UNIT IV – THE PERIODIC TABLE
I. Introduction to the Elements
“The Elements”
Part I
1. Name the original 4 elements believed to exist by Greek philosophers.
earth, air, fire, water
2. Most elements found in Earth are locked in compounds.
3. What metal is the “most important” metal? iron
4. What was the main source of iron that “came from the heavens”? meteorites
5. What is the latin word for lead? plumbum What other word comes from it? plumber
6. What liquid metal is known to cause mental disorders?mercury
7. The compound cinnabar is made from the elements mercury and sulfur.
8. What “military” compound was formed by Chinese alchemists? gunpowder
9. European alchemists, in a quest for wealth, were trying to use base metals to produce gold
10. Pyrite, which looks like gold, is commonly called “fools gold “.
11. In the mid-17th century, what element was isolated from human urine? phosphorus
12. Phosphorus was used at the end of WW II for what type of weapon? firebombs
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UNIT IV – THE PERIODIC TABLE
Part II
1. What scientist defined elements as substances that can’t be broken down? Robert Boyle
2. What animal was used by Joseph Priestly to test the oxygen he created? a mouse (poor thing)
3. Nitrogen makes up about 75 % of the air you breathe.
4. What noble gas is used to fill the chamber in a light bulb? argon
5. What element is used to make filaments for light bulbs? tungsten Why? it has a high melting point
6. Lithium is used in drugs to help what psychological disorder? manic depression
7. List 6 elements essential for living things. (Watch carefully, it moves fast!!!!)
carbon, nitrogen, hydrogen, oxygen, sulfur, calcium, sodium, magnesium, potassium,
phosphorus, iodine, etc. (I know that’s not all of them, I’m doing this off the top of my head)
8. What element is the basic unit for all living things? carbon
9. What happened to the diamond in Lavoisier’s experiment? it burst into flame (coooool!)
10. What happened to Newland’s Law of Octaves? it was discredited, because it didn’t work for
the heavier elements
11. What did the gaps in Mendeleev’s Periodic Table of the Elements represent?
elements that had not yet been discovered
12. What element was discovered 4 years after Mendeleev’s table came out? gallium
13. Name one characteristic of Element #109.
short-lived, man-made
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UNIT IV – THE PERIODIC TABLE
3
II. The Periodic Table
A. A brief history – about 60 elements were known in the early 1800’s; many of their properties
were also categorized such as density, specific heat, atomic spectra, atomic mass, etc.
* can they be organized?
1. Dobereiner’s Triads (1829) – found some elements seem to occur in groups of three
* example:
Li
Na
K
DENSITY:
0.534g/mL
0.971g/mL 0.86g/mL
ATOMIC MASS:
6.941
22.98977
39.0983
23.02 note how close this is to the
Average Li and K:
actual atomic mass of sodium
* fell apart because pattern didn’t hold for all elements
2. Newland’s Law of Octaves (1864) – similar elements occur in intervals of 8
Li
Be
B
C
N
O
F
Na
Mg
Al
Si
P
S
Cl
K
3. Mendeleev’s Periodic Table (1869)
* put elements in increasing atomic mass order like Newland, but he then
put elements with similar properties in columns
* 3 pairs of elements were “switched”, so he ignored their atomic masses and
put them in the appropriate columns anyway
examples: Te/I, K/Ar, Co/Ni
* predicted some “missing” elements that weren’t in his table; he assumed they
must be undiscovered elements
* example: “ekasilicon” – missing spot below silicon on Mendeleev’s table:
atomic mass
density
melting point
color
Ekasilicon
72
5.5
high
gray
Germanium
72.59
5.35
947
gray
* In 1886, Germanium was discovered, and it fit ekasilicon well
4. Moseley (1913)
* discovered atomic number through his work with X-rays
* Modern Periodic Law – when placed in order of atomic number the physical
and chemical properties of the elements show a periodic pattern
B. Reading the Periodic Table
* group or family – a vertical column on the table; show similar properties
How are they labeled?
Old School – IA,IIA,etc. (see your table)
IUPAC – 1,2,3,etc.
* period – horizontal row on the table
UNIT IV – THE PERIODIC TABLE
4
C. Metals vs. Nonmetals – Part A of “LAB – Periodic Law” fits well here
Property
Metals
Nonmetals
ionization energy
low
high
electronegativity
low
high
luster
high
low
deformability
malleable and ductile
brittle
conductivity
good
poor
phase at STP
mostly solids
mostly gases and solids
ion formation
loses electrons to form cations (+) gains electrons to form anions (-)
* “staircase” – separates metals from non metals; metals on left, nonmetals on right
* metalloid or semimetal – elements that show properties of both metals and nonmetals
- all elements touching staircase except aluminum
III. Valence Electrons – electrons in the outermost energy level of an atom
T.
