22
Chapter 2
containing such atoms. Free radicals are unstable molecules
that can react with other atoms, through the process known as
oxidation. When a free radical oxidizes another atom, the free
radical gains an electron and the other atom usually becomes
a new free radical.
Free radicals are formed by the actions of certain
enzymes in some cells, such as types of white blood cells
C
O
C
O
Methane (CH
4
)
Ammonia (NH
3
)
Water (H
2
O)
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Table 2–3
lonic Forms of Elements Most Frequently Encountered in the Body
Chemical Atom
Symbol
Ion
Chemical Symbol
Electrons Gained or Lost
Hydrogen
H
Hydrogen ion
H
+
1 lost
Sodium
Na
Sodium ion
Na
+
1 lost
Potassium
K
Potassium ion
K
+
1 lost
Chlorine
Cl
Chloride ion
Cl
1 gained
Magnesium
Mg
Magnesium ion
Mg
2+
2 lost
Calcium
Ca
Calcium ion
Ca
2+
2 lost
Figure 2–2
Three different ways of representing the geometric
confi guration of covalent bonds around the carbon, nitrogen,
and oxygen atoms bonded to hydrogen atoms.
Figure 2–3
Changes in molecular shape occur as portions of a
molecule rotate around different carbon-to-carbon bonds,
transforming this molecule’s shape, for example, from a
relatively straight chain (top) into a ring (bottom).
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