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Some elements
of the periodic table
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Co
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history of discovery
1735
Swedish mineralogist
Georg Brandt
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physical properties
hard metal
exists in two versions
melting point of 1494 ° C
ferromagnetic material
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chemical properties
2Co + O2 = 2CoO
Co + Br2 = CoBr2
2Co + N2 = 2CoN
3Co + C = Co3C
Co + 2H2SO4 = CoSO4 + SO2 + 2H2O
2Co + 8CO = Co2(CO)8
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biological function
Vital for the body trace element.
It is a part of vitamin B12 (cobalamin).
It is involved in blood formation, function of the nervous system and liver, enzymatic reactions.
The human need for cobalt 0,007-0,015 mg daily.
In the absence of cobalt akobaltoz develops.
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Ni
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history of discovery
1751
swedish mineralogist
Cronstedt
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physical properties
silver-white metal
does not tarnish in air
Has a face-centered cubic lattice
In its pure form is very plastic and easy to work pressure.
Density (at n. Y.) = 8.902 g / cm ?
Melting point = 1726 K
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chemical properties
2Ni + O2 = 2NiO
3Ni + N2 = Ni3N2
2Ni + B = Ni2B
Ni + 4HNO3 = Ni(NO3)2 + 2NO2 + 2H2O
Ni + CuSO4 = NiSO4 + Cu
Ni + 4CO = Ni(CO)4
Ni + Cl2 = NiCl2
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biological function
It is one of trace elements necessary for the normal development of living organisms.
It takes part in enzymatic reactions in animals and plants.
In the body, it accumulates in animal dead skin tissues, especially in the feathers.
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Hf
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history of discovery
1923
French chemist
Jean Urbain
Danish chemist:
Dirk Coster and
Georg de Hevesy
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physical properties
silvery-white, having a surface with a bright luster is not fading
At ordinary temperatures it has a hexagonal lattice
Density = 13.09 g/cm3 (20 ° C)
refractory metal, its melting temperature = 2222 ° C
One of the rare natural isotopes of hafnium, 174Hf, exhibits a weak alpha activity (half-life of 2.1015 years)
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chemical properties
Hf + 2F2 = HfF4
Other reactions that occur under the influence of very high temperatures and in practice. It also remains unclear their mechanism.
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biological function
not installed
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He
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history of discovery
August 18, 1868
French scientist
Pierre Janssen
October 20, 1868
English astronomer
Norman Lockyer
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physical properties
practically inert chemical element.
nontoxic
is colorless, odorless and tasteless
Under normal conditions - monatomic gas
Its boiling point (T = 4,215 K for 4He) the lowest of all the simple substances
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chemical properties
inert gas
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biological function
At the moment, the biological role is not clear
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you have viewed the presentation of some chemical elements.
Slides prepared for you Kobets TimoPhEy,
Department of Chemistry,
the group “MXO-12"
