Chemistry Tutorial 2.02d: Basics Of Formula Writing

[MrRemixESO]

Thank you Boss.......You forced the information in the head. Awesome teaching

thanks again

[cessnalova]

After trying to understand this for a week with my teacher, i now get it by the first time i watched this!

[Boxrag]

WHY COULDN' MY CHEMISRY TEACHER EXPLAIN THINGS AS CONCISE. EVERYTHING MAKES SENSE.

[madformaddysmaddies]

thank you very much sir!!! I am in 4th grade and am interested in chemistry, and you made formula writing very clear to me, and increased my interest in the subject.Thanks to you, I can manage to get and secure great grades!!Thanks! XDXDXDXD

[trinxie000]

very helpful.. thanks :D

[bonsalakot]

the most easiest way is to use the criss-cross method..question isn't that Al(O2)3 is this right? Al(O2)3 and Mg(N3)2?

[MarkRosengarten]

@bonsalakot No. Al2O3 and Mg3N2. O and N are diatomic only when by themselves. When in a compound, use the charges listed.

[bonsalakot]

@MarkRosengarten oh i see thanks.

[bonsalakot]

@bonsalakot Uhmm isn't that when a polyatomic ion is taken for more than once, you need to right a parenthesis after that write the frequency occurrence as a subscript. is this right? you know when you read the formula Aluminum quantity oxygen 2 quantity three?

[rrrlightsauri]

thanks2x .......u save my life.. i was able to understand this lesson... hehehehehe my teacher assign me to report this topic.... thank you!!!!!!!!!!!!!!!

[TheFrimond]

why is Al2O3 named as aluminum oxide not aluminum trioxide?

[MarkRosengarten]

@TheFrimond A few reasons:

1) Al2O3 is ionic. Ionic compounds do not use the prefix system. Granted, Al2O3 has a pretty high covalent character compared to most ionic compounds but the rule still applies.

2) There is only one possible way that aluminum and oxide can form a compound. If there more than one way, as with iron and oxide, then a Roman numeral would be used to indicate the metal ion's charge. Fe can be +2 or +3, so...

Continued on the next reply

[MarkRosengarten]

@TheFrimond FeO (where Fe has a +2 charge) is called iron (II) oxide and Fe2O3 (where Fe has a +3 charge) is called iron (III) oxide. Al can only be +3, so AlCl3 is aluminum chloride, Al(NO3)3 is aluminum nitrate and Al2O3 is aluminum oxide.

[ron13rojo]

because of you, sir.. you made my grades increase!! thank you very much. :)

[MarkRosengarten]

@ron13rojo You made your own grades increase! You made the conscious effort to find help, and you found it! While I am glad that I could be of service to you, YOU looked, YOU watched, YOU understood and YOU improved! :) Congratulations!

[TheKulsoom110]

u r a logical guy mr mark. thanks

[angryDAnerd]

I am VERY impressed by how simply and logically you can explain this stuff. Your descriptions and examples allow me to understand very easily. Thank you!!!

[kamstergtohello]

You are the Best!!

[PatrickNaro]

Thankyou so much that helped a ton

[XHUMBITO1]

dude, you are great.

[xToXiicxT3RRoRx]

its easyier to swap them arround

[MarkRosengarten]

@xToXiicxT3RRoRx Yes, but it doesn't always work. It also doesn't explain WHY the formula is the way it is. Easier sometimes works, but it isn't always better to start. Once you understand WHY you swap them, then swap to your heart's content! :)

[xToXiicxT3RRoRx]

@MarkRosengarten well how i learnt them in school is the number beside the element shows if it is positive or negitive and how many more protons or electrons it has extra, and also it tells you how many bonds it needs to make a full outer shell then you swap them over and thats your formula

[MarkRosengarten]

@xToXiicxT3RRoRx That technique doesn't work for Ca+2 and O-2, Al+3 and PO4-3 or Pb+4 and SO4-2. You would get Ca2O2, Cl3(PO4)3 and Pb2(SO4)4. Your explanation really is an excellent one, but since it doesn't work in all cases, I like to give this method and then let the students figure out the crossover method for themselves...which they inevitably do.

