Te and Po)
• oxygen colorless, odorless gas, nonmetal
• sulfur yellow solid, nonmetal
• selenium solid, nonmetal
• tellurium solid, metalloid
• polonium solid, radioactive, metal

60
Oxygen

• 2 allotropes
• O2 oxygen, colorless, odorless, tasteless gas,
  nontoxic, supports life
• O3 ozone, pale blue gas, pungent odor, toxic

61
Production

• Liquefication of Air
• air cooled to liquefy, components separated by
  distillation
• Electrolysis of Water
• very pure oxygen, expensive
• Heating of Potassium Chlorate
• in presence of MnO2 catalyst
• small scale
• 2KClO3(s) ? 2KCl(s) 3O2

62

• oxygen reacts directly with most other elements,
  combustion
• only noble gases, Au, and Pt will not react
  directly with oxygen
• generally exothermic
• produces oxides, eg. CO2, MgO, H2O, SO2

63
Sulfur

• found as free element in volcanic regions
• yellow solid, S8
• brimstone
• found also combined, anhydrite (CaSO4)
• most productive deposits in TX and LA
• mined by the Frasch process

64
Frasch Process
compressed air
liquid sulfur
solid sulfur
150C H2O
99.5 pure
liquefied sulfur
solid sulfur soil
65

• gypsum, CaSO4.2H2O
• pyrite, FeS2
• galena, PbS, important source of Pb
• chalcocite, Cu2S, important source of Cu
• smelting
• Cu2S O2 ? 2Cu SO2
• SO2 H2S ? S8 H2O