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Inorganic Chemistry

Here I will show many inorganic compunds. Inorganic substances are substances without long carbon chains. Inorganic substances are little molecules and not huge molecules. There are less inorganic than organic compounds.

Elements of the periodic table

Alkali metals: The alkali metals are the first group of the periodic table of the elements. These metals are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs) and francium (Fr). They have got one outer electron and the connection to the atomic nucleus is very weak. They are the least noble substances. In the air they react very fast with oxygen and so they are covered in an oxide layer. Alkali metals are kept in liquid hydrocarbons like petroleum. The reactivity grows from lithium to caesium. They react suddenly with water, then they burn or can even explode. Because of the big radius of caesium his outer electron is very free, so caesium reacts so strong with oxygen that it begins to burn in the air. When these metals react with water the product is a caustic solution, like caustic soda solution (NaOH). They are very soft, too.

Alkaline earth metals : The alkaline earth metals are the second group of the periodic table of the elements. These metals are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). These elements have got two outer electrons and so they did not react as strong as the alkali metals, because also can make caustic solutions. These elements are much harder than the alkali metals. Magnesium is an element which do not only burns in oxygen, but in all substances which contain oxygen. So magnesium burns in water, too. Divers use magnesium flares to see something under water.

Boron group: The boron group is the third group of the periodic table of the elements. These elements are boron (B), aluminium (Al), gallium (Ga), Indium (In) and thallium (Tl). Boron is a metalloid and there other four elements are metals. The most used element of this group is aluminium. They elements are reactively. When aluminium is used it is covered in an oxide layer.

Carbon silicon group: The carbon silicon group is the fourth group of the periodic table of the elements. These elements are carbon (C), silicon (Si), germanium (Ge), tin (Sn) and lead (Pb). Carbon is so noble that it is a nonmetal. Silicon and germanium are metalloids and tin and lead are metals. Lead is a very soft metal. Silicon is very often found in the compound silicon dioxide (quartz). Silicon and germanium are very important semiconductor and so they are very important for elektronics.

Pnictogens: The pnictogens are the fifth group of the periodic table of the elements. These elements are nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb) and bismuth (Bi). Nitrogen and phosphorus are nonmetals. Arsenic and antimony are metalloids and bismuth is a metal. 80% of the earth atmosphere are nitrogen, but in molecules (N2).

Chalcogens: The chalcogens are the sixth group of the periodic table of the elements. These elements are oxygen (O), sulfur (S), selenium (Se), tellurium (Te) and polonium (Po). Oxygen and sulfur and nonmetals. Selenium and tellurium are metalloids and polonium is a metal.

Halogens: The halogens are the seventh group of the periodic table of the elements. These elements are fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (At). Fluorine, chlorine, bromine and iodine are nonmetals. Astatine is a metalloid. The halogens only need one electron to reach the noble gas configuration and so they are very reactively. Fluor is the most reactively element of all elements. Many substances (for example wood) begin to burn, because of the contact with fluorine. Fluorine is a colorless gas. The other halogens are very dangerous, because they are very reactively and very corrosive, too. Clorine was used as a strong corrosive poison in the First World War. It is yellow-green. Bromine is a dark liquid at room temperature and like all other halogens a very corrosive substance.

Noble gases: The noble gases are the eigthth group of the periodic table of the elements. These elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). They are all nonmetals and like the name it says they are gases. They have got 8 outer electron (helium: 2 outer electrons) and they nearly do not react at all. They are the most noble elements.

Transition metals: We have not got mentioned the most elements of the periodic table of the elements. These are the transition metals. They metals where the other atomic shells are filled. Famous metals are for example gold (Au), silver (Ag), iron (Fe), copper (Cu), mercury (Hg) and many others. The lanthanoids (rare-earths) and the actionoids belong also to the transition metals. Famous actinoids are the both radioactive elements uranium (U) and plutonium (Pu). More information are on the homepage of nuclear physics.


