1. How ions are formed.

2. I think that I’ve lost an electron. What do you mean ?

4. It just feels like something is missing! Are you sure ?

6. I’m positive !

7. Neutral atoms have the same number of positive protons as they have negative electrons. If an atom gains or loses electrons there is an imbalance of charge, ad it is called an ION.

10. If only I could get rid of this spare electron in my outer shell. Then I’d be as cool as neon. I just need one more electron to complete my outer shell. Then I’d be just like that dude argon. What type of ions will be formed if Na gives its electron to Cl?

11. You will form a Na +1 ion when the sodium atom loses its electron, and a Cl -1 ion when the chlorine atom gains its extra electron.

12. Who will take my two spare electrons? We will!! What type of ions will be formed if Mg gives its electrons to the Cl’s?

13. You will form a Mg +2 ion when the magnesium atom loses its electrons, and two Cl -1 ions when the chlorine atoms each gains one electron.

14. He He. While calcium isn’t looking I can steal his two outer electrons. He He. What type of ions will be formed if O takes two electrons from Ca?

15. You will form a Ca +2 ion when the calcium atom loses its two electrons, and an O -2 ion when the oxygen atom gains two extra electron.

16. What type of ions will be formed if All 6 electrons from Al are evenly Shared amongst the three O’s?

17. You will form two Al +3 ion when the aluminium atoms lose their electrons, and three O -2 ion when each oxygen atom gains two extra electrons.

18. In the examples that we’ve looked at so far, Do metals form positive or negative ions? ___________________________ Do non-metals form positive or negative ions? ___________________________

19. In the examples that we’ve looked at so far, Do metals form positive or negative ions? ____positive_______________ Do non-metals form positive or negative ions? ___________________________

20. In the examples that we’ve looked at so far, Do metals form positive or negative ions? ____positive_______________ Do non-metals form positive or negative ions? ____negative_______________

22. Group 1A elements ie H, Li, Na, K, etc will form +1 ions. Group 2A elements ie Be, Mg, Ca, Ba etc will form +2 ions. Group 3A elements ie B, Al, Ga etc will form +3 ions. Group 5A elements ie N, P, As etc will form –3 ions. Group 6A elements ie O, S, Se etc will form –2 ions. Group 7A elements ie F, Cl, Br, I etc will form –1 ions. Group 8A elements never form ions. With reference to the number of electrons that the noble gases have, can you explain why each of the above groups gain or lose a particular amount of electrons?

23. The other elements (the Transition metals, the Lanthanides metals and Actinide metals) can form more than one type of positive ion each. eg Sometimes chromium will lose two electrons and form a +2 ion. And sometimes chromium will lose three electrons and form a +3 ion. This could be confusing so chemists have decided to give a different name to each ion. If chromium loses two electrons the resulting ion (Cr+2) is called chromium II. And if chromium loses three electrons, then the resulting ion (Cr+3) is called chromium III.

24. For example: The charge on a copper I ion is +1. The charge on a copper II ion is +2. What is the charge on each of the following ions? mercury II__________ iron III__________ iron II__________ mercury I__________

25. For example: The charge on a copper I ion is +1. The charge on a copper II ion is +2. What is the charge on each of the following ions? mercury II_____+2___ iron III_____+3___ iron II_____+2___ mercury I_____+1___

26. Name each of the following ions: (a) Cu +2 ______________________ (b) Fe +3 ______________________ (c) Cr +2 ______________________ (d) Hg +2 ______________________

27. Name each of the following ions: (a) Cu +2 __copper II ___________ (b) Fe +3 __iron III ___________ (c) Cr +2 __chromium II _________ (d) Hg +2 __mercury II _________

28. Another naming convention that chemists use is for non-metal ions. If a non-metal element forms an ion by gaining electrons we add –ide to the end of the non-metal’s name. For example if a chorine atom gains one electron to form a –1 ion, Cl-1. This ion is called the chloride ion.

29. Name each of the following ions: (a) O -2 ______________________ (b) S -2 ______________________ (c) Br -1 ______________________ (d) N -3 ______________________

30. Name each of the following ions: (a) O -2 ___oxide ion _________ (b) S -2 ___sulfide ion _________ (c) Br -1 ___bromide ion _________ (d) N -3 ___nitride ion _________

31. You are so radical man!!

32. Sometimes when groups of atoms join together, then the whole group will gain or lose electrons. In the previous slide the potassium atom loses one electron to become a K+ ion. The group of atoms (one manganese atom and four oxygen atoms) combine together and share this electron. This forms an ion known as a polyatomic ion (poly- means many) or a radical.

33. The radical in the previous example is known as the permanganate ion, and is written as MnO 4 -1. You may have heard of other radicals eg carbonate (CO 3 -2 ), bi-carbonate (HCO 3 -1 ), hydroxide (OH -1 ), sulfate (SO 4 -2 ), etc. Most of the radicals that we will look at this year are negative ions. There is one positive radical we will encounter ie the ammonium ion (NH 4+ ).