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.