NOTE:The letter R is used to represent an arbitrary radical.
See also the Geology Glossary.
Acid - 1) A substance with a sour taste.
2) A substance that yields hydrogen ions when dissolved in water (compare with base).
3) A compound containing a carboxyl group (-COOH).
Acyl - A radical having the general formula RCO-, derived from an organic acid by the removal of the OH group.
Alcohol - 1) A compound containing a hydroxyl group (-OH). 2) The common name
of ethyl alcohol or grain alcohol (CH3CH2OH)
R-OH
Aldehyde - A compound containing an aldehyde group (-CHO).
Aliphatic - An organic compound that does not contain ring structures.
Alkane - A saturated carbon compound with the general formula CnH2n+2.
The first five alkanes (n=1 to 5) are:
methane, ethane, propane, butane, and pentane.
CH3-CH2-CH2-CH3
Butane
Alkene - A compound consisting of only carbon and hydrogen, that contains at least one carbon-carbon double bond
and is thereby unsaturated. Example: Ethylene (CH2=CH2)
Alkyl - A molecular fragment of an alkane from which one hydrogen atom has been removed,
and has the general formula CnH2n+1.
Examples: methyl (-CH3), ethyl (-CH2CH3).
Alkyne - A compound that consists of only carbon and hydrogen containing at least one carbon-carbon triple bond.
Amide - An organic compound containing a carbonyl group bound to nitrogen: R-(C=O)NH2.
Amine - A compound containing an amino group (-NH2).
R-NH2
Amino Acid - A compound with amino and carboxyl groups that is a constituent of
peptides and proteins.
Aromatic Compound - An organic molecule containing at least one benzene ring.
Benzene
Atom - The smallest component of an element that still has properties of the element,
consisting of a positively charged nucleus, and surrounded by a charged cloud of electrons.
The nucleus contains protons and may contain neutrons. (See Periodic Table, below)
Examples of atoms.
Atomic Number - The number of protons in a nucleus. It determines the chemical properties
of an element.
Atomic Weight - The atomic mass of an atom relative to 1/12 of the mass of
the Carbon-12 isotope.
Base - A substance that accepts hydrogen ions when dissolved in water (compare with acid).
Bond - The attraction of atoms to each other through sharing or exchanging electrons.
Carbohydrate - A term used for sugars and sugar derivatives that contain only carbon, hydrogen,
and oxygen, usually in the ratio 1:2:1
Halogen - The elements of Group 17 (VIIA) of the periodic table: fluorine (F), chlorine (Cl), bromine (Br),
iodine (I), and astatine (At).
Heterocyclic Compound - A compound with a ring that contains non-carbon atoms.
Purine - A heterocyclic compound
Hydrocarbon - Any organic compound, such as benzene and methane, that contain only carbon and
hydrogen.
Hydroxyl Group - A chemical group containing one hydrogen and one oxygen (-OH)
Inorganic compound - A chemical compound that does not contain carbon.
Ion - An electrically charged atom or molecule obtained by the gain or loss of electrons.
Ionic bond or electrovalent bond, is an electrical attraction between two oppositely charged
atoms or groups of atoms. Compare with covalent bond.
Isotope - An atom having the same number of protons but a
different number of neutrons in its nucleus.
Ketone - A compound containing a carbonyl group (C=O).
Line Formula - A chemical formula that shows atomic attachments expressed in a linear form, e.g.,
RCH(NH2)COOH. Compare with structural formula and molecular formula.
Methyl - The organic group derived from methane CH3-. See Alkyl.
Molecular Formula - A summary of the number of specific elements in a chemical compound
that does not specify how the atoms are the atoms are attached. Example: Benzene has the molecular
formula C6H6.
Compare with the structural formula for benzene under Aromatic Compound.
Molecule - The smallest particle of a substance that retains the chemical and physical
properties of the substance and is composed of two or more atoms.
Neutron - A non-charged nuclear particle with the same mass as the proton.
Nitrate - The radical -NO3, or a compound containing it.
Proton - A component of an atomic nucleus with a mass defined as 1 and a charge of +1.
Organic compound - A chemical compound containing carbon chemically bound to hydrogen.
Other elements such as O, N, halogens, or S may be present.
Peptide - A compound consisting of 2 or more amino acids.
Peptide bond - A peptide bond (amide bond) is a chemical bond formed between two
molecules when the carboxyl group (-COOH) of one molecule reacts with the
amine group (-NH2) of the other.
Periodic Table - An arrangement of the elements according to their atomic numbers so that
elements with similar properties are in the same column. The first periodic table was published
by Dmitri Mendeleev in 1869.
The symbols of some elements are derived from their Latin names (in parentheses).