In this chapter we will see some inorganic acids. When we say hydrochloric acid we connect the formula HCl with it. We have seen before that HCl is hydrogen chloride and a gas. Hydrochloric acid originates when we dissolve HCl in aqueous solutions. In chemistry it is enough to say HCl for hydrochloric acid, because every chemist knows that in reality it is hydrogen chloride which is dissolved in water.

Hydrochloric acid and other hydrogen halides: Hydrochloric acid has got the chemical formula HCl, but dissolved in water. Hydrogen chloride has got a melting point of -114 degrees and a boiling point of -85 degrees. Hydrogen chloride is colorless and has got a strong biting smell. Hydrogen chloride belongs to the hydrogen halides. In aqueous solutions (as an acid) hydrogen chloride is weaker than hydrogen bromide (HBr) and iodine hydrogen (HI), but stronger than hydrogen fluoride (HF). Hydrochloric acid is a very strong acid and so it is corrosive. Hydrochloric acid with a concentration of 37% is called concentrated hydrochloric acid. Concentrated hydrochloric acid smokes in the air, because it is strong satisfied. Hydrogen chloride escapes. Hydrochloric acid is a part of the gastric acid. In the mouth and in the gullet hydrochloric acid can be corrosive. For the skin concentrated hydrochloric acid is corrosive, too. With not noble metals hydrochloric acid reacts very good, because it is very strong. These compounds are called chlorides and are the salts of the hydrochloric acid. One of these is common salt (NaCl). Hydrogen chloride is made of the elements hydrogen and chlorine. HCl also originates in the reaction between common salt (NaCl) and sulfuric acid (H2SO4). For the chemical research and also for the industry hydrochloric acid is a very important substance.

Sulfuric acid: Sulfuric acid has got the chemical formula H2SO4, but dissolved in water. It is a very strong acid and it is colorless and odorless. When we dissolve it in water it is important that the acid had to be into the water and not reversal. Otherwise the acid will squirt, because of a strong heating. Sulfuric acid reacts with not noble metals and with organic materials like paper. It is a double proton acid and so it can dissociate twice. The salts which originate after the first dissociation are called hydrogen sulfates, because the acid residue anion is HSO4-. The salts which originate after the second dissociation are called sulfates, because the acid residue anion is SO42-. Sulfuric acid is used as the electrolyte for lead-acid batteries in cars. For the industry it is very important, too.

Nitric acid and its salts: Nitric acid has got the chemical formula HNO3, but dissolved in water. HNO3 is a colorless liquid. Nitric acid is weaker than hydrochloric acid and sulfuric acid. Nitric acid is corrosive for the skin and the inhalation of nitric acid is corrosive for the body. A mixture of nitric acid and hydrochloric acid is called aqua regia, because it can even dissolve gold. The salts of the nitric acid are called nitrates. High concentrated nitric acid can inflame organic materials like wood. Throught a special burning of ammonia (NH3) nitric acid is made. The industry uses nitric acid as an oxidizing agent. Sodium nitrate (NaNO3) is an important salt of the nitric acid. It is used a fertilizer. Potassium nitrate (KNO3) is explosive. Black powder is a mixture of carbon, sulfur and potassium nitrate.

Carbonic acid and its salts: Carbonic acid has got the chemical formula H2CO3, but dissolved in water. This acid only exists in aqueous solutions. It originates when carbon dioxide (CO2) is dissolved in water. It is a medium acid. The salts which originate after the first dissociation are called hydrogen carbonates and the salts which originate after the second dissociation are called carbonates. Many drinks contain carbonic acid. They have got bubbles and they taste in a special way. Sodium carbonate (Na2CO3) is an important salt of the carbonic acid. It is also called soda. It is hygroscopic. It reacts alkaline and is used to neutralize acids. It is also used for the production of glass and for many other chemicals. Sodium hydrogencarbonate (NaHCO3) is also an important salt of the carbonic acid. It is used as baking-powder. Calcium carbonate (CaCO3) is also an important salt of the carbonic acid. In nature it can be found as calcit, marble and corals.

