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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: 901
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