Types of Compounds

1. Types of Compounds • There are two types of compounds • Ionic Compounds • These are compounds where electrons are transferred from one atom to another to give each atom full outer shells. • This forms a (+) ion and a (-) ion. These oppositely charged ions are attracted to each other to form an ionic bond • Eg Na = 2,8,1 Now Na+ is formed • Cl = 2,8,7 Now Cl- is formed • The Na+ and Cl- come together to form NaCl (now we don’t write the charges) The Na electron is transferred to the Cl atom

2. Ionic compounds are always between a metal and a non metal eg Na (metal) Cl (non metal) make NaCl In year 11 you will be given a table of ions – you don’t have to remember them. But you must know how to write balanced formula for ionic compounds using these ions

4. Task : write the chemical formula for sodium oxide in your book Step one: Write out the two ions from the chart with their charges ie Na+ and O2- Step two : Make the two charges balance (in other words are there the same number of (+) as (-) ) Na = +1 and O = -2 no they don’t balance. Now the seesaw doesn’t balance Step three: You must add an extra Na+ ion to make the (+) and (-) balance which ion do you think you will need to add to the seesaw?

5. Yes you are correct you need to add one Na+ to the left hand side of the seesaw Now you write the formula for sodium oxide as Na2O This tells us in each particle of sodium oxide (Na2O) There are two Na+ ions and one O2- ion

6. Task : Find the formula for aluminium oxide Step one Write out the ions from your table ie Al 3+ and O 2- Step two : Make the two charges balance (in other words are there the same number of (+) as (-) ) Al = +3 and O = -2 no they don’t balance. Step three: Add ions to both sides until the charges balance Al 3+ O 2- Al 3+ O 2- O 2- Al2O3 Aluminium oxide

7. You try this one write out each step : Find the formula for magnesium nitrate Step one Write out the ions from your table ie Mg2+ and NO3- Step two : Make the two charges balance (in other words are there the same number of (+) as (-) ) Mg = +2 and NO3- = -1no they don’t balance. Step three: Add ions to both sides until the charges balance NO3- Mg 2+ Then write formula NO3- Mg(NO3)2

8. Starter Task : Write the chemical formula for Calcium hydroxide in your book Step one: Write out the two ions from the chart with their charges Step two : Make the two charges balance by adding ions Step three: Write the finished formula without the charges

9. You can quietly read the following 6 slides or you can copy them down

10. Types of Compounds 2. Covalently bonded Compounds Covalent bonds involve atoms sharing electrons to form molecules. Molecules can be compounds made of two or more different atoms eg CO2, H2O, C6H12O6 etc Molecules can also be elements where 2 identical atoms are covalently bonded together eg H2, N2, O2, Cl2 etc

11. Remember covalent bonds involve the sharing of electrons This is how both carbon and hydrogen achieve full valence (or outer) shells in CH4. When atoms form covalent bonds they form molecules.

12. How to draw the bonding structure of a covalent molecule First draw both atoms with their valence electrons

13. Task: Making Molecules 1. In pairs use the model atoms to make a methane (CH4) molecule C atoms are black H atoms are white Use the long grey bonds to join them 2. Then make an H2O molecule H = white O = red 3. Then make a SO2 molecule S = yellow O = red 4. Then make an H2 molecule Show me when you have finished each one

14. Task: Making Molecules Then make a carbon dioxide (CO2) molecule Then make a glucose (C6H12O6) molecule (hint make a ring of 6 carbons) Show me when you have finished each one

15. Covalent bonding in methane (CH4) From the carbon atomic number we find: 6 carbon has an electron arrangement of 2, 4 This means carbon has 4 electrons in its valence (or outer) shell C 12 We can draw the 4 valence electrons of carbon like this: How many electrons does carbon need in its valence (or outer) shell? Ans: 8 electrons

16. From the hydrogen atomic number we find: 1 hydrogen has an electron arrangement of 1 This means hydrogen has 1 electron in its valence (or outer) shell H 1 We can draw the valence electron of hydrogen like this: How many electrons does hydrogen need in its valence (or outer) shell? Ans: 2 electrons

17. Place 4 hydrogen atoms around the C atom so that each H shares an electron with a C electron This sharing of electrons between H and C also means the C atom has a full valence shell of 8 electrons Each H atom shares one electron with one C electron to give each H a full valence shell of 2 electrons Can you see that both H and C atoms have full valence shells by sharing their electrons?