1) Aluminum: [Ne] 3s23p1
3 valence electrons
2) Bromine: [Ar] 4s23d104p5
7 valence electrons
3) Potassium [Ar] 4s1
1 valence electron
* easier to know them by column on the periodic table – look at numbers above column
S. How many valence electrons are there in:
4
1) Silicon
2) Krypton
8
3) Magnesium
2
6
4) Oxygen
1A 2A 3B 4B 5B 6B 7B 8B 8B 8B 1B 2B 3A 4A 5A 6A 7A 8A
Column
Number
Valence
Electrons
1
1
H
3
Li
11
Na
19
K
37
Rb
55
Cs
87
Fr
2
4
Be
12
Mg
20
Ca
38
Sr
56
Ba
88
Ra
X
X
X
X
21
Sc
39
Y
71
Lu
103
Lr
22
Ti
40
Zr
72
Hf
104
23
V
41
Nb
73
Ta
105
24
Cr
42
Mo
74
W
106
57
La
89
Ac
58
Ce
90
Th
59
Pr
91
Pa
60
Nd
92
U
X
25
Mn
75
Re
107
X
X
X
X
X
3
26
Fe
44
Ru
76
Os
108
27
Co
45
Rh
77
Ir
109
28
Ni
46
Pd
78
Pt
110
29
Cu
47
Ag
79
Au
111
30
Zn
48
Cd
80
Hg
112
5
B
13
Al
31
Ga
49
In
81
Tl
113
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
4
5
6
6
C
14
Si
32
Ge
50
Sn
82
Pb
114
7
N
15
P
33
As
51
Sb
83
Bi
8
O
16
S
34
Se
52
Te
84
Po
116
68
Er
69
Tm
70
Yb
7
9
F
17
Cl
35
Br
53
I
85
At
8
2
He
10
Ne
18
Ar
36
Kr
54
Xe
86
Rn
118
UNIT IV – THE PERIODIC TABLE
IV. Patterns in the Periodic Table
A. Ionization Energy – the amount of energy required to remove the first electron from an atom
* higher IE = “harder” to remove electrons
* trends – see table on top of p.6
L R in a row: ionization energy increases T B in a column: ionization energy decreases
* note that although there are exceptions, these rules are pretty good
S.
1) Rank the following in order of increasing ionization energy: boron, oxygen, fluorine, carbon
Boron, Carbon, Oxygen, Fluorine
2) Rank the following in order from the easiest to remove electrons from to the hardest:
rubidium, sodium, lithium, cesium
Cesium, Rubidium, sodium, lithium
B. Electronegativity – how badly an atom “wants” to gain electrons
* trends – see table on bottom of p.6
L R in a row: electronegativity increases
T B in a column: electronegativity decreases
S.
1) Rank the following in order of decreasing electronegativity: bromine, chlorine, fluorine, iodine
Fluorine, Chlorine, Bromine, Iodine
2) Rank the following in order of increasing electronegativity: boron, oxygen, fluorine, carbon
Boron, Carbon, Oxygen, Fluorine
C. Atomic Radius – the size of an atom
* trends – see table on p. 7
L R in a row: atomic radius decreases
T B in a column: atomic radius increases
S. Rank the following from smallest to largest atomic radius:
1) silicon, chlorine, sodium, sulfur
Chlorine, Sulfur, Silicon, Sodium
2) nitrogen, antimony, phosphorus, arsenic
Nitrogen, Phosphorus, Arsenic, Antimony
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UNIT IV – THE PERIODIC TABLE
6
Table of Ionization Energy
* Ionization Energy is expressed in kJ/mol
H
He
1210
2370
Li
Be
B
C
N
O
F
Ne
621
900
799
1088
1405
1314
1682
2079
Na Mg
Al Si
496
738
577
K
Ca
Ga Ge As Se Br Kr
418
589
577
787
761
P
S
1060
999
946
941
Rb Sr
In Sn Sb Te
402
557
548
707
833
870
Cl Ar
1256
1142
1520
1351
I
Xe
1008
1172
Cs Ba
Tl Pb Bi Po At Rn
377
690
602
715
703
812
???
