Page 372 - The Veterinary Laboratory and Field Manual 3rd Edition

Clinical chemistry 341

Figure 7.10 Atomic structure of
carbon.

with other elements to form a compound com- Table 7.4 International atomic
posed of two or more types of atom. A molecule is weights of selected elements.
the smallest particle of an element or compound
which can exist independently; the relative Name Symbol Atomic weight*
mass of a molecule is known as its molecular Aluminium Al 26.98
weight. Arsenic As 74.91
Bromine Br 79.916

oxidation and reduction Calcium Ca 40.08
Carbon C 12.011
Oxidation is defined as a reaction in which an Chlorine Cl 35.457
atom loses electrons (usually the combination Copper Cu 63.54
of oxygen with a substance or the removal of Hydrogen H 1.008
hydrogen from it). Reduction is a reaction in Iron Fe 55.85
which an atom gains electrons (usually the Magnesium Mg 24.32
removal of oxygen from a substance or the addi-
tion of hydrogen to it). Nitrogen N 14.01
Oxygen O 16.00
Phosphorous P 30.98
Electrolytes and electrolysis Potassium K 39.10
Selenium Se 78.96
Electrolytes are acids, bases or salts that con- Sodium Na 22.99
duct electric current when dissolved in water.
Positively charged particles are known as cations Notes: *Atomic weight = relative atomic mass. For natural
elements with more than one isotope, it is an average for a
and negatively charged particles are known as mixture of isotopes. This is different from the atomic number
anions. In an electrolytic system (for example, a which relates to the position of the elements in the periodic table.
battery), positively charged particles (for exam-
ple, Na ) are attracted to the –ve pole (cathode)
+
and negatively charged particles (for example,
Cl ) are attracted to the +ve pole (anode).
–

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