Types of inorganic compounds

Objectives To consider the range of different types of inorganic compounds To learn how to name them! Outcomes 1. To be able to list the different types of inorganic compounds and list some of their key features

Main types of inorganic compound 1. Acids 2. Oxo acids; 3. Hydroxides 4. Metal oxides 5. Non metal oxides 6. Binary salts and those containing polyatomic ions 7. Peroxides

Acids These are compounds that dissolve in water to release Hydrogen ions H+ also called protons because a hydrogen ion has lost its one electron and there are no neutrons in the Hydrogen nucleus. Strong acids release high concentrations of hydrogen ions – weak acids release low concentrations of hydrogen ions. Simple acids comprise Hydrogen plus another non/metal such as chlorine (HCl) Such acids are named following these rules Name always starts with hydro The anion name is changed from ide to ic So HCl is hydrochloric acid What would we call HF What would we call HI

Oxoacids These are all acids that contain both a hydrogen ion and an anion containing oxygen. Examples are sulphuric and nitric acid: H2SO4 HNO3 These are formed when the oxides of sulphur and nitrogen dissolve in water. The oxides of sulphur and nitrogen are gases and covalent molecules. They become ions when dissolved. Oxo acids are named differently The main form is named after the other element in the anion (not the oxygen) and the name ends in ic

Oxoacids continued If it has one more oxygen than the normal ic form then it has the prefix per added E.g. Chloric acid is HCLO3 Add another oxygen and you get perchloric acid: HCLO4

Oxo acids continued If there are less oxygens than the ic form then you add the suffix ous E.g. Sulphuric acid is H2SO4 Sulphurous acid is H2SO3 Nitric acid is HNO3 Nitrous acid is …… 2 fewer and you also add the prefix hypo E.g. hypochlorous acid: HClO

Main lab acids HCl Hydrochloric H2SO4 Sulphuric acid HNO3 Nitric acid You must learn these three off by heart – no excuses!

3. Hydroxides These are bases that dissociate into metal and hydroxyl (OH)- ions when dissolved in water; Hydroxyl ions have as you can see a valency of -1. pH of solution is always alkaline (more than 7) Most formed by group 1 and 2 metals, but others can be formed such as Aluminium and Iron (III) hydroxide. Most are highly soluble, whilst some like iron (iii) are not.

Hydroxides continued Strong alkalis are very corrosive of organic tissue; Feel and taste soapy Strong bases e.g. NaOH dissociate almost completely in water: NaOH (s) dissolved in water Na+(aq)+ OH-(aq) Almost no NaOH remains.

Hydroxides continued Weak bases such as ammonia (NH3) do form weak alkalis, but much of the ammonia remains as undissociated molecules rather than accepting a hydrogen ion to become ammonium (NH4)+ (Double arrow shows that reaction is constantly going in both directions. NH3 (g) + H2O (NH4)+(aq) + OH-(aq)

Hydroxides continued Neutralise acids – OH- react with H+ ions in a ratio of 1:1 to produce water. Acid + alkali salt + water (remember this!!) Hydroxides used in soap manufacture, detergents, cleaners, solutions for unblocking drains and antacids

Metal oxides Often known as bases Formed by burning metals in air, or by natural oxidation which results in the corrosion of metals; Most metals react with oxygen to form oxides, though some such as gold do not. Oxygen has a valency of 2 so it is easy to work out the formulae if you know the valency of the metal Oxidation of many metals is also known as corrosion or in the case of iron, rusting!

Work out the formulae of these Lithium oxide Copper (i) oxide Silver (ii) oxide Tin (iv) oxide Beryllium oxide

Non-metal oxides These tend to be gases, e.g. sulphur dioxide, carbon dioxide, and the various nitrous oxides. They are found in exhaust gases and are an important part of air pollution. When dissolved in water they form acids (oxo acids) This leads to acid rain. The strength of the oxo acid depends on how readily they dissociate into their ions. Sulphur dioxide readily dissociates to form sulphuric and sulphurous acids which are very strong acids. Carbon dioxide only slightly dissociates to form carbonic acid which is very weak.

Salts Do not get confused. Table salt is only one of many Salts are made of a metal and a non metal They are of course ionic compounds Those containing simply a metal and one type of non metal as a cation and anion are called binary salts. Those such as sulphates with polyatomic anions containing oxygen are referred to as oxisales in spanish. No direct translation of this has been found by me as yet. (oxisalts?). Do we really need to distinguish?? They have variable solubilities: copper sulphate is very soluble, calcium carbonate (chalk and limestone is only very slightly soluble)

Salts continued If dissolved in water readily conduct an electric current Have high melting points The more reactive the constituent elements, the more stable the salt; In solution a less reactive cation can be replaced by a more reactive one E.g. Copper sulphate + calcium = Calcium sulphate + copper

Salts continued Produced by the reactions of metals and alkalis with acids Metal + acid = Salt + Hydrogen Acid + alkali = Salt + water Acid + carbonate = salt + carbon dioxide + water

Acids and salts Sulphuric acid makes sulphates Nitric acid makes nitrates Carbonic acid makes carbonates Hydrochloric acid makes chlorides Sulphurous acid makes sulphites Nitrous acid makes…………………….. Hydrofluoric acid makes ……………… Chloric acid makes …………………….

Peroxides Have an additional oxygen H2O2 Called hydrogen peroxide Formed in cells during metabolism Strong oxidising agent Breaks down to water and oxygen Write the balanced equation

Your research Find an example of each of these types of compounds which has a use or plays a role, good or bad in our lives. 1. Acids 2. Oxo acids; 3. Hydroxides 4. Metal oxides 5. Non metal oxides 6. Binary salts and those containing polyatomic ions 7. Peroxides Work together in pairs. This will be your P3 exam. Submit to howard@itesm.mx Friday afternoon.

Rubric for team report on types of compounds 1. name an example 2. Give its formula 3. explain it’s use or the harm it causes 4. say how it is formed 5. add any relevant information you can e.g environmental impacts of its production 6. reference information where it is in the text – not just at the end. 7. Use visual information with captions 8. describe chemical reactions with formulae 9. Try to write in perfect English (check each other’s spelling) 10 marks per section. 70 marks in total