18. Ions and Molecules Ions Write down the following filling in the gaps. Ions are atoms that have g_____ or l_____ electrons to form p_______ or n________ ions 3 examples of ions are _________ion symbol ( ) , ________ ion symbol ( ) and _________ ion symbol ( ). Choose from : smallest, neutrons, covalent, electrons, gained, loss, negative, positive, valence, outer, protons, water, hydrogen gas, H2, CO2, H2O

19. Atoms, Ions and Molecules Atoms Write down the following filling in the gaps. Atoms are the s________ particles that make up all things. They consist of ________ and _________ in the nucleus with e________ in shells around the nucleus. 3 examples of atoms are _________ symbol ( ) , ________ symbol ( ) and _________ symbol ( ). Choose from : smallest, neutrons, covalent, electrons, gained, loss, negative, positive, valence, outer, protons, water, hydrogen gas, H2, CO2, H2O

20. Atoms, Ions and Molecules Molecules Write down the following filling in the gaps. Molecules are where two or more atoms share electrons in a c________ bond to give both atoms full v______ or o______ shells. 3 examples of molecules are w_______ formula ( ) , c________ d_______ formula ( ) and h______ g___ formula ( ). Choose from : smallest, neutrons, covalent, electrons, gained, loss, negative, positive, valence, outer, protons, water, hydrogen gas, H2, CO2, H2O

21. What is an ion? • An anion is an atom that has gained electron(s) to form a (-) ion e.g Cl- (Chloride) S2- (Sulfide) or a cation is an atom that has lost electron(s) to form a (+) ion e.g Na+ (Sodium) Fe2+ (iron (ll) ion) (aka Ferric ion) Fe3+ (iron(lll) ion ) (Ferrous)

22. Compounds can be two types – Copy this neatly into your book 1. Compounds can be Ionic Ionic compounds form when atoms lose and gain electrons to form charged (+) and (-) . These oppositely charged ions are attracted together to form an ionic bond. Ionic bonds always occur between a metal and non metal. Eg Na (+) and Cl (-) come together to form NaCl

23. Compounds can be two types – Copy this neatly into your book 2. Compounds can be Covalent These atoms share electrons so that each atom has a full outer shell. This sharing of electrons is called a covalent bond. Covalently bonded atoms form molecules. Molecules are always between non metal atoms. Examples of molecules are CH4 methane, H2O water, CO2 carbon dioxide

24. Atoms and elements A substance made of one type of atom is called an element e.g. a piece of Aluminium (symbol Al) consists of only aluminium atoms bonded together and is called an element.

25. Molecules • Some elements are unstable as single atoms and only exist as 2 atoms covalentlybonded together to form a molecule. These are usually gases e.g H2 , N2, Cl2, O2

26. Compounds and Molecules Some compounds are molecules that contain 2 or more different atoms covalently bonded together. Some common molecular compounds are: • CO2 (carbon dioxide) • H2O (water) • CH4 (methane) • C6H12 O6 (glucose)

27. Mg + O2 Zn + HCl Fe + Cl2 NaOH + HCl CH4 + O2 Ca + H2O NaOH + H2SO4 CH3OH + O2 MgO ZnCl2 + H2 FeCl3 NaCl + H2O CO2 + H2O Ca(OH)2 + H2 Na2SO4 + H2O CO2 + H2O Balancing Reactions 2 2 2 2 2 4 2 2 2 3 2 2 2 2 3

28. Simple formulae to learn H2O CO2 NH3 H2 O2 N2 SO2 Water Carbon dioxide Ammonia Hydrogen Oxygen Nitrogen Sulphur dioxide NaCl CaCl2 MgO HCl H2SO4 HNO3 NaOH Ca(OH)2 CaCO3 Al2O3 Fe2O3 Sodium chloride Calcium chloride Magnesium oxide Hydrochloric acid Sulphuric acid Nitric acid Sodium hydroxide Calcium hydroxide Calcium carbonate Aluminium oxide Iron oxide

29. Acids Acids release hydrogen ions (H+) in water to give acidic solutions Common Lab Acids are: Sulfuric acid (formula H2SO4 ) Nitric acid (formula HNO3) Hydrochloric acid (formula HCl) These are strong acids because they form a lot of H+ ions in water EgHCl (l) H+ (aq) + Cl- (aq) Eg H2SO4 (l) 2H+ (aq) + SO42- (aq)

30. Acids Other Acids found around the home are: ethanoic acid (formula CH3COOH ) this is the acid found in vinegar. Tartaric acid (formula C4H6O6)used in cooking Citric acid ( formula C6H8O7) this is the acid found in oranges and other fruits. ascorbic acid is another acid known as vitamin C. These acids are called weak acids because they form a small number of H+ ions in water

