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CHEMICAL BONDING PART 1 IONIC BONDING

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1 CHEMICAL BONDING PART 1 IONIC BONDING

2 Elements Elements are the simplest substances. There are about 100 different elements N S O C Fe K Each elements has just one particular type of atom that is different to the atoms in any other element N Even in elements atoms usually join (bond) together. In some elements atoms bond to form small simple structures. In other elements atoms bond into giant structures with millions of atoms.

3 Water – a simple structure DNA – a large & complex structure
Compounds Compounds are formed when different elements chemically react together. In these reactions different types of atom become chemically bonded. Like elements some compounds have small simple structures with just a few atoms bonded together Other compounds have large, complex structures containing thousands or even millions of bonded atoms. O H Water – a simple structure DNA – a large & complex structure

4 Compounds are not just mixtures
Reacting is different to just mixing. The physical and chemical properties of compounds are very different to their original elements. COMPOUND ELEMENTS Carbon oxygen Carbon dioxide C O C O (black solid) (colourless gas, that supports combustion) (a colourless gas, that extinguishes fire)

5 Rust consists of iron combined with oxygen
Activity Copy the Table and fill in the last column. Name Formula Element or compound Rust consists of iron combined with oxygen Sodium chloride NaCl compound Nickel Ni element Copper sulphate CuSO4 compound Water H2O compound Oxygen O2 element Rust Fe2O3 compound Mercury Hg element Sand SiO2 compound

6 exist in layers (or shells) around the outside of the nucleus
Bonding and atoms To understand bonding we must know a little about the atoms from which elements are made. Atoms consist of three types of particles that are even smaller than atoms: Protons } These exist in Neutrons } the nucleus. Electrons } exist in layers (or shells) around the outside of the nucleus

7 No charge on element atoms
Two of the three particles in atoms have an electrical charge. Protons Neutrons Electrons -1 BUT atoms have equal numbers of protons and electrons. This means their overall charge = zero. For example Fluorine 9 protons 9+ 9 electrons 9- 10 neutrons 0 Total Charge 0 19 F 9 20 Ne 10 Neon Copy & Fill in the gaps ___ protons ___ ___ electrons ___ ___neutrons ___ Total Charge ___ 10 10+ 10 10- 10

8 Noble Gases: full shells
The electrons around the outside of atoms are arranged in layers called shells 1st Shell: electrons 2nd Shell: electrons 3rd Shell: electrons Each shell has a maximum number of electrons that it can hold. In noble gases the shells are completely full rather than partially full. During bonding other atoms try to attain the “full electron shell” structure of the noble gases.

9 Atoms can be joined together in 3 possible ways
Types of bonding Atoms can be joined together in 3 possible ways Metal and non-metal Non-metals only Metals only Ionic Bonding Covalent Bonding Metallic Bonding All three types involve changes in the electrons in the outermost electron shells of the atoms

10 IONIC BONDING

11 IONIC BONDING Most ionic compounds contain a metal and a non-metal.
When metals react they lose outer shell electrons to leave a full electron shell. This produces a charged atom (ion) with a + charge. Lose 1 or more electrons Neutral atom n+ Positive ion When non-metals react with a metal they gain electrons to achieve a full electron shell. Gain 1 or more electrons Neutral atom n- Negative ion

12 Opposites attract – lattices
The oppositely charged ions are attracted into a lattice that gets bigger and bigger until it consists of millions of ions + - + - + - + - + - opposites attract And ion, and ion, and ion!

13 Lattices are 3-Dimensional
We have shown ions attracting and building into a 2 dimensional sheet. + - In fact the whole process will be going on in three dimensions to build up a giant 3-D lattice. + - And so on to build a giant 3-D lattice with millions of ions. + -

14 Ions and electron structures
Metals lose electrons to form positive(+) ions called cations. n+ Non-metals gain electrons to form negative (–) ions called anions. n- We know that the atoms lose or gain electrons to achieve full electron shells. To understand more about how ionic compounds form we must look at what is happening to the outer shell electrons.

15 Formation of sodium chloride 1. Formation of sodium ions
Sodium has 1 electron in its outer shell. If it loses this it will have no partially filled shells. Na Na+ Loses 1 electron Sodium atom (2.8.1) Sodium 1+ ion (2.8.0) This only happens if there is another atom able to accommodate the lost electron.

