1. Electrons, Bonding Naming Compounds

2. ELECTRONS

3. Electron Arrangement Electrons travel in orbits around the nucleus (similar to planets around the sun) –1 st orbit holds 2 electrons –2 nd orbit holds 8 electrons –3 rd orbit holds 18 electrons –In general the n th orbit can accommodate 2n 2 Atoms are ‘stable’ when they have full electron orbitals, therefore atoms gain or lose electrons, resulting in ions (charged particles)

4. EXAMPLE Lithium has 3 electrons, 2 of which are on the first level and the 3 rd on the second level. We write this as (2,1) 3+

5. Some WEIRD STUFF Say you have 21 electrons. You’d think you’d be able to write it like (2, 8, 11). However, when filling the 3 rd energy level once it hits 8 you put the other electrons in the 4 th energy level till you have two. You can then start filling the 3 rd energy level. So 21 electrons would be (2,8,9,2)

6. POSITIVE OR NEGATIVE Atoms are ‘stable’ when they have full electron energy levels, therefore atoms gain or lose electrons, resulting in ions (charged particles) Group 1 metals (Li, Na….) all tend to lose 1 electron (Li +, Na + ) Group 2 metals (Be, Mg…) all tend to lose 2 electrons (Be 2+, Mg 2+ ) Group 7 elements (F, Cl…) all tend to gain 1 electron (F -, Cl - ) Group 6 elements (O, S….) all tend to gain 2 electrons (O 2-, S 2- ) The Transitional metals all lose electrons to form positive ions. CATION – are the ions with a positive charge ANION – are the ions with a negative charge

7. Predict the charge of; –NaMg –CaAl –BrS –NO Na = 1+ Mg = 2+ Ca = 2+Al = 3+ Br = 1-S = 2- N = 3-O = 2-

8. Bonding

9. The Octet Rule As mentioned before: –Atoms are ‘stable’ when they have full electron orbitals, therefore atoms gain or lose electrons, resulting in ions (charged particles) Therefore most Group A elements want to have either 2, 10, 18, 36, 54, or 86 electrons 1A2A3A6A7A8A H + Li + K + Rb + Cs + Be 2+ Mg 2+ Ca 2+ Sr 2+ Al 3+ O 2- S 2- Se 2- Te 2- F - Cl - Br - I - At - He Ne Ar Kr Xe

10. There are 2 major types of bonding 1.Ionic bonding – When a metal gives one (or more) electron/s to a non-metal. 2.Covalent bonding – When two non- metals ‘share’ an electron.

11. Example of Ionic Bonding

12. Formulae for Ionic Compounds Aluminium oxide contains Al 3+ and O 2-. FORMULA: xA = yB –Where A is the charge on the cation and B is the charge on the Anion. So X(3) = Y(2) ----- use the smallest numbers X=2 and Y=3 So you’ll have 2 Al and 3 O == Al 3 O 2

13. COVALENT BONDS Easiest way to figure out covalent bonds is through DOT Diagrams. The number of dots around the element is determined by what GROUP it’s in: The elements in the groups 3 and up want to have 8 electrons (dots) around them 12345678 LiBeBCNOFNe

14. Single Covalent bond ClCl I wish I had one more electron so I’d have 8 HEY LETS SHARE AN ELECTRON EACH SO IT LOOKS LIKE WE”VE GOT 8 EACH !!!

15. DOUBLE Covalent bond O O HEY LETS SHARE 2 ELECTRONs EACH SO IT LOOKS LIKE WE”VE GOT 8 EACH !!!

16. Examples of Covalent Bonding H

17. 1.Explain the difference between ionic and covalent bonding with the use of diagrams 2.Determine whether each of the following compounds would contain ionic or covalent bonding a.Lithium and chlorine b.Boron and bromine c.Aluminium and iodine d.Sulphur and oxygen 1..Ionic bonding involves ‘donating and receiving’ electrons, whereas covalent bonding involves ‘sharing’ of electrons 2.. a. Ionic b. Covalent c. Ionic d. Covalent