Objectives• Know how to name compounds• Know how to write formulas• Know how to work out how many of each atom there are in a compound, based on a formula
Atoms in compoundsCompounds contain two or moredifferent types of atom.The compound, water,exists as molecules.Each water moleculeconsists of twohydrogen atomsjoined to one oxygenatom.
Making a compound – water Water is produced from the chemical reaction between hydrogen and oxygen. hydrogen + oxygen water H H + O O H H Two hydrogen molecules react with one oxygen molecule to produce two molecules of water. Why does water have different properties to its elements?
Properties of a compound – carbon dioxideA compound has different properties to the elementsfrom which it is made because the atoms are joineddifferently. carbon + oxygen carbon dioxide + Black solid Colourless gas in Colourless gas usedused as fuel. which many in fizzy drinks and substances fire extinguishers. burn. C + O O
Copper Element Mercury ElementAluminium Element Oxygen Element
Water (H2O) Carbon dioxide (CO2)Iron sulphide (FeS)
Naming simple compoundsTo name simple compounds of metals and non-metals:1. Write down the name of the metal.2. Write down the name of the non-metal, changing the ending of the word to “-ide”.What is the name of the compound made when thefollowing elements combine? magnesium and oxygen magnesium oxide sodium and chlorine sodium chloride oxygen and iron iron oxide
Naming simple compoundsWhat is the name of each compound formed by thesemetal and non-metal elements?Element 1 Element2 Name of compoundiron sulphur iron sulphidemagnesium nitrogen magnesium nitridesodium chlorine sodium chloridetin oxygen tin oxidealuminium bromine aluminium bromidenickel iodine nickel iodidezinc sulphur zinc sulphidelithium nitrogen lithium nitride
Naming further compounds Many compounds contain more than two elements. For compounds containing two elements plus oxygen, the ending of the other non-metal usually changes to “ - ate”.Element 1 Element 2 Element 3 Name of compoundnickel sulphur oxygen nickel sulphatemagnesium nitrogen oxygen magnesium nitratesodium nitrogen oxygen sodium nitratecopper sulphur oxygen copper sulphatealuminium bromine oxygen aluminium bromate
Composition of compoundsA compound contains atoms from different elementsthat are chemically joined together.A compound always contains a particular amount ofeach element. It has a fixed composition.Compound names can get quite long and complicated,so the symbols of the elements are used as ashorthand.The symbols of the elements in a compound arecombined to give the formula of the compound.What is the formula ofcarbon dioxide?
Writing a formulaA formula uses the symbols of the elements in acompound.When there is more than one atom of each element, thenumber is always written after the symbol.carbon dioxide carbon atom = 1 oxygen atoms = 2 formula = CO2 water hydrogen atoms = 2 oxygen atom = 1 formula = H2OThe formula shows the ratio of atoms in a compound.
What is the formula? What is the formula of each of these compounds? (In a formula put the metal first as when naming a compound.)1. Titanium oxide For every titanium atom there are two oxygen atoms. Formula = TiO 22. Lithium oxide For every two lithium atoms there is one oxygen atom. Formula = Li O 23. Aluminium chloride For every aluminium atom there are three chlorine atoms Formula = AlCl 3
What is the formula? What is the formula of each of these compounds? (In a formula put the metal first as when naming a compound.)1. Silicon chloride For every silicon atom there are four chlorine atoms. Formula = SiCl 42. Manganese oxide For every manganese atom there are two oxygen atoms. Formula = MnO 23. Aluminium oxide For every two aluminium atoms there are three oxygen atoms. Formula = Al O 2 3