16 Formation of sodium chloride 2.Formation of Chloride ions
Chlorine has 7 electrons in its outer shell. If it gains 1 electron it can achieve a full outer electron shell. It is, therefore, going to be able to accept the electron that the sodium wants to lose. Cl Cl Gains 1 electron (from sodium) Chlorine atom (2.8.7) Chlorine I - ion (2.8.8)

17 Formation of Sodium Chloride- the overall process.
Sodium loses its outer electron. Chlorine gains it. The result is both end up with full shells Cl Na Two oppositely charged ions are formed, which attract. Millions of such pairs form a giant lattice Na Cl

18 Simpler electron diagrams
We can assume full inner electron shells. We can therefore sometimes shorten bonding diagrams by omitting to draw the inner electron shells. Na Cl Na Cl

19 Bonding in Magnesium Oxide
More than one electron may be transferred between atoms in ionic bonding. O Mg 2.8.2. 2.6 Magnesium atom Oxygen atom Mg2+ O2- 2.8 Magnesium Oxide

20 Draw a simplified bonding diagram (omitting inner shells) for magnesium oxide.
Mg O Magnesium atom Oxygen atom Mg2+ O2- Magnesium Oxide

21 Copy the diagram and draw another box showing the electron configuration in sodium fluoride.
Na 2.8.1. 2.7 Sodium Fluoride Na+ F- Sodium atom Fluorineatom 2.8 2.8

22 Bonding in Lithium Oxide
The bonding in lithium oxide is more complicated in that there are different numbers of each atom. Li O Li+ O2-

23 Bonding in Lithium Nitride
The bonding in lithium nitride similarly involves different numbers of each atom. Li Li+ N3- Li N

24 Bonding in Aluminium Fluoride
In aluminium fluoride it is the non-metal atoms that we need more of. Al F F Al

25 Activity Following the previously shown slides draw bonding diagrams for the compounds formed from the following atoms: Lithium (2.1) and fluorine (2.7) Sodium (2.8.1) and sulphur (2.8.6) Magnesium (2.8.2) and sulphur (2.8.6) Magnesium (2.8.2) and fluorine (2.7) Aluminium (2.8.3) and nitrogen (2.5) Remember that the total number of electrons lost by the metal must equal the total number of electrons gained by the non-metal

26 Electrons Lost = Electrons Gained
Both sodium chloride and magnesium oxide are simple ionic compounds. In both cases the metal and non-metal need to lose or gain the same number of electrons respectively. Na Cl 1 electron Na+ Cl- 2 electrons O Mg O2- Mg2+ This is not always the case.

27 Different numbers of electrons
Consider the reaction of sodium with oxygen. Sodium (2.8.1) needs to lose 1 electron. Oxygen (2.6) needs to gain 2 electrons This can only happen if there are two sodium ions formed for every one oxygen ion formed. Na O Na+ O2- 1 electron per sodium The formula will be Na2O.

28 Different numbers of electrons
Consider the reaction of magnesium with chlorine. Magnesium (2.8.2) needs to lose 2 electron. Chlorine (2.8.7) needs to gain 1 electrons We need 2 chlorines for every one magnesium. Cl Mg Mg2+ Cl- 2 electrons The formula will be MgCl2

29 Charges on ions When atoms form ions they aim to attain electron shells that are either completely full or completely empty. If we know the electron configuration of an atom we can usually work out how many electrons it must lose or gain to achieve a noble gas configuration. This will tell us the charge on its ion.

30 Charges and Metal ions 2.8.2  Mg2+ 2.8.3  Al3+ 2.1Li+
Metals usually lose electrons to empty this outer shell. The number of electrons in the outer shell is usually equal to the group number in the Periodic Table. For example, Mg 2.8.2  Mg2+ Al 2.8.3  Al3+ Li 2.1Li+

31 Charges and non-metal ions
Outer shells with 5 or more electrons usually gain electrons to fill up the outer shell. For example, Oxygen (2.6) gains 2 electrons to form O2- Chlorine (2.8.7) gains 1 electron to form Cl- Cl O 2.62.8 O  O2- 2.8.7 Cl  Cl-

32 Activity Copy out and fill in the Table below showing what charge ions will be formed from the elements listed. H He Li Na K Be Sc Ti Mg V Cr Mn Fe Co Ni Cu Zn Ga Ge Se Br Ca Kr Al P N O S Cl F Ne Ar Si B C As Na Charge Outer electrons Ne Br O Al K Ca Cl N Li Symbol 1 5 7 2 3 6 8 1+ 3- 1- 2+ 3+ 2-

33 The formulae of ionic compounds
This is most quickly done in 5 stages. Remember the total + and – charges must =zero For example, the formula of calcium bromide. Symbols: Ca Br Charge on ions Need more of Br Ratio of ions 1 2 Formula CaBr2 Ca2+ Br- Br Ca 2 electrons

