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Essential Elements
Li
3
He
2
C
6
N
7
O
8
F
9
Ne
10
Na
11
B
5
Be
4
H
1
Al
13
Si
14
P
15
S
16
Cl
17
Ar
18
K
19
Ca
20
Sc
21
Ti
22
V
23
Cr
24
Mn
25
Fe
26
Co
27
Ni
28
Cu
29
Zn
30
Ga
31
Ge
32
As
33
Se
34
Br
35
Kr
36
Rb
37
Sr
38
Y
39
Zr
40
Nb
41
Mo
42
Tc
43
Ru
44
Rh
45
Pd
46
Ag
47
Cd
48
In
49
Sn
50
Sb
51
Te
52
I
53
Xe
54
Cs
55
Ba
56
Hf
72
Ta
72
W
74
Re
75
Os
76
Ir
77
Pt
78
Au
79
Hg
80
Tl
81
Pb
82
Bi
83
Po
84
At
85
Rn
86
Mg
12
La
57
Elements in organic matter
Major minerals
Trace elements
Davis, Metcalfe, Williams, Castka, Modern Chemistry, 1999, page 748
Trace Elements in Biological Systems
• Of the 100 known elements, 28 are known to be essential for the growth of at least one biological species, and only 19 are essential to humans.
• The following makes some elements essential:
1. The element must have some unique chemical property that an organism can use to its advantage and without which it
cannot survive.
2. Adequate amounts of the element must be available in the environment in an easily accessible form.
• Many of the elements essential to life are necessary in only small amounts (trace elements).
Copyright 2007 Pearson Benjamin Cummings. All rights reserved.
Oxidation States of Elements
1
3 4 5 6 7
Groups 8
2
F1-
Br1-
I1-
Cl1-
Transition metals form cationswith various charges.
O2-
S2-
Se2-
Te2-
Be2+
Te2-
Te2-
Te2-
Te2-
Li1+
Na1+
K1+
Rb1+
Cs1+
Al3+
Ga3+
In3+
Zn2+
Ag1+
Chemical Bonding
• Ionic– Metal (cation) with non-metal (anion)– Transfer of electron(s)– Strong bond…high melting point
• Covalent– Non-metal with non-metal– Sharing of electron(s)
• Non-polar (equal distribution of electrons)• Polar (uneven electron distribution)
– Weak bonds…low melting points• Single, double and triple bonds
• Metallic (nuclei in a “sea” of shared electrons)
First Four Energy Levels
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 334
Modern Atomic Structure
n = 1
n = 2
n = 3
n = 4
Hein, Arena, Foundations of College Chemistry, 2000, page 202
1s
2s
3s
4s
2p
3p
4p
3d
4d 4f
Sublevel designation
An orbital for a hydrogenatom. The intensity of the dots shows that the electronspends more time closer tothe nucleus.
The first four principal energylevels in the hydrogen atom.Each level is assigned aprincipal quantum number n.
The types of orbitals on eachof the first four principalenergy levels.