Phosphoric acid: Phosphoric acid has got the chemical formula H3PO4, but dissolved in water. The formula shows us that it is a triple proton acid. Pure phosphoric acid has got a melting point of 42.3 degrees and so it is solid in room temperature. Phosphoric acid is a medium acid and not dangerous for human beings. The salts which originate after the first dissociation are called dihydrogen phosphates, the salts which originate after the second dissociation are called hydrogen phosphates and the salts which originate after the third dissociation are called phosphates. Phosphoric acid is used to produce fertilizer with phosphorus. Different drinks like coca cola contain phosphoric acid.

Caustic solutions

With caustic solutions it is the same like with acids. A caustic solution has originate when a certain substance is dissovled in an aqueous solution.

Caustic soda solution: Caustic soda solution has got the chemical formula NaOH, but dissolved in water. Not dissolved it is at room temperature a white crystallized powder. Sodium hydroxide also dissolves in alcohols. While dissolving in water it heats. Caustic soda solution is corrosive for the skin. The OH- ion is like in other caustic solutions the important part. Sodium hydroxide dissociates in water, like acids, but caustic solutions always dissociate complete. Caustic solutions are always alkaline and so they are the opposite of acids. Sodium hydroxide is also water-attractively so when the air is damp caustic soda solution can originate. Sodium hydroxide should be kept closed. When we neutralize hydrochloric acid (HCl) with caustic soda solution then sodium chloride (NaCl) and water originate. Technical caustic soda solution is made in an electrolytical reaction of common salt (NaCl) and water. Sodium hydroxide is very important for soaps and other cleaners. Soaps are always of an alkaline character.

Caustic potash solution: Caustic potash solution has got the chemical formula KOH, but dissolved in water. Here we have got again an alkali metal in a compound. Potassium hydroxide and caustic potash solution are very similiar to sodium hydroxide and caustic soda solution. Potassium hydroxide is also solid and white at room temperature. It is water-attractively and so it has to be kept closed. Potassium hydroxide dissolves in alcohols. Caustic potash solution is also very corrosive, so that it should not come in contact with the skin. When we neutralize hydrochloric acid (HCl) with caustic potash solution then potassium chloride (KCl) and water originate. Potassium chloride is like common salt (NaCl) another salt of the hydrochloric acid. Potassium hydroxide is made of potassium chloride in an electrolytical way. It is used as an electrolyte in some accumulators.

Inorganic poisons

Prussic acid: Prussic acid is not important as an acid, because the acid properties are very weak, but it is very toxically. The chemical formula is HCN and so it is called hydrocyan. The important part is the cyanide ion (CN-). Between the carbon atom and the nitrogen atom there is a triple bond. Up to 26 degrees hydrocyan is liquid and then a gas. It is colorless. It smells like bitter almonds. Prussic acid blockades the oxygen transport from the hemoglobin to the web. The consequence is an interior suffocation. So prussic acid is one of he most dangerous poisons. This process happens in a few seconds. Prussic acid can be absorbed throught the skin and it makes it more dangerous. The salts of prussic acids are called cyanides and are very toxically, too. The smell of bitter almonds is caused by prussic acid. In the Second World War prussic acid was used under the name cyclone B in gas chambers in different concentration camp, because it acts so fast. the deadly dose is about 1 mg cyanide ions (CN-) per 1 kg of body weight. The cyanide ion is the strongest inorganic poison. Prussic acid is made of methane (CH4) and ammonia (NH3). It also originates in different burning processes so that they could be very dangerous. It is used for the pest control.

