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Basic
Chemical Concepts
A.
Matter
Matter
. Any substance which has mass and occupies space. All physical objects are composed of matter in the form of atoms, which are composed of protons, neutrons, and electrons. It is the material of which the universe is composed and exists
in three forms: solids, liquids, gases.
B.
Components of Matter
1.
Element
- A substance which cannot be decomposed by ordinary chemical means.
There are 103 elements now known that singly or in combination constitute
all matter and are described in the periodic
table.
Ex.
N, P, K, Au, Ag, H, O
2.
Atom
- Smallest particle of an element that maintains its chemical identity.
3.
A compound
is a complex substance that can be decomposed by chemical methods
into simpler substances.
4.
Molecule - A chemical
combination of two or more atoms which form a specific chemical
substance. To break up the molecule into its constituent atoms is
to change its character.
HOH
NaCl
C.
Atomic weight
The
relative weight of one atom of an element compared with the
weight of one atom of carbon (12) or one atom of oxygen (16).
O
=16, H =1, N = 14, Au = 197
Also
the sum of protons and neutrons in the nucleus
D.
Molecular
weight
The sum of the atomic weights of all the atoms of any one molecule
H2O
1+1+16 = 18
KCl
39+35 = 74
E.
Equivalent
weight
The atomic weight of an element divided by the valence it assumes
in a chemical compound.
Atomic
weight divided by the valence= equivalent weight
equivalent weight of K = 39/1 = 39, Ca = 40/2 =20
F.
Ions
An ion is an atom or group of atoms that have a net electric
charge
Na
loses an electron Na+
Cl
gains an electron Cl-
a.
Cation - A positively charged atom or group of atoms
NH4+
, K+, Al+++, Ca++
b.
Anion - A negatively charged atom or group of atoms
NO3-,
H2PO4- , HPO4=,
Cl-, SO4=
Ions
with the same charge repel while opposite charges attract.
Ca++
repels H+
Ca++
attracts SO=4
Soil
Colloids - (clay and organic matter) are negatively charged;
therefore they attract cations.
H+
Mg++
Ca++
Al++
K+
Anions
such as NO- 3, SO=4,
and Cl- move freely in the soil. they are not retained
by soil colloids.
Phosphate
is a special case anion. It does not move freely in the soil
because it forms insoluble compounds with iron and aluminum
in acid soils and calcium in high pH soils.
(C) HOPKiNS (name) CaFe Managed By Mine CuZins, Mo and Claude
C H O P K N S CaFe Mg B Mn CuZn Mo Cl
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