1036
Table of Electronegativity
* Values are given using the Pauling scale, in which fluorine (F) is given an arbitrary value of 4.0 (the
highest possible), and scaled down proportionately
H
He
2.1
Li Be
B
C
N
O
F Ne
1.0
2.0
2.5
3.0
3.5
4.0
1.5
Na Mg
0.9
1.2
K
Ca
0.8
1.0
Rb Sr
0.7
0.9
Al Si
P
S Cl Ar
1.5
2.1
2.5
1.8
3.0
Ga Ge As Se Br Kr
1.6
1.8
2.0
2.4
In Sn Sb Te
1.7
1.8
1.9
2.1
2.8
I
Xe
2.5
Cs Ba
Tl Pb Bi Po At Rn
0.7
1.8
0.9
1.9
1.9
2.0
2.2
UNIT IV – THE PERIODIC TABLE
Li
0.152
Na
0.186
K
0.231
Rb
Table of Atomic Radii (measured in nm)
Be
B
C
N
Cs
F
0.088
0.077
0.070
0.066
0.064
Mg
Al
Si
P
S
Cl
0.143
0.117
0.110
0.104
0.099
0.160
Ca
Ga
Ge
As
Se
Br
0.122
0.122
0.121
0.116
0.115
In
Sn
Sb
Te
I
0.140
0.141
0.137
0.133
Tl
Pb
Bi
Po
At
0.171
0.175
0.146
0.140
0.140
0.197
Sr
0.215
Ba
0.220
0.262
O
0.111
0.162
0.244
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UNIT IV – THE PERIODIC TABLE
8
V. Groups in the Periodic Table – Part B of “LAB – Periodic Law” fits well here
A. Alkali Metals – column IA or 1 1 valence electron
1) Properties
a) metallic – shiny, malleable, ductile, good conductors
b) low melting points & low densities – see p.4
c) soft enough to be cut with a knife
d) VERY reactive – react violently with water
* as a result, they are never seen in metallic form
* must be stored in oil
e) react to form +1 ions
* Why? all atoms “want” 8 valence electrons, so the alkali metals
shed their one valence electron so that the previous shell
becomes the new outer shell & it has 8 valence electrons
2) Sources and uses
a) table salt (NaCl), lye (NaOH), bleach (NaClO), baking soda (NaHCO3)
b) potash (KNO3), lithium carbonate (Li2CO3)
c) K and Na are very abundant in crust and in oceans
B. Alkaline Earth Metals – column IIA or 2 2 valence electrons
1) Properties
a) metallic; somewhat soft and pliable
b) higher melting points and densities than the alkali metals
c) reactive – Ba will react with water, others will react with air; form +2 ions
2) Sources and uses
a) never found in metallic form – too reactive
b) Ca and Mg are most abundant: limestone (CaCO3) and magnesite (MgCO3)
c) magnesium metal is used in aircraft, wheels, tools
d) beryllium is very strong, lightweight, and rare
C. Transition Metals – d-block elements; columns IIIB – II B or 3-12 valence not as important
* most are high in density and fairly unreactive, therefore can be found in metallic form
1) Chromium – often called chrome
a) resists corrosion well
b) very shiny – alloyed with iron and nickel for bumpers, rims, etc.
c) many chromium compounds are colorful – used in paints
d) known carcinogen
2) Iron – very abundant metal on the earth
a) strength and durability makes it an important industrial material
b) moderately reactive – rusts easily to form iron oxide (Fe2O3)
c) important component of hemoglobin in red blood cells – important nutrient
3) Copper
a) soft metal with orangish color (only other colored metal is gold)
b) used for coins and pipes
c) only silver is better conductor, so used in wires
4) Silver
a) good conductor – used in electrical equipment
b) used for jewelry, silverware, etc. – sterling silver is alloy w/ 7.5% copper
c) resists corrosion, but tarnishes easily with sulfur (Ag2S)
5) Gold
a) very dense and malleable
b) resists corrosion well – used in jewelry
c) yellow in color
UNIT IV – THE PERIODIC TABLE
D. Inner Transition Metals (Rare Earths) – f-block
* all have VERY similar properties to each other
1) Lanthanides (4f row) - rare and have little commercial use
* soft, silvery metals, react to form +3 ions, reactive
2) Actinides (5f row)- radioactive elements
* only two (U and Th) occur in nature; others are made artificially
E. Boron Group – IIIA or 13 – few characteristics in common; 3 valence electrons
1) Aluminum – relatively reactive; likes to form +3 ions
a) found in bauxite (Al2O3), #3 element on Earth by mass (#1 of the metals)
b) strong, resistant to corrosion, low in density; many commercial uses
F. Carbon Group – IVA or 14 – few characteristics in common; 4 valence electrons
1) Carbon – nonmetal found in limestone (CaCO3) and fossil fuels
a) forms millions of different compounds because of its bonding ability
b) 3 forms (allotropes): amorphic, graphite, diamond (buckyball?)
