Ionic Bonding L.O.

1. 31/08/2014 • Ionic Bonding • L.O. • I can predict if a compound has ionic bonds and know how to work out the formula of a compound that has ionic bonds. 23:51

2. 1st Shell: 2 electrons 2nd Shell: 8 electrons 3rd Shell: 8 electrons How Many Electrons per Shell? • Each shell has a maximum number of electrons that it can hold. The maximum

3. Protons Electrons Atoms Lose 1 electron Gain 1 electron Protons Electrons 1+ ion Protons Electrons 1- ion Ions and Electron Structures • Ions are atoms that have either extra electrons added or electrons removed. So in ions the number of electrons no longer equals the number of protons

4. Lost 1 e- Lost 2 e- Lost 3 e- Positive Ions Ions usually have OUTER electron shells that are either completely full or else empty + • These are ions formed by the atom losing one or more electrons. • They are called cations. This is because during electrolysis they move towards the cathode. (Or because they are “pussytive”!). • The charge on the ions is equal to the number of electrons that the atom has lost. • In equations the charge is usually shown above and to the right of the symbol. (E.g. Mg2+ ). It is nearly always metal atoms that lose electrons 2+ 3+

5. Na+ Na Electron lost The Electrons in a Sodium Ion 23 Na 11 In the sodium atom Atomic number = number of protons = 11 Number of electrons = 11 Bye! Electron arrangement: 2.8.1 (Incomplete Shell) Electron arrangement: 2.8 (Full Shells)

6. Bye! Mg2+ Mg Bye! 2 electrons lost The Electrons in a Magnesium Ion 24 Mg 12 In the magnesium atom Atomic number = number of protons = 12 Number of electrons = 12 Electron arrangement = 2.8.2 (Incomplete shell) Electron arrangement 2.8 (Full Shells)

7. Activity • How many electrons? • How many electrons in the first shell? • How many electrons in the second shell? What electron arrangement? 1st Shell = 2: full Li+ Li 2nd Shell = 1: not full How many electrons to lose? New electron arrangement? Include a diagram The Lithium Ion 3 7 Li 3 2 1 2.1 1 Bye! 2.(0)

8. Activity • How many electrons? • How many electrons in the first shell? • How many electrons in the second shell? What electron arrangement? 1st Shell = 2: full B3+ B 2nd Shell = 3: not full Bye! Bye! How many electrons to lose? Bye! New electron arrangement? The Boron Ion 5 11 B 5 2 3 2.3 3 2.(0)

9. Gain 1 e- Gain 2 e- Gain 3 e- Negative Ions. - • These are ions formed by the atom gaining one or more electrons. • They are called anions. This is because during electrolysis they move towards the anode. • The charge on the ions is equal to the number of electrons that the atom has gained. • In equations the charge is usually shown above and to the right of the symbol. (E.g.. O2- ). It is nearly always non-metal atoms that gain electrons Ions usually have OUTER electron shells that are either completely full or else empty 2- 3-

10. F F- 1 electron gained The Electrons in a Fluoride Ion. 19 F 9 In the fluorine atom Atomic number = number of protons = 9 Number of electrons = 9 Electron arrangement: 2.8.7 (incomplete shell) Electron arrangement 2.8.8 (Full shells)

11. S S2- 2 electrons gained The Electrons in a Sulphide Ion. 32 S 16 In the sulphur atom Atomic number = number of protons = 16 Number of electrons = 16 Electron arrangement: 2.8.6 (incomplete shell) Electron arrangement 2.8.8 (Full shells)

12. Activity • How many electrons? • How many electrons in the first shell? • How many electrons in the second shell? What electron arrangement? 1st Shell = 2: full O O2- 2nd Shell = 6: not full How many electrons to gain? New electron arrangement? The Oxide Ion 8 16 O 8 2 6 2.6 2 2.8

13. Working out Formulae Work out the formula of :- • sodium chloride • magnesium oxide • sodium oxide • magnesium chloride

15. Drag the words at the top to their correct places in the sentences.

16. Word check

17. Which of the following is not a sub-atomic particle? • Proton. • Isotope. • Neutron. • Electron.

18. The element Cobalt has a relative atomic mass of 59 and an atomic number of 27. Which of these is a true statement about each neutral cobalt atom? • It contains 59 neutrons. • It contains 27 electrons. • It contains 32 protons. • It contains equal numbers of neutrons and electrons.

19. The Periodic Table displays iron as shown below. This indicates that Fe atoms: • contain 56 neutrons. • contain 30 electrons. • contain 26 protons. • contains more protons than neutrons. 56 Fe 26

20. Bromine consists of a mixture of two isotopes: Bromine-79 and Bromine-81 • Which of the following is true: • Both isotopes contain 35 protons. • Bromine 79 contains 46 neutrons. • Bromine 81 contains 44 neutrons. • Bromine-81 is more reactive than bromine-79. 80 Br 35

21. Natural boron consists of approx. 20% boron-10 and 80% boron-11. • What will the relative atomic mass of natural boron will be? • 10.0 • 11.0 • 10.5 • 10.8 ? B 5

22. Which answer best describes the shell arrangement of the electrons in a sodium atom? • 2,8,1. • 2,2,7. • 2,8,8,3. • 2,8,8,1. 23 Na 11

23. Which answer best describes the shell arrangement of the electrons in an oxygen atom? • 2,8,6. • 2,8,8. • 2,8. • 2,6. 16 O 8

24. 14 N 7 40 Ar 18 A B C 40 Ca 20 D 27 Al 13 • Which of these elements will have electron shells that are either full or empty (i.e. not partially full)?

25. Which answer best describes the shell arrangement of the electrons in an oxide ion O2-? • 2,8,6. • 2,8,8. • 2,8. • 2,6. 16 O 8