[xToXiicxT3RRoRx]

@MarkRosengarten well sure for your way would it not be for Ca+2 and O-2 add them together gives you 4 them for Ca+2 you need 2 2's to make 4 and for O-2 you need 2 2's to make 4 which gives you Ca2O2 then you can simplify down to CaO

[MarkRosengarten]

@xToXiicxT3RRoRx You are absolutely correct...once you add the simplification technique.

[xToXiicxT3RRoRx]

@MarkRosengarten yes well both ways are very good i will probabily try both to make sure i get it right in the exam if i have extra time also if you had say something like Pb+4 and O-2 which gives you Pb2O4 how could you simplify that is it PbO2

[xToXiicxT3RRoRx]

@xToXiicxT3RRoRx And also with the way i learnt it you can tell how many bonds it can make from the periodic table by looking at what group it is in and then working out how mang bonds it can make to get a full outer shell then switching over and then simplifing. How can you tell if an element is a negative 2 or a positive 2 in your way?

[xToXiicxT3RRoRx]

@MarkRosengarten and also whenever you have the two elements is it only after they bonded you can write the formula for them please wb

[MarkRosengarten]

@xToXiicxT3RRoRx Yes, that is correct. Many elements have allotropes...where the molecular structure of the element can vary, but it is still just one element. A compound MUST contain two or more elements bonded together either ionically or covalently or some combination of the two.

[youngday713]

Ya i get that, my chem teacher really didn't explain why you do it, I just thought you know after people understand the reasons they could do that. But thanks for the video I really enjoy it

[youngday713]

jus a suggestion cross multiply the charges and bring them down to oppisite sides. Al+3 and O-2 if you cross and drag down it becomes Al2 O3

[MarkRosengarten]

@youngday713 That shortcut does work, but I would rather people understand WHY you are doing it instead of just going through some mechanical process.

[MsLashae123]

Wow thanks

[BrownFlip7852]

this just might help me pass my exam this morning

[spicysoul93]

can someone please put subtitle on the video please? and the whole other units too. thank you so much and i would appericiate it.

[MarkRosengarten]

@spicysoul93 That would take me about a year to do with the hundreds of videos I have up here. That would be a year of doing absolutely nothing but working out subtitles, re-editing the videos, reuploading them and reordering them. It's not a job I'm going to do, I apologize for that. I do the best I can with what I have to work with and the time I have to work with.

[PeaceISL]

THANK YOU. THANK YOU !

[Requiemelle]

I am eternally grateful =w=

[realmickoy]

how would you write these in word form

[rhenn11]

@realmickoy: NaCl is Sodium Chloride. Basically, you take the name of the Metal Element, then take the name of the Non Metal Element + the suffix ide. There are other rules to be followed so pay attention to them as you continue studying about Chem. Nomenclature, but what I said is really the...er...basics? 

[punzalan13]

Thanks! God Bless!

[gokue55555]

dankie jou koeilie

[merceditas2009]

makes sense, finally.

[TheJabarkhel]

this make some sense

[devinasc]

thank you soooo much such a big help! ive been lost for months!

[Busarocks]

Awwsooooome!!! After 25 years of not understanding chemistry I "finally" see the light! Thank you for this wonderful explanation!!!!

[budhaballah]

holy shit i have a chemistry exam tomorrow and because of this it actually makes sense

[TheLolamabel]

thankyou so much! chemistry test tomorrow, and I finally understand! thankyou!!

[Andeeluv]

Thank youuuU!!!!!! I feel so much better now!!!! Im finally starting to get this chemistry thing!!!

[DrRythm]

Aluminium...not Aluminum...grrrr.

[Mizhki]

Thank you I have learnt something

[MrAkhan14]

thanks man helped me out big time

[lysolluvswindex]

THANKSSS!!!!

[crpr21]

so helpful

[vaneg12]

you seriously saved my life.. THANKS!

[PmasterFunk9]

Very Helpful thanx

[deaneden79]

THANK YOU THANK YOU THANK YOU!!! Feels like I'm trying to learn Japanese or something but your explanations are so logical. Thanks again!! Understanding the basics of organic chemistry feels so difficult.