Write down the formulae for these: a)Iron (II) Sulfate b)Magnesium Oxide c)Silver Carbonate d)Sodium Phosphate e)Copper Hydroxide f)Aluminium Hydroxide g)Barium Nitrate

1.Which of these are “cations”? 2.Which of these are “anions”? 3.Which of these are “polyatomic ions”? Chloride Cl - Sulfate SO 4 2- Zinc Zn 2+ Sodium Na + Carbonate CO 3 2- Hydroxide OH - Hydrogen H + NitrateNO 3 - Oxide O 2- Calcium Ca 2+

Write down the formulae for these ionic compounds a)Potassium Chloride b)Magnesium Carbonate c)Magnesium Chloride d)Sodium Carbonate e)Magnesium Hydroxide f)Magnesium Nitrate

1.Write down the electron configuration of a chlorine atom 2.Write down the electron configuration of a chloride ion 3.Write down the symbol and charge of the chloride ion 4.Describe HOW ions are formed 5.Describe WHY ions are formed 6.Describe the difference between atoms and ions

Question ONE a)atoms of same number of protons but different number of neutrons b)number of protons c)number of protons + neutrons d)protons, electrons, neutrons Question TWO a)Sodium = 2, 8, 1 b)Oxygen = 2, 6 c)Calcium = 2, 8, 8, 2 d)Si (silicon) = 2, 8, 4 e)Ar (argon) = 2, 8, 8

Question FOUR Ions have charge, but atoms don’t. Atoms are neutral (#protons = #electrons), but ions have charge because they have unequal number of protons and electrons after losing/gaining electrons. Question FIVE Ions are formed when atoms lose or gain electrons, in order to obtain full outer shell.

Ions An ion is an atom or a group of atoms that has gained or lost one or more electrons. Atoms always want to have outer shells that are complete (full), giving it stable electron structure. Atoms which gain electrons become ________ charged – called “anions” Atoms which lose electrons become ________ charged – called “cations”

Ion formation - Example 1.What is the electron configuration (arrangement) of a sulfur atom? 2.Will it lose or gain electron(s)? 3.How many? 4.Protons (+) vs. Electrons (-) 5.Cation or anion? 6.What is the new electron configuration?

LiF Neutral Atoms Atomic # : # or electrons in a neutral atom :

LiF Ions Cation Li + Anion F -

Be O Ions Cation Be 2+ Anion O 2-

Cations (positively charged ions) Hydrogen H + Lithium Li + Sodium Na + Calcium Ca 2+ Magnesium Mg 2+ Zinc Zn 2+ Aluminium Al 3+

Anions (negatively charged ions) Chloride Cl - Oxide O 2- Sulfide S 2- Hydroxide OH - Nitrate NO 3 - Sulfate SO 4 2- Carbonate CO 3 2-

Hydrogen H + Lithium Li + Sodium Na + Calcium Ca 2+ Magnesium Mg 2+ Zinc Zn 2+ Aluminium Al 3+ Iron II Fe 2+ Iron III Fe 3+ Chloride Cl - Oxide O 2- Sulfide S 2- Hydroxide OH - Nitrate NO 3 - Sulfate SO 4 2- Carbonate CO 3 2-

Practical – producing “iron sulfide”

1.Give names of any three cations 2.Give names of any three anions 3.What is the difference between an atom and an ion?

Writing formulae for ionic compounds

1.Look at the charges of the ions you are putting together. 2.If “positive charge = negative charge”, then just put their formulae together (easy!) Example: Mg 2+ + CO 3 2- → MgCO 3 3.Remember – there is no need to write down the charges (the little numbers on the top with plus and minus) on the final answer How to write down the formulae for ionic compounds

4.But what about putting these two together? Na + and CO 3 2- The charges are unbalanced here. To make it balanced, you need TWO sodium ions (Na + ). 2Na + + CO 3 2- → Na 2 CO 3 5.What about these two? Ca 2+ and Cl - Ca Cl - → CaCl 2

6.Be careful when you deal with polyatomic ions (e.g. NO 3 - ). You have to put brackets around them if you have more than one. For example: Ca OH - → Ca(OH) 2 Ca NO 3 - → Ca(NO 3 ) 2 7.Can you work out this one? Al 3+ + CO 3 2- → __________

Try these… 1.Sodium chloride 2.Sodium hydroxide 3.Sodium nitrate 4.Magnesium Oxide 5.Magnesium sulfate 6.Magnesium carbonate 7.Calcium carbonate

Now try these… 1.Sodium carbonate 2.Lithium carbonate 3.Potassium sulfate 4.Sodium phosphate 5.Magnesium chloride 6.Calcium chloride 7.Aluminium chloride

Are you ready for these? 1.Calcium hydroxide 2.Magnesium hydroxide 3.Magnesium nitrate 4.Zinc nitrate 5.Aluminium hydroxide 6.Aluminium nitrate 7.Aluminium carbonate

Chemical Formulae  A molecule of glucose contains what elements? In what proportions? C 6 H 12 O 6 Carbon, Hydrogen and Oxygen Twice as many Hydrogen as Carbons and Oxygens.  Sucrose is two glucose molecules bonded together. What is its chemical formula?

Ionic Compounds sodium chlorine Use Lewis dot diagrams Na Cl 1+ 1-

Ionic Compounds sodium chlorine sodium chloride NaCl Cl Na

Ionic Compounds  How do we write the Formula? Reactant + ReactantProduct Na + + Cl - NaCl

Ionic Compounds lithium oxygen Li O

Ionic Compounds lithium oxygen Lithium oxide Li 2 O O Li Li

Ionic Compounds  How do we write the Formula? Reactant + ReactantProduct Li + + O 2- Li 2 O 2

O O Try This ! aluminumoxygen aluminum oxide Al 2 O 3 Al O

Ionic Compounds  How do we write the Formula? Reactant + ReactantProduct Al 3+ + O 2- Al 2 O 3 23