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Portal:Chemistry

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The Chemistry Portal

Colourful solutions in test-tubes.
Welcome to the chemistry portal. Chemistry is a branch of science. Modern chemistry focuses on the study of elements of the world and the bonds between elements. Chemistry also deals with composition, structure, and properties of substances and the transformations that they undergo. In the study of matter, chemistry also investigates its interactions with energy and itself. Because of the diversity of matter, which is mostly in the form of compounds, chemists often study how atoms of different chemical elements interact to form molecules, and how molecules interact with each other.


Featured article - Selected picture - News - Selected biography - - - - - Periodic Table - Resources - - - - -

Featured article

Coffee beans; a coffee bean contains between 0.8 - 2.5% caffeine.
Caffeine is a xanthine alkaloid compound that acts as a stimulant in humans. Caffeine is sometimes called guaranine when found in guarana, mateine when found in mate, and theine when found in tea. It is found in the leaves and beans of the coffee plant, in tea, yerba mate, and guarana berries, and in small quantities in cocoa, the kola nut and the Yaupon Holly. Overall, caffeine is found in the beans, leaves, and fruit of over 60 plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding upon them.

Caffeine is a central nervous system (CNS) stimulant, having the effect of temporarily warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, soft drinks and energy drinks enjoy great popularity: caffeine is the world's most widely consumed psychoactive substance. In North America, 90% of adults consume caffeine daily.

Many natural sources of caffeine also contain widely varying mixtures of other xanthine alkaloids, including the cardiac stimulants theophylline and theobromine and other substances such as tannins.




Selected biography

Amedeo Avogadro
Amedeo Avogadro (1776-1856) was an Italian chemist, most noted for his contributions to the theory of molarity and molecular mass. Avogadro's law implies that the relationship occurring between the weights of same volumes of different gases (at the same temperature and pressure) corresponds to the relationship between respective molecular weights. Hence, relative molecular masses can be calculated from the masses of gas samples. One of the most important contributions of Avogadro's work was clearly distinguishing atoms from molecules, admitting that simple particles too could be composed of molecules, and that these are composed of atoms.


Selected picture

GC oven

Gas chromatography is an important type of chromatography used in chemical analysis. A volatile substance or mixture is injected and carried down a column (the coil shown) to a detector, which records the amount and the time on the column for each component. An oven (shown here with the door open) maintains the column at a desired temperature.

Periodic Table

Periodic table
Group → 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
↓  Period
1 1
H
2
He
2 3
Li
4
Be
5
B
6
C
7
N
8
O
9
F
10
Ne
3 11
Na
12
Mg
13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
4 19
K
20
Ca
21
Sc
22
Ti
23
V
24
Cr
25
Mn
26
Fe
27
Co
28
Ni
29
Cu
30
Zn
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
5 37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
6 55
Cs
56
Ba
*
72
Hf
73
Ta
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
7 87
Fr
88
Ra
**
104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
111
Rg
112
Cn
113
Uut
114
Fl
115
Uup
116
Lv
117
Uus
118
Uuo

Lanthanides 57
La
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
** Actinides 89
Ac
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr

This is an 18-column periodic table layout, which has come to be referred to as the common or standard form, on account of its popularity. It is also sometimes referred to as the long form, in comparison to the short form or Mendeleev-style, which omits groups 3–12 by placing their elements into the main groups. The wide periodic table incorporates the lanthanides and the actinides, rather than separating them from the main body of the table in order to save space. The extended periodic table adds the 8th and 9th periods, including the superactinides.

Categories and subcategories in the metal–nonmetal range

Metal Metalloid Nonmetal Unknown
chemical
properties
Alkali
metal
Alkaline
earth metal
Inner transition metal Transition
metal
Post-transition
metal
Other
nonmetal
Halogen Noble
gas
Lanthanide Actinide
Colour of the atomic number shows state of matter
(at standard conditions: 0 °C and 1 atm):
black=Solid green=Liquid red=Gas grey=Unknown
Border shows natural occurrence:
 
Primordial From decay Synthetic



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