The vast majority of inorganic substances in nature can be classified into four categories: oxides, acids, bases and salts. Inorganic substances in organisms mainly include water and some inorganic ions, such as Na+, K+, Ca2+, Mg2+, Cl-, SO42-, etc. Human tissue contains almost all kinds of elements that exist in nature. Except carbon, hydrogen, oxygen and nitrogen, which mainly exist in the form of organic compounds, the rest are collectively referred to as inorganic substances (minerals or ash). Therefore, the inorganic matter in the human body is mainly composed of water and inorganic salts, and water can be classified into: bound water and free water, bound water is an important component of cell structure, free water is a good solvent and transport material, Participate in chemical reactions. Inorganic salts can be divided into: ions and compounds. Ions can maintain the normal life activities of cells, and compounds are important components of intracellular compounds.
1. Oxide
Composed of two elements, one of which is a compound of oxygen. Substances that react with oxygen are called oxides. According to different chemical properties, oxides can be divided into two categories: acidic oxides and basic oxides.
Acidic oxide: An oxide that can react with water to form an acid or react with a base to form a salt. Such as sulfur trioxide, phosphorus pentoxide, carbon dioxide, etc. Most of the non-metallic oxides are acidic oxides.
Basic oxides: oxides that can react with acids to form salt and water, and the products can only contain salt and water, and no other substances can be produced. Basic oxides include active metal oxides and other metal suboxides, such as CaO, BaO and CrO, MnO.
2. Inorganic acid
A general term for a class of compounds that can ionize to generate H in aqueous solution, as opposed to bases. When hydrochloric acid, sulfuric acid, and nitric acid are ionized in aqueous solution, although the anions (acid radicals) produced are different, the cations (H+) produced are the same, so they have common properties, such as having a sour taste; being able to dissolve Many metals; can turn blue litmus paper red, etc.
Narrow definition: a compound (such as sulfuric acid) in which all cations ionized in aqueous solution are hydrogen ions. Most of these substances are easily soluble in water, and a small part, such as silicic acid, is difficult to dissolve in water. Aqueous solutions of acids are generally conductive. Some acids exist in the form of molecules in water and are not conductive; some acids are dissociated into positive and negative ions in water and can conduct electricity.
Broader definition: acid can provide protons in the reaction, and acid is defined as the acceptor of electron pairs, and the scope is more extensive. Acids can neutralize bases to produce water and salts.
3. Alkali
Substances that taste bitter and can change the color of specific indicators (such as turning litmus blue, phenolphthalein red, etc.), with a pH value greater than 7. The anions ionized in aqueous solution are all hydroxide ions, which react with acid to form salt and water. Typical alkalis are amines (including ammonia), caustic soda (sodium hydroxide), slaked lime (calcium hydroxide), etc. The broader concept of a base refers to a substance that donates electrons, or accepts a proton.
4. Salt
The product of acid and alkali neutralization, composed of metal ions (including ammonium ions) and acid ions. Salt in chemistry is divided into three categories, normal salt: composed of metal ions (including ammonium ions) and non-metal ions alone; acid salt: composed of metal ions (including ammonium ions), hydrogen ions and non-metal ions; basic Salt: Consists of metal ions (including ammonium ions), hydroxide ions, and nonmetal ions. Salt is an important source material in the chemical industry. It can be made into chlorine gas, sodium metal, soda ash (sodium carbonate), heavy alkali (sodium bicarbonate, baking soda), caustic soda (caustic soda, sodium hydroxide) and hydrochloric acid.
