Periodic table of elements

Some elements of the periodic table

Co

1735 Swedish mineralogist Georg Brandt

history of discovery

physical properties

hard metal exists in two versions melting point of 1494 ° C ferromagnetic material

chemical properties

2Co + O2 = 2CoO

Co + Br2 = CoBr2

2Co + N2 = 2CoN

3Co + C = Co3C

2Co + 8CO = Co2(CO)8

Co + 2H2SO4 = CoSO4 + SO2 + 2H2O

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.

Ni

1751 swedish mineralogist Cronstedt

history of discovery

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

chemical properties

2Ni + O2 = 2NiO

Ni + Cl2 = NiCl2

3Ni + N2 = Ni3N2

2Ni + B = Ni2B

Ni + 4HNO3 = Ni(NO3)2 + 2NO2 + 2H2O

Ni + CuSO4 = NiSO4 + Cu

Ni + 4CO = Ni(CO)4

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.

Hf

history of discovery

1923 French chemist Jean Urbain Danish chemist: Dirk Coster and Georg de Hevesy

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)

chemical properties

Other reactions that occur under the influence of very high temperatures and in practice. It also remains unclear their mechanism.

Hf + 2F2 = HfF4

not installed

biological function

He

history of discovery

August 18, 1868 French scientist Pierre Janssen

October 20, 1868 English astronomer Norman Lockyer

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

inert gas

chemical properties

biological function

At the moment, the biological role is not clear

you have viewed the presentation of some chemical elements

Slides prepared for you Kobets TimoPhEy, Department of Chemistry, the group “MXO-12"