Naming Compounds When a compound contains only two elements, change the ending of the second element to –IDE Example: sodium + chlorine sodium chloride
Name the compounds formed in the following reactions 1.magnesium + oxygen 2.lithium + bromine 3.zinc + sulphur 4.copper + fluorine 5.potassium + nitrogen magnesium oxide lithium bromide zinc sulphide copper fluoride potassium nitride
When a compound contains three or more elements and one of them is oxygen, the name of the compound ends in –ATE Example: copper + sulphur + oxygen copper sulphate
Name the compounds formed in the following reactions 1.magnesium + nitrogen + oxygen 2.lithium + sulphur + oxygen 3.zinc + carbon + oxygen magnesium nitrate lithium sulphate zinc carbonate
Writing Chemical Reactions – Word Equations and Balanced Symbol Equations When writing out chemical reactions, we always write the reactants on the left hand side and the products on the right We separate the reactants and products by an →, never an =
Example Magnesium was reacted with hydrochloric acid and the salt magnesium chloride and hydrogen gas were produced. magnesium + hydrochloric acid → magnesium chloride + hydrogen
Write word equations for the following reactions 1.Silver nitrate reacts with iron to produce iron nitrate and silver. 2.Fluorine was mixed with potassium iodide and potassium fluoride and iodine were formed. 3.Sodium was placed in water and sodium hydroxide and hydrogen gas were made. Make a list of all the elements and all the compounds mentioned in the above reactions.
The Numbers in a Symbol Equation CH 4 + 2O 2 → CO 2 + 2H 2 O Numbers before a formula show how many molecules of that substance react or are produced Numbers after symbols show how many atoms of that element the molecule contains Why is oxygen O 2 ? Because it is diatomic – exists as 2 atoms bonded together So does: H, Br, F, I, N, Cl
Some Examples 1.Consider the following reaction: 2Na + Cl 2 → 2NaCl a)How many molecules in total are reacting? b)How many molecules in total are produced? c)How many atoms of chlorine are reacting?
2. Consider the following reaction: 2Na + 2H 2 O → 2NaOH + H 2 a)How many molecules in total are reacting? b)How many molecules in total are produced? c)How many atoms of sodium are reacting? d)How many atoms of hydrogen are produced?
Level 7 – Balancing Equations The number of atoms on either side of the equation must be equal
Balancing Equations – The Steps Step 1:Write down the word equation. Step 2:Replace words with the chemical formula. Step 3: Check that there are equal numbers of each type of atom on both sides of the equation. If not, then balance the equation by using more than one. 2 MgO 2 MgO 2 Mg+O 2 Oxygen doesn’t balance. Need 2 MgO and so need 2 Mg MgO MgO Mg+O 2 magnesium oxide magnesium oxide magnesium + oxygen ProductsReactants
ReactantsProducts sodium + water hydrogen + sodium hydroxide + + + + Na H2OH2OH2OH2O H2H2H2H2 NaOH 2 Na 2H2O2H2O2H2O2H2O 2 NaOH H2H2H2H2 Hydrogen doesn’t balance. Use 2 H 2 O, NaOH, 2Na Remember: You should never change a formula when balancing a chemical equation. You can only put numbers in front of a formula
Your turn… Balance the following equations: a) H 2 + F 2 → HF b) Ca + O 2 → CaO c) NaNO 3 → NaNO 2 + O 2 d) N 2 + H 2 → NH 3
Quick Plenary Match up the reactants with the products to form a correct chemical equation Fe + S → Al + O 2 → H 2 + O 2 → Mg + H 2 O → PbS + O 2 → Al 2 O 3 MgO + H 2 PbO + SO 2 FeS H 2 O Can you balance these equations?