Chemical element
Symbol
Atomic number
Actinium
Ac
89
Aluminum
Al
13
Americium
Am
95
Antimony (Stibium)
Sb
51
Argon
Ar
18
Arsenic
As
33
Astatine
At
85
Barium
Ba
56
Berkelium
Bk
97
Beryllium
Be
4
Bismuth
Bi
83
Bohrium
Bh
107
Boron
B
5
Bromine
Br
35
Cadmium
Cd
48
Calcium
Ca
20
Californium
Cf
98
Carbon
C
6
Cerium
Ce
58
Cesium
Cs
55
Chlorine
Cl
17
Chromium
Cr
24
Cobalt
Co
27
Copper (Cuprum)
Cu
29
Curium
Cm
96
Darmstadtium
Ds
110
Dubnium
Db
105
Dysprosium
Dy
66
Einsteinium
Es
99
Erbium
Er
68
Europium
Eu
63
Fermium
Fm
100
Fluorine
F
9
Francium
Fr
87
Gadolinium
Gd
64
Gallium
Ga
31
Germanium
Ge
32
Gold (Aurum)
Au
79
Hafnium
Hf
72
Hassium
Hs
108
Helium
He
2
Holmium
Ho
67
Hydrogen
H
1
Indium
In
49
Iodine
I
53
Iridium
Ir
77
Iron (Ferrum)
Fe
26
Krypton
Kr
36
Lanthanum
La
57
Lawrencium
Lr
103
Lead (Plumbum)
Pb
82
Lithium
Li
3
Lutetium
Lu
71
Magnesium
Mg
12
Manganese
Mn
25
Meitnerium
Mt
109
Mendelevium
Md
101
Chemical element
Symbol
Atomic number
Mercury (Hydrargyrum)
Hg
80
Molybdenum
Mo
42
Neodymium
Nd
60
Neon
Ne
10
Neptunium
Np
93
Nickel
Ni
28
Niobium
Nb
41
Nitrogen
N
7
Nobelium
No
102
Osmium
Os
76
Oxygen
O
8
Palladium
Pd
46
Phosphorus
P
15
Platinum
Pt
78
Plutonium
Pu
94
Polonium
Po
84
Potassium (Kalium)
K
19
Praseodymium
Pr
59
Promethium
Pm
61
Protactinium
Pa
91
Radium
Ra
88
Radon
Rn
86
Rhenium
Re
75
Rhodium
Rh
45
Rubidium
Rb
37
Ruthenium
Ru
44
Rutherfordium
Rf
104
Samarium
Sm
62
Scandium
Sc
21
Seaborgium
Sg
106
Selenium
Se
34
Silicon
Si
14
Silver (Argentum)
Ag
47
Sodium (Natrium)
Na
11
Strontium
Sr
38
Sulfur
S
16
Tantalum
Ta
73
Technetium
Tc
43
Tellurium
Te
52
Terbium
Tb
65
Thallium
Tl
81
Thorium
Th
90
Thulium
Tm
69
Tin (Stannum)
Sn
50
Titanium
Ti
22
Tungsten (Wolfram)
W
74
Ununbium
Uub
112
Ununtrium
Uut
113
Unununium
Uuu
111
Uranium
U
92
Vanadium
V
23
Xenon
Xe
54
Ytterbium
Yb
70
Yttrium
Y
39
Zinc
Zn
30
Zirconium
Zr
40
Phenyl - A molecular group consisting of a benzene ring where one or more hydrogens have been replaced
by other atoms or radicals. See Aromatic Compound.
Protein - A compound consisting of 50 or more amino acids.
Saturated Compound - An organic compound, such as butane, that contains only single
carbon-to-carbon bonds. The name derives from the fact that the compound cannot
bind to additional hydrogen atoms, and is, therefore, "saturated" with hydrogen.
CH3-CH2-CH2-CH3
Butane
Structural Formula - A chemical structure representation that shows all the atomic attachments.
Example: see Amino Acid.
Sugar - See carbohydrate
Transition element - Any element belonging to one of three series of elements with atomic numbers between 21 and 30, 39 and 48, and 57 and 80. They are characterized by multiple valences, colored compounds, and the ability to form stable complex ions.
Triglyceride - 1) Fat. 2) A compound consisting of one molecule of glycerol and three fatty acids.
Also called triacylglycerol.
Unsaturated Compound - An organic compound that contains double or triple
carbon-to-carbon bonds, and can theoretically bind to additional hydrogen atoms.
CH2=CH-CH2-CH3
1-Butene
Valence - The combining capacity of an atom or radical determined by the number of electrons
that it will lose, add, or share when it reacts with other atoms.