- Chemistry Review
- Soil chemical properties
- inorganic colloids
- organic colloids
- Affect the ability to supply nutrients for
- Affect the fate of chemicals added to the soil.
- organic wastes
- herbacides .
|Element||A single substance which can't be decomposed by ordinary chemical means. Ex. Ca, Na, S, N, P, K, Al, Mg, Mn. There are 118 known elements, singly or in combination. They constitute all matter.|
|Atom||The smallest uncharged part of an element that maintains its chemical identity.|
|Compound||A substance which is made up of 2 or more elements in fixed proportions. Can be decomposed by chemical means.|
|Molecule||The smallest particle of an element or compound capable of retaining chemical identity. Ex. water (H2O) or table salt (NaCl)|
|Ion||An atom or molecule that has electrical charge|
|Cations||Positively charged ions --- Ex. Ca 2+, Mg2+, K+, Al3+,H+|
|Anions||Negatively charged ions --- Ex. NO3-, (PO4)3-, SO4-2|
|Valence||The charge of the ion is called its valence. Ex. Ca has a valence of 2+. Other examples are: Al+3 , Na+, Ca+2, Mg+2, NO3-, (S04)-2|
The relative weight of the elements
The sum of the atomic weights of the elements found
in a molecule or compound.
Molecular Weight = 2 + 16 = 18
Equivalent weight is the weight of 1 unit of charge expressed in milligrams
- mineral or organic particles in soil having a diameter less than .001 mm.
- have high surface areas; chemical reactions take place on the colloid surface.
- In most soils, the surfaces of the colloids have a negative (-) charge.
In order to understand the chemistry of a soil you must know what clay minerals are present and their contribution to the negative charge.