/sci/ - Science & Math

P/(x + y.(y/x)^2) simplifies to P.y/x(x+y)

please explain how its fucking bugging me

>>7198506
Calcium is the most abundant metallic element in the human body (in the form of Ca2+ salts). The human body contains around 30.0 moles of calcium. How many grams of calcium is this?

>>7198511
sorry, thats not even written right

P/(x + y.(x/y)^2 ---> P.y/x(x+y)

>>7198512
30 times its molar weight (the number next to it on the periodic table)

30 x 40.078 = 1202.34g

>>7198506
The correct electron dot symbol for a potassium atom is

>>7198519
Why are you asking a question that can be answered with google images

>>7198518
thank u god sir!

>>7198506
how to you find out the number of valence electron of an element?

>>7198514
So first your (x/y)^2 becomes x^2/y^2. Then y.(x^2/y^2) is yx^2/y^2 which is x^2/y. So you now have P/(x+(x^2/y)). Multiply numerator and denominator by y and you have Py/(xy+x^2) which is the same as Py/(x(x+y)) by taking out the common factor of x.

>anon has a high school chem assignment
Reminder that if you are under 18 you don't belong on this website.

>>7198528
no really I'm 20 and I'm studying geology in university but i found it very difficult without having done any sort of chem back in high school

>>7198527
Oh shit, i see where i was going wrong. I got to P/(x+(x^2/y)) and was just bringing the y up from the denominator the the numerator without multiplying it in the denominator as well. Fucking long day with a lot of exponents. Thanks m80

>>7198533
okie dokie.

Number of valence electrons in an element is the number of electrons in its outer shell that can contribute to a chemical reaction.

How many of the elements do you have to know? If its just the first 20 then its simple, its just its row in the periodic table. once you get to metals its gets a bit more complicated. For the first 20 you just look at its column in the table. As a rule of thumb, column 1 has 1, 2 has 2, ignore 3 to 12, theyre complicated. 13 has 3, 14 has 4 etc etc.

>>7198539
oh, and 18 has none, not 8. Full outer shell means no valence electrons.

>>7198539
can u give me examples? i.e. fluorine?

>>7198543
ok.

Quick tip, get a periodic table and print it off, or at least save it. Seriously helpful, this one is pretty good as it has the molecular weight of each element (the weight of 1 mole of it)

Fluorine: F is found in the 17th column and the second row of the periodic table, and is the 9th element. 2 ways to figure out the valence electrons.

1. Its column. F is in column 17. This would mean that it has 7 valence electrons. The same can be said for all other element in column 17 (Cl, Br, I, At).

2. Its periodic number. Not sure if youve learned this, but atoms (at least at the level you need to know) have electrons that fill its shells. The first shell that is filled is closest to the atom and can fit only 2 electrons. The second and third shells can both fit 8 electrons. Fluorine is number 9, meaning it has 9 protons. This means that a stable atom of fluorine also has 9 electrons. 2 fill the first shell, then there are 7 left over. They dont fill up the outer most shell, so they are valence electrons. Chlorine for instance would also have 7 valence electrons, as it fills up the first shell of 2, then the second shell of 8, and then 7 in the next shell (17 electrons for 17 protons.

Im sorry if this is long and shitty but Im not too sure what understanding of chem you have so im going pretty slow

>>7198548
wow that is really really helpful thank u anon!

>>7198569
how should u approach questions like this?

I know of bonding types but how to u count?

>>7198506
How many moles of oxygen (O2) are present in a cylinder of 25.0 liters at a temperature of 0 °C and a pressure of 1.00 atm?

>>7198506
Guys how the fuck is:

a^2n-3 a^3n-2 a^2-3n= a^2n-3

>>7198573
Holy shit this one is impossible wtf

>>7198573
FUCK
I'm a Chem undergrad and I can't get this shit, can someone help me? Better yet, can a Math guy who knows graph theory help me prove that this configuration is impossible?

>>7198573
Holy shit I can't solve this thing here, help me I'm going gran autismo

>>7200178
What if it's a zwitterion?

>>7200178
that should be a benzene ring, no?

make that bordering nitrogen oxygen bond from a cyanide to a nitric oxide?

>>7198581
use PV=NRT
assume its at STP
this is chem 1 faggot

>>7200178

>>7200271
first yeah
second nah

>>7200271
b-b-b-but there is no oxygen

>>7200242
My guess also, but this doesn't seem logical, this is probably OP's intro to organic chem, you won't come across zwitterions yet.

>>7200281
and the imidazole's nitrogen's lone pairs becomes the double bond to carbon with 3 bonds. So now it's aromatic?

i'm going to bed

>>7200295
it's a conjugated system as drawn, best you gonna get it, call it night

>>7200284
I did zwitterions in A-level chem. Nothing advanced, obviously, but it went along with the intro O-chem stuff we did. I suppose you don't need anything more than the definition to work it out (through tedious testing).

>>7200295
Autismo here, I guess this is as good as we're gonna get. Christ.