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Other bioactive metals

 

Near 75% of all known chemical elements are metals. Among them there is a series of biologically active macro- and micronutrients (see Table 19).

Table 19. Characteristics of main bioactive metals

Element Period Group Possible Oxidation numbers Chemical properties
Mg 2A 0, +2 Weak amphoteric metal
K 1A 0, +1 Typical alkali metal
Ca 2A 0, +2 Alkali-Earth Metal
Mn 7B 0, +2, +3, +4, +5, +7 Transition metal
Fe 8B 0, +2, +3, +6 Transition metal
Co 8B 0, +2, +3, +6 Transition metal
Cu 1B 0, +1, +2 Transition metal
Zn 2B 0, +2 Transition metal
Al 3A 0, +1, +3 Amphoteric metal

 

All bioactive metals depending on its function for plant, animals or human body may be divided into macro-, micronutrients and toxicants (see Table 20).

 

Table 20. Characteristic of biological function

Element Biological function
Mg Included in Chlorophilium
K Macronutrient for plant nutrition, needed for cell water balance and transparency of membranes
Ca Macronutrient for plant and human nutrition, takes part in synthesis of proteins
Mn Micronutrient, takes part in Redox processes. In excess - toxicant
Fe Micronutrient, needed for processes of breathing and photosynthesis; includes in hemoglobin
Co Micronutrient, included coferments (for example Vitamin B12 - cobalt ammine). In excess - toxicant
Cu Irreplaceable micronutrient. In excess - toxicant
Zn Micronutrient. In excess - toxicant

It is important to know the principles of interaction of metals with different types of acids (see Table 21).

 

Table 21. Interaction acids-oxidizing agents with metals

Formula of acid Metals Notes
Active: The Alkali, The Alkali-Earth, Mg, Zn Heavy with low activity
Scheme of products
H2SO4 (conc.) Sulfate + S + H2O or Sulfate + H2S + H2O Sulfate + SO2 + H2O Fe is immunized by acid
HNO3 (conc.) Nitrate + N2O + H2O Nitrate + NO2 + H2O Not reacts with Au, Pt, Rh, Ir, Ti, Ta; Al, Fe, Co, Ni, Cr are immunized by acid
HNO3 (diluted) Nitrate + N2 + H2O or Nitrate + NH4NO3+ H2O Nitrate + NO + H2O Fe and Sn forms NH4NO3

 

PRACTICE PROBLEMS

1. Characterize general features of metals atoms.

2. Draw the diagrams of electron redistribution and put the coefficients in the equations of the following reactions and characterize metal properties in these reactions:

Ca + H2O →

Mn + H2SO4 (conc.) →

Zn + CuSO4 →

Al + Fe2O3 →

 

LABORATORY TRAINING

 

Experiment 1. Replacing of metals

Put into two test tubes 5-6 drops of CuSO4 and Pb (CH3COO) 2 solutions and add in each tube one granule of free Zinc. 5-10 min. later register how color of Zinc granule is changed. Write the reactions.

 

Experiment 2. Qualitative test of K+ in salts or fertilizers

Fill test-tube with 3-4 drops of Potassium salt solution and add 2-3 drops of Na3[Co(NO2)6]. Form yellow precipitate NaK2[Co(NO2)6]. Write the reactions of precipitate formation.

 

Experiment 3.Change of Calcium Phosphates solubility

Add 2-3 drops of Na2HPO4 solution to 1-2 drops of CaCl2 Solution. Why was precipitate formed?

Add by drops Solution of Phosphorus acid to precipitate until to total dissolving. Write the reactions of precipitate formation and dissolving.

 

Experiment 4. Oxidizing property of Cu+2 ions

Add 2-3 drops of KI solution to 3-4 drops of CuSO4 solution. Observe formation of CuI precipitate and Iodine I2 isolation. Write the reaction.

 

 

 

Date: 2015-01-12; view: 747

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