c) building block of all organic molecules
2) Silicon – metalloid found in many silica minerals like quartz (SiO2)
a) #2 element on Earth by mass, used in glass and computer chips
3) Tin and lead – metals found in many places
a) used in cans (tin), and batteries (lead)
G. Nitrogen Group – VA or 15; 5 valence electrons
1) Nitrogen – found primarily in the atmosphere in free state (N2) – colorless, inert gas
a) bacteria “fix” it in the nitrogen living cycle
b) major component of ammonia (NH3)
2) Phosphorus – found in many fertilizers, important component of DNA
H. Oxygen Group – VIA or 16; 6 valence electrons; react to form -2 ions
1) Oxygen – #1 on Earth by mass, found in air (O2), water (H2O), and earth (SiO2)
a) O2 is colorless, odorless, tasteless gas – important in respiration
b) also found in atmosphere as ozone (O3) – filters out UV radiation
2) Sulfur – found often in free state (S8) in the earth’s crust
a) “rotten egg” smell is H2S gas – added to natural gas (CH4)
b) sulfuric acid (H2SO4) is used a great deal in industry
I. Halogens – VIIA or 17; 7 valence electrons; react to form -1 ions
1) when found in the free state, all are diatomic (F2 , Cl2 , Br2 , I2 , At2)
2) very reactive, so rarely found in free state
3) fluorine is used to make fluoride (F-) compounds, also in CFC’s (refrigerants)
* in its molecular form (F2) it is a yellow, reactive, poisonous gas
4) chlorine is used as disinfectant, bleach (NaClO) and in plastics (PVC)
* in its molecular form (Cl2) it is a green, reactive, poisonous gas
5) bromine in its molecular form (Br2) is an orange liquid
6) iodine is found in iodized salt and tincture of iodine (dissolved in alcohol)
* in its molecular form (I2) it is a purplish solid
J. Noble Gases – VIIIA or 18; 8 valence electrons (stable octet); don’t ever form ions
1) unreactive, odorless, tasteless gases found only in free state in the atmosphere
2) a few compounds (with Xe) have been made in labs
3) used in light bulbs and as supercoolants
K. Hydrogen – in group IA with the alkalai metals (1 valence electron) – not a metal though
1) doesn’t form +1 ions as easily, and not as reactive
2) found in water (H2O) and in free state (H2), and in many carbon compounds
3) most common element in the universe (95%)
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UNIT IV – THE PERIODIC TABLE
10
Properties of Common Elements
Name
aluminum
antimony
argon
arsenic
barium
beryllium
bismuth
boron
bromine
calcium
carbon
chlorine
chromium
cobalt
copper
fluorine
germanium
gold
helium
hydrogen
iodine
iron
lead
lithium
magnesium
manganese
mercury
neon
nickel
nitrogen
oxygen
phosphorus
platinum
plutonium
potassium
radium
radon
silicon
silver
sodium
strontium
sulfur
tin
titanium
tungsten
uranium
xenon
zinc
Appearance at
Room Temperature
Density
(g/cm3)
Melting Point (oC)
silver metal
2.70
silver metal
6.68
colorless gas
1.78*
gray metalloid
5.73
silver metal
3.51
gray metal
1.85
silver metal
9.80
black solid
2.34
red-brown liquid
3.12
silver metal
1.54
diamond
3.51
graphite
2.26
green-yellow gas
3.21*
silver metal
7.20
silver metal
8.9
red metal
8.92
yellow gas
1.69*
gray metalloid
5.36
yellow metal
19.3
colorless gas
1.79*
colorless gas
0.089*
blue-black solid
4.93
silver metal
7.87
silver metal
11.4
silver metal
0.634
silver metal
1.74
silver metal
7.2
silver metal
13.6
colorless gas
0.900*
silver metal
8.90
colorless gas
1.25*
colorless gas
1.43*
yellow solid
1.82
silver metal
21.4
silver metal
19.8
silver metal
0.86
silver metal
5
colorless gas
9.73*
gray metalloid
2.33
silver metal
10.5
silver metal
0.971
silver metal
2.54
yellow solid
2.07
silver metal
7.31
silver metal
4.54
gray metal
19.3
silver metal
19.0
colorless gas
5.89*
silver metal
7.13
* Densities of gases are given in g/ L at STP
660
631
-189
613
726
1280
271
2079
-7
839
3550
3367 (sublimes)
-101
1880
1495
1083
-220
937
1063
---259
114
1535
328
181
849
1244
-39
-249
1455
-210
-218
44
1772
641
64
700
-71
1410
962
98
769
113
232
1660
3410
1132
-112
420
Boiling
Point (oC)
2467
1750
-186
---1640
2970
1560
3675
59
1484
4827
---35
2672
2870
2567
-188
2830
2966
-269
-253
184
2750
1740
1342
1107
1962
357
-246
2730
-196
-183
280
3800
3232
774
1140
-62
2355
2212
883
1384
445
2260
3287
5660
3818
-107
907
UNIT IV – THE PERIODIC TABLE
11