Potassium cyanide and other salts of the prussic acid: Potassium cyanide is a cyanide and the most famous salt of prussic acid. It has got the formula KCN. At room temperature potassium cyanide is a white crystallized powder. 120 mg or more are the deadly dose for a man. KCN can be dissolved in water and the products are prussic acid (HCN) and potassium hydroxide (KOH). It cannot be dissolved well in alcohols. The most acids react with KCN and the product is prussic acid. It is interesting, because in the stomach KCN reacts with the hydrochloric acid from the gastric acid. Prussic acid (HCN) and potassium chloride (KCl) originate. Now the prussic acid can dissociate. So when someone eats potassium cyanide the symptoms of a poisoning need longer than when someone directly takes prussic acid. Because of this reaction it is logical that potassium cyanide acts in the same way that prussic acid. Other alkali metals together with prussic acid forms cyanides, too. For example there are also sodium cyanide (NaCN) and rubidium cyanide (RbCN). Today it is made throught the neutralization of prussic acid (HCN) with potassium hydroxide (KOH). It is used for the cyanide chemistry. Compounds between gold or silver and cyanide originate.

Phosgene: Phosgene has got the chemical formula COCl2. It is a colorless gas and below 7 degrees it is liquid. It is an important chlorine compound used in the First World War, like chlorine. It is dangerous, because it reacts with the water in the lungs to hydrochloric acid (HCl) and carbon dioxide (CO2). This process takes so long that the effect begins after a few hours. Problems with the breathing are the first symptoms. The interior body cauterizes and then a lungs oedema is the consequence. This leads to a suffocation. It is a very dangerous poison. Phosgene is made in the reaction between carbon monoxid (CO) and chlorine (Cl2). Phosgene is used to made different organic compounds.

Ammonia and ammonium salts

Ammonia has got the chemical formula NH3. It has got a melting point of -78 degrees and a boiling point of -33 degrees. In room temperature it is a gas, but with a pressure of 8 bar it becomes liquid. Ammonia is colorless and has got a biting smell. Ammonia can be dissolved in water, but also in many organic liquids (alcohols). Pure ammonia is corrosive and dangerous for health. In water ammonia behaves as a base, because it takes a proton from the water. The NH4+ ion originates. Ammonia dissolved in water is called ammonia water. The chemical industry produces ammonia since 1913 in the company BASF with the Haber-Bosch process. Longer inhalation of ammonia is deadly. For the chemical industry ammonia is a very important substance, because many other substances are made of it. Fertilizer are made of ammonia, but also prussic acid. A famous ammonium salt is ammonium chloride (NH4Cl). It is used in the photography like ammonium bromide (NH4Br). Ammonium chloride is also used as lozenge. Ammonium nitrate (NH4NO3) is an important ammonium salt. It forms white crystals. Today it is also used as fertilizer, but in former times it was a very important explosive.


Rock crystal Amethyst

Quartz is a very interesting substance and so I will describe it in an own chapter. Quartz has got the chemical formula SiO2 and iis called silicon dioxide. I have describe it in the chapter about the bonds that silicon dioxide is a transition between an atomic bond and and ionic bond. The reason is that silicon is a metalloid and oxygen is a nonmetal. Most of the compounds between metals and nonmetals are ionic bonds. Here we have got a metalloid and the bond is very strong polar, but not strong enough that the oxygen could take electrons from the silicon. Ions do not originate. Those substances have got special properties and are similiar to the diamond. Silicon dioxide has got a melting point of 1710 degrees and a boiling point of 2230 degrees. Because of this temperature resistance quartz glass is used to keep very hot materials. The other advantage is the high resistance against acids. All acids can be kept in quartz glass except hydrofluoric acid (HF). Hydrofluoric acid is a hydrogen halide and so it is very similiar to hydrochloric acid (HCl). Silicon dioxide has got a very small coefficient of expansion. This means that it expands very little when the temperature grows. The advantage is that a quartz glass would not break like normal glass when the temperature grows. Clear quartz is colorless and transparent. It is an interesting mineral, because it has got very nice crystals. They have got always six sides and then there is a bend and the six sides form a spike. Mineralogical there a many variants of silicon dioxide which you can see on the homepage of minerals. Clear quartz is rock crystal. There are also quartzes with other substances like amethyst (violet), citrine (yellow), smoke quartz (brown), milk quartz (not transparent white). The three first minerals are tranparent. There also other variants which do not grow symmetrical, because of the other substances. They are amorph.

Author and Webmaster: Lukas Czarnecki

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Last Update: 15.12.2004