34 The formulae of ionic compounds
For example, the formula of aluminium bromide. Symbols: Al Br Charge on ions Need more of Br Ratio of ions 1 3 Formula AlBr3 Al3+ Br- Br Al 3 electrons

35 The formulae of ionic compounds
For example, the formula of aluminium oxide. Symbols: Al O Charge on ions Need more of O Ratio of ions 2 3 (to give 6 e-) Formula Al2O3 Al3+ O2- O Al 2e-

36 Activity Metals: Li Ca Na Mg Al K Non-Metals: F O N Br S Cl
Using the method shown on the last few slides, work out the formula of all the ionic compounds that you can make from combinations of the metals and non-metals shown below: Metals: Li Ca Na Mg Al K Non-Metals: F O N Br S Cl

37 More Complicated Formulae
Ionic compounds may contain ions consisting of groups of atoms rather than a single atom. Here are some more complicated ions you may come across. Atoms present Charge Formula Ion 2- 1- 1+ CO32- OH- NH4+ SO42- NO3- carbonate hydroxide ammonium sulphate nitrate N O S H C

38 More Complicated Formulae
When working out formula you simply treat the entire group of atoms as though it were a single atom. The only difficulty is to do with how we write down the final answer. For example, what is the formula of lithium nitrate? Symbols: Li NO3- Charge on ions Need more of neither Ratio of ions 1 1 Formula LiNO3

39 More Complicated Formulae
What is the formula of magnesium nitrate? Symbols: Mg NO3- Charge on ions Need more of NO3- Ratio of ions 1 2 Formula Mg(NO3)2 The brackets around the NO3- ion show that the 2 refers to two complete NO3- ions. It represents a total of 2 nitrogens and 6 oxygens with each magnesium ion.

40 More Complicated Formulae
What is the formula of sodium sulphate? Symbols: Na+ SO42- Charge on ions Need more of Na+ Ratio of ions 2 1 Formula Na2SO4 No brackets here as only one SO42- ion needed. Note although Na contains 2 letters it only represents a single atom – so no brackets!

41 Write down how to work out the formula of aluminium hydroxide.
Symbols: Charge on ions Need more of Ratio of ions Formula Al3+ OH- 3+ 1- OH- 1 3 Al(OH)3 Again we need brackets as 3 complete OH- ions are needed meaning that for each aluminium there are 3 oxygens and 3 hydrogens.

42 Write down how to work out the formula of ammonium sulphate.
Symbols: Charge on ions Need more of Ratio of ions Formula NH4+ SO42- 1+ 2- NH4+ 2 1 (NH4)2SO4 Again we need brackets as 2 complete NH4+ ions are needed meaning that for each sulphate ion there are 2 nitrogen and 8 hydrogens.

43 Need to get total charge =6
Write down how to work out the formula of aluminium sulphate. Symbols: Charge on ions Need more of Ratio of ions Formula Al3+ SO42- 3+ 2- Need to get total charge =6 2 3 Al2(SO4)3 No brackets for Al as only one atom even though it’s 2 letters. We do need brackets around the SO4 to show it is 3 complete sulphate ions.

44 Copy this choosing words from below to fill the gaps.
lose lattices electrons gain metal Formed when a _____ and non-metal react. Metals ___ electrons to empty their outer electron shell. Non-metals _____ electrons to fill their outer electron shell. The ratio of metal ions to non-metal ions will depend upon the number of ________ lost and gained. The ions formed join up into giant _____. metal lose gain electrons lattices.

45 Which of the following will have ionic bonding?
Copper chloride Iron Brass Sulphur dioxide

46 Which of the following is NOT true of ionic bonding?
Metal ions have a + charge Non-metal ions have a - charge They form a 2 dimensional lattice They have giant structures

47 Which of the following is true about the oxide ion?
Formed by oxygen atoms losing 2 electrons. Oxygen ions have an empty second shell Exist in pairs Have a 2- charge 16 O 8

48 Which of the following is true about the sodium ion?
Has a 2,8,1 electron arrangement Formed by sodium atoms gaining 1 electron. Sodium ions have an empty second shell Have a 1+ charge 23 Na 11

49 What formula compound will be formed from Mn4+ and O2- ions?
Mn2O4 MnO2 Mn2O MnO4

50 What formula compound will be formed from Ga3+ and SO42- ions?
Ga2(SO4)3 Ga3(SO4)2 Ga2S3O12 Ga (SO4)3


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