IP Science - Q&A

[Verysuperkiasu]

Belle2011:

I am surprised that three O level textbooks are listed in the sec 1 booklist. I am kiasu but not to this stage of buying O level stuff now.

I am also shocked to see O level texts and for Geog, they actually start from sec 3. Now I'm getting nervous.... dont know whether ds can survive or not.

But it's comforting to know he's reading up not just the texts but search the web as well on related topics.

[tisha]

Verysuperkiasu:

tisha:

P.S: Sorry, I'm discussing 'O' science. Pls let me know if you want me move the discussion to a seperate thread.

No prob...Tisha, no need to move discussion to another thread. I suppose there will be some overlap between O levels and IP prog. We can share and discuss.

Thanks verysuperkiasu.
[quote]As for the solar system, I suppose it's more like general knowledge. Not quite sure why it was taken out of the syllabus @ psle though. I remember when I was in secondary sch, solar system was taught in Geography, not science. [/quote]You are right, it is indeed in the geography book 'EARTH our home. Thanks for pointing out.
[quote]As for biology, maybe they are using notes, not text bk. For RI, I didn't see any History text book either. [/quote]Yeah, maybe.
We do have a book for history as well. Singapore : A settlement to nation.[quote]By the way, which sch is your ds going to ?[/quote]DS is going to SJI.

[tisha]

Belle2011:

I am surprised that three O level textbooks are listed in the sec 1 booklist. I am kiasu but not to this stage of buying O level stuff now.

O level text book need not mean all Sec4 stuff will be taught in sec 1. I think it is more like reference guide for the secondary years. Just like lower block upper block text books for primary. Certain topics will be selected for each year/semester.

[Verysuperkiasu]

[quote=\"tisha\"]

You are right, it is indeed in the geography book 'EARTH our home.
[quote]

That's the same text book RI is using for Geog.
How about Chemistry and Physics @ SJI... is it Chemistry Insights and Physics Insight (Pearson Longman) as well?

[Verysuperkiasu]

Ds has a chemistry question…


He said he knows how to get valency of simple ions - like potassium K has a valency of 1+ due to its electronic configuration of 2.8.1 hence need to get rid of 1 electron.

But he doesn’t know how the valency of polyatomic ions like CO3 and NH3, etc are derived. In my sec sch days, I just memorized the valencies of these polyatomic ions. Now when my ds asks me, I don’t know how to explain.

Anyone can help to explain?

[tisha]

Verysuperkiasu:

tisha:

You are right, it is indeed in the geography book 'EARTH our home.

That's the same text book RI is using for Geog.
How about Chemistry and Physics @ SJI... is it Chemistry Insights and Physics Insight (Pearson Longman) as well?

The science text books used in SJI are :
Physics Matters for GCE 'O' Level (*) Marshall Cavendish.
Chemistry Matters for GCE 'O' Level (*) Marshall Cavendish.

[Verysuperkiasu]

tisha:

Verysuperkiasu:

[quote=\"tisha\"]
You are right, it is indeed in the geography book 'EARTH our home.

That's the same text book RI is using for Geog.
How about Chemistry and Physics @ SJI... is it Chemistry Insights and Physics Insight (Pearson Longman) as well?

The science text books used in SJI are :
Physics Matters for GCE 'O' Level (*) Marshall Cavendish.
Chemistry Matters for GCE 'O' Level (*) Marshall Cavendish.[/quote]Then it's different then, ds is using

Physics Insights O level
& Chemistry Insights O level

But I guess they cover the same thing.

[twilight]

Verysuperkiasu:

Ds has a chemistry question.....


He said he knows how to get valency of simple ions - like potassium K has a valency of 1+ due to its electronic configuration of 2.8.1 hence need to get rid of 1 electron.

But he doesn't know how the valency of polyatomic ions like CO3 and NH3, etc are derived. In my sec sch days, I just memorized the valencies of these polyatomic ions. Now when my ds asks me, I don't know how to explain.

Anyone can help to explain?

O almost always has a valency of -2. C can be +4 or -4 but in this case, it is +4 because even in polyatomic ions there is almost always + and -. Therefore the charge of CO3 would be +4+3(-2)=-2
Similarly for NH4 (btw it's NH4. NH3 is a neutral molecule), H will be +1. -1 valency for H is usually for organic compounds. N will be +5 or -3. In this case it will be -3 due to it being H+. So charge of NH3 is -3+4(1)=+1

[Verysuperkiasu]

twilight:

O almost always has a valency of -2. C can be +4 or -4 but in this case, it is +4 because even in polyatomic ions there is almost always + and -. Therefore the charge of CO3 would be +4+3(-2)=-2
Similarly for NH4 (btw it's NH4. NH3 is a neutral molecule), H will be +1. -1 valency for H is usually for organic compounds. N will be +5 or -3. In this case it will be -3 due to it being H+. So charge of NH3 is -3+4(1)=+1

Thanks, Twilight! I didn't know valencies of compounds can be added like that. I always thought it should be explained in terms of electron transfer or sharing of electrons. What you had just demonstrated seems much easier to explain to my ds. :thankyou:

[twilight]

Valency is essentially based on the transfer of electrons required to obtain a noble gas configuration, giving rise to ions.

-2 would mean gaining 2 electrons, causing the ion to have a -2 charge. The overall charge of the polyatomic ions is based upon the number of electrons transferred and the nett charge it has. For example, NaCl has +1 from Na and -1 from Cl, causing it to have a 0 nett charge and therefore it is a neutral compound and not an ion.