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Знаки + или - стоящие в левом верхнем углу, обозначают положительную и отрицательную валентность иона.
Пример: H+ a) hydrogen ion
b) univalent positive hydrogen ion
Сu2+ divalent positive cuprum ion
Al3+ trivalent positive aluminum ion
Cl- a) negative chlorine ion
b) negative univalent chlorine ion
Цифра перед названием элемента обозначаeт число молекул.
Примеры:
C + O2 → CO2
1 atom of carbon reacts with 1 two-atom molecule of oxygen and produces 1 molecule of carbon dioxide.
2H2 + O2 → 2H2O
a) Two molecules of H two plus O two give two molecules of H two O.
b) Two two-atom molecules of hydrogen react with 1 two-atom molecule of oxygen and produce two molecules of water.
N2 + 3H2 ↔ 2NH3
a) N two plus three molecules of H two form and are formed from two molecules of NH three
b) 1 two-atom molecule of nitrogen plus three two-atom molecules of hydrogen form and are formed from two molecules of ammonia.
Na2CO3 + CaSO4 → Na2SO4 + CaCO3
a) Na two CO three plus CaSO four form Na two SO four plus CaCO three
b) The sodium (Na) and the calcium (Ca) switch
c) The sodium combines with the sulphate radical (SO4), forming sodium sulphate (Na2SO4) which dissolves in water.
d) The calcium сombines with the carbonate radical (CO3), forming calcium carbonate (CaCO3).
e) Calcium carbonate does not dissolve in water, and so settles to the bottom of the solution.
Practical class 3.
Theme: Classification of inorganic substances. Binary compounds.
INORGANIC SUBSTANCES
| SIMPLE | |||||
| Metals | Non-metals | COMPLEX | |||
| (Cu, Na, Al, Fe) | (S, Cl, C, As) |
| Oxides | Bases | Acids | Salts |
| Oxides - complex substances, consisting from two elements, one of which oxygen. | Bases - complex substances, in which atoms of metals bonded with one or several hydroxyls groups (according to electrolytic dissociation theory bases - complex substances, which under the dissociating in water solution are formed metal cations (or NH4+) and hydroxide anions OH-). | Acids - complex substances, consisting from hydrogen atoms and acid radical (according to electrolytic dissociation theory: acids - electrolytes, which under the dissociating form only H+ in the capacity of cations). | Salts - complex substances, which consist from atoms of metal and acid residuals. This the most multiple class of inorganic compounds. |
OXIDES
| Salts-forming | Non-salts forming |
| CO, NO, N2O |
| Basic | Amphoteric | Acid |
| It is a metal oxides in which metals display low oxidation number +1, +2 Na2O, MgO, CuO | (for metals with oxidation number +3, +4). As a hydrates it corresponding amphoteric hydroxide ZnO, Al2O3, Cr2O3, SnO2 | It is oxides of nonmetals and metals with oxidation number from +5 to +7. SO2, SO3, P2O5, Mn2O7, CrO3 |
Basic, amphoteric- corresponding bases; amphoteric, acid- corresponding acids.
BASES
| Alkalies (soluble in water) | Amphoteric | Hydroxides (insoluble in water) |
| Show also properties of weak acids. |
ACIDS
| On composition | On hydrogen atoms number, which capable to substituted on metal |
| Oxygenless | Oxoacids (containing oxygen) | Monobasic (monoprotic) | Dibasic (diprotic) | Tribasic (triprotic) | |
| HCl, HBr, HI, H2S, HCN | HNO3, H2SO4, HClO4, H3PO4 | HCl, HNO3, HI, HClO3 (Those having one acidic proton) | H2SO4, H2SO3 H2SiO3 | H3PO4 |
On the basis of strengths or capacity to donate hydrogen ions, acids can be described as:
SALTS
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