31. Bases • Bases are substances that release hydroxide ions (OH-) in water. • Eg NaOH (s) Na+ (aq) + OH- (aq) • Eg KOH (s) K+ (aq) + OH- (aq) Strong bases give off lots of OH- ions and weak base give off less OH- ions Common strong bases are: • Sodium hydroxide (NaOH) • Potassium hydroxide (KOH) • Ammonium hydroxide (NH4OH) Many cleaning agents are bases eg oven cleaners, window cleaners

32. The pH Scale The amount of H+ ions given off by an acid are measured by the pH scale 1 on the pH scale means there are a lot of H+ ions in the water and the solution is said to be acidic 14 on the pH scale means there are very few H+ ions in the water but a lot of OH- ions creating a basic solution

33. Draw the pH scale below your book Neutral Eg water acid base The colours below are the colours for the different pH numbers with universal indicator this indicates how acidic or basic a solution is Task – gently shade your pH scale these colours

34. acid neutral basic Anything less than 7 on the pH scale is called an acid neutral Strong acid Weakacid

35. acid neutral basic Indicators can also tell us how many OH- ions a base will give off and this gives us an indication of how basic a solution is. neutral Strong base Weak base

36. Litmus paper is another indicator Beaker 1 Blue litmus Beaker 2 Red litmus Which beaker contains the acid and which one contains the base? Remember blue litmus paper tests for acids Red litmus tests for bases Acid Base (H+) (OH-) Which beaker has more OH- ions? Which beaker has more H+ ions?

37. Litmus paper can also tell us Whether we Have an Acid or a base. Litmus paper can be red or blue Acids turn blue litmus paper red Bases turn red litmus paper blue

38. Neutralisation hydroxide (OH-) ions are the opposite to H+ When there are equal amounts of H+ and OH- ions in a solution they will react to form pure water (H2O) in a neutralisation reaction – the neutralisation reaction is below H+ + OH- H2O (water is neutral and has a pH of 7) From acid From base So bases eg NaOH, KOH can neutralise acids! and acids eg HCl,H2SO4 can neutralise bases!

39. Gas tests All carbonates eg _______ react with any acid to from CO2 (carbon dioxide) gas. CaCO3 Give a balanced equation for an acid/carbonate reaction CaCO3 + 2HCl CaCl2 + CO2 + H2O How do you test for CO2? The limewater test bubbled CO2 through limewater CO2 + Ca(OH)2 CaCO3 + 2H2O

40. How do you test for O2? (Oxygen) The glowing splint test KMnO4 MnO2 + O2

41. Finally how do you test for H2 (hydrogen)? The pop test Give a balanced reaction for the magnesium and hydrochloric acid reaction Mg + 2HCl MgCl2 + H2 Give a balanced reaction for the combustion of the hydrogen

42. Physical Properties of metals

43. Metal Structure • A metal consists of a regular arrangement of positive ions held together by a 'sea' of electrons.

44. Metal structure Starter Metals consist of p______ metal ions surrounded by n______ electrons. The attraction of the e_______ for the p_____ ions acts like a glue that holds metals atoms together

45. Activity On the periodic table in your book colour the metals red and nonmetals blue leave the metalliods (these are elements found on the border line between the metals and non metals) white. Give names to the following metal symbols: Al - Zn - Ag - Ni - Ca - Cu – Fe - Li - Mg – Pb - Na - Au - Aluminium Zinc Silver Copper Nickel Calcium Iron Lithium Magnesium Lead Sodium Gold

46. Metal Structure • A metal consists of positive ions held together by a 'sea' of electrons. • The electrons account for the lustrous appearance of metals • Because the electrons can move freely they conduct electricity, however the positive ions can only vibrate in the one spot. This means metals also conduct heat as well Note This type of metal bonding between positive ions and electrons in metals is strong giving metals high melting points.

47. Why metals conduct heat The word particle in this passage refers to the metal ions. Demo by heating spatula with paper clips attached by vasoline

48. Why most metals can be bent or shaped As the metallic bonds do not act in a particular direction, the rows of positive ions can slide over one another easily. This allows the metal to be bent or shaped. This structure allows metals to be bent (malleable) or made into wires (ductile)

49. Metal structure Starter Metals consist of p______ metal ions surrounded by n______ electrons. The attraction of the e_______ for the p_____ ions acts like a glue that holds metals atoms together

50. Isotopes • An isotope is an atom with a different number of neutrons • The above are all naturally occurring isotopes of hydrogen