The Periodic Table

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Mithoron

00:07

Well bye guys, g'night

getafix

G'night @Mithoron

Ixrec

01:03

would "Why is the Delisle temperature scale 'backwards'?" be a good question for this site?

Jan

What is the Delisle temperature scale?

Ixrec

Delisle scale

The Delisle scale (°D) is a temperature scale invented in 1732 by the French astronomer Joseph-Nicolas Delisle (1688–1768). Delisle was the author of Mémoires pour servir à l'histoire et aux progrès de l'Astronomie, de la Géographie et de la Physique (1738). == HistoryEdit == In 1732, Delisle built a thermometer that used mercury as a working fluid. Delisle chose his scale using the temperature of boiling water as the fixed zero point and measured the contraction of the mercury (with lower temperatures) in hundred-thousandths. Delisle thermometers usually had 2400 or 2700 graduations, appropriate...

Loong

@Ixrec maybe. You could also try hsm.stackexchange.com

Jan

I would say no. Physics or hsm.

Ixrec

HSM makes sense, thanks

Loong

01:10

@Ixrec is that an offshoot of the Fahrenheit discussion in Mos Eisley?

Ixrec

that is what got me browsing Wikipedia articles on temperature scales, so I guess so

Loong

:-)

getafix

01:22

What's HSM stackE?

Oh okay nevermind found it

Jan

@getafix Istry of signs and mafs ;)

getafix

Yeah found it :). How goes @Jan?

Jan

Excuse the terrible pun, but my answer is 'off to bed' ^^' (It's half two in the morning here D=)

WDUK

I still don't understand all that well =/

I am so screwed for my assignment :P

getafix

@Jan 'night then

@WDUK what don't to understand?

WDUK

01:37

i have two molecules that i have to determine if they form a covalent or ionic bond, then also have to explain why they have different melting temperatures

for room temp at 1 atmospheric pressure

i could google what their bonds are but i wont fundamentally understand how to work it out myself which bothers me greatly

getafix

I see.

WDUK

safe to say i won't be doing second year after this

getafix

Okay. So a bonds ionic character is a) determined by the diff. In electronegative of the participating species.

But it's not the simple. You need I check somethings else too

WDUK

well see the book never mentioned that term "electronegative"

at any point

getafix

en.m.wikipedia.org/wiki/Fajans%27_rules

Read up on that

WDUK

01:42

what values are considered high/low ?

seems to range from 1 to 3

getafix

I don't know if there's a more modern formulation that replaces Fajans rules but they work well

Electronegativity values are tabulated read up on the Pauling scale

WDUK

so from that wiki

Al3 S2 would be ionic

because it would be Al+3 and S-2

giving only +1 charge

or am i confusing two seperate things

getafix

Be right back, sorry doing something

WDUK

no probs :)

1 hour later…

getafix

03:14

So yeah coming back. I would expect it to have ionic character..,saying something is really completely covalent or ionic (or so I've been told) is hard

If you look it up some data..it has a melting point of 1370 K

In its crystal str. the sulphide ions form a hcp lattice and Al occupies the tetrahedral holes.

The main idea is a) if the difference in electronegativities is large then bond is ionic

b) if the anion is large, and it's electron clouds are polarisable..you get more covalent character

CopperKettle

04:16

@getafix Oh, it is I who am the dense one. (0: I should read more. I see. When Cl meets a Br salt in solution, it seeks to supplant Br- and become Cl-, and this makes the whole solution warmer.

Abhirikshma

so can it be correctly said that in the compounds where the ions are similar in size are the least covalent ?

CopperKettle

I wonder if it could be said that two lovers of Japanese animation have a kawaii bond. If one loves animation more, then it's polar kawaii bond.

CopperKettle