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- @PlaySoundFile ADB40_01.wav
- @AtGraphic 120,11
- @Picture ADB40_01.bmp
- @At 135,142
- Each element in the periodic table has a valency which is a
- number based on the number of electrons that it donates or
- shares when it bonds.
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- @Prompt
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- @PlaySoundFile ADB40_02.wav
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- @At 138,210
- When sodium reacted with chlorine it donated one electron
- so it has a valency of + 1.
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- When chlorine reacted with sodium it gained one electron so
- it has a valency of -1
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- @PlaySoundFile ADB40_03.wav
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- @AtGraphic 130,200
- '@Picture ADB40_02.bmp
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- @At 134,280
- The periodic table can be used to act as a guide to the valency
- of elements. Sodium with itÆs one extra electron is in group
- 1 and so it has a valency of +1.
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- @At 139,340
- What is the valency of potassium?
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- '@Answer 1
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- '@Feedback Wrong
- '#bNo#b, potassium is also in group 1 with one extra electron in
- 'its outer shell so it too has a valency of +1.
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- '@Animation BoseGrim
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- '@Feedback Correct
- '#bYes#b, potassium is also in group 1 with one extra electron in
- 'its outer shell so it too has a valency of +1.
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- @Prompt
- @At 136,367
- Chlorine, however, is in group 7 when it bonds with sodium
- it accepts an electron.
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- What is the valency of chlorine?
- '#[N]
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- '@Answer -1
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- '@Feedback Wrong
- '#bNo#b, although chlorine is in group 7 it does not give away 7
- 'electrons when it bonds, it accepts one electron which gives
- 'it a valency of -1.
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- '@Animation BoseGrim
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- '@Feedback Correct
- '#bYes#b, chlorine is one electron short so it has a valency of -1.
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- @Prompt
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- @PlaySoundFile ADB40_04.wav
- @At 130,324
- Using the valencies you can see straightaway that only one
- chlorine is required to bond with one sodium to produce the
- compound sodium chloride.
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