Chemistry

Why does the VIIIB group have 12 elements?

Hi,
so I got this question that you can read above (it is about the periodic table and its groups). When I was trying to find the answer I basicaly bumped only on one page that explains it. It is important to note that this system is old one and nowdays you only number these groups from 1-18. If you want to read the answer from first hand go here: 1)

So in the new system they are not in the same group, but why were they there before?

The groups are made by comparing the physical and chemical characteristics of the top electron shells. This special VIIIB group are the collumns under Fe, Co and Ni which makes it quite unusual.

Basicly as you move across the periodic table, different oxidation states are more and more stable (in chemistry most things just want to get as stable as possible).

Those elements that have similar stable oxidation states are then put together. Take for example halogens. Those are the very very reactive elements next to noble gases.

Halogens in periodic table.

All of them will have oxidation number -I (most of the time). This puts them together. Transition metals are much more difficult to grasp with their d-orbitals. As you have seen in my other post they make some problems. The oxidation numbers for them are not very clear. Iron can be in II as well as III but generally these twelve/nine elements are occuring in the similar ones. Oxidation for these elements is actually almost always 2 or 3, this is especially true for nickel.

Dragallur

There is just an empty space

Hi,
here is the second season of facts I created, enjoy:

1) The highest ionization energy for copper is over 1,000,000 kJ/mole, one mole of copper is approximately 63.5 grams and the energy taken by this process is equivalent to the chemical energy of 160 L barrel of oil. This equals also to 250 kg of TNT.
2) The longest protein known is Titin: C169 723H270 464N45 688O52 243S912
3) The thickness of soap bubble ranges from 10-1000 nanometers.
4) One Japanese engineer memorized 100,000 digits of pi.
5) Marie Curie was the first woman to get Nobel prize in 1903. She is also the only woman that got 2 Nobel prizes and this happened to only three other people and two organisations. Also her daughter Irène got Nobel prize with her husband.
6) Einstein was asked to be the first president of Israel, he refused.
7) Four new elements have their names, the most massive (proton num. 118) is called Oganesson.
8) Carbon has the highest melting point and that is 3823 K. The highest boiling point is for Rhenium and it is stunning 5869 K!
9) Yes I am serious, if you fold regular piece of paper 42 times you will get it on a Moon. (42? This is no coincidence!)
10) Everything is just a space.

Dragallur

PS: This was automatic post, I will not be able to respond to comments until Monday.

Huge mistake in valence electrons

Hi,
finally today I am going to explain the huge mistake in valence electrons of most metals. This is a mistake that I guess that most teachers learn and you will find it all around the internet, if it is not there then it is probably not explained accurately.

When people usually write out the electron configuration of atom or ion they use the quantum number of the atom to get it and then it depends if the atom is in s,p or d part of periodic table.

s,p,d,f elements

Those atoms have valence electrons in the respective orbitals.

Oxygen for example is p-atom. It is in second period so the highest orbitals will have the number 2. All p-atoms have full s-orbitals and oxygen has four spare for p-orbital.

O: [2s]2 ; [2p]4 (lets write it like this, four electrons in p-orbital and two in s.)

This is the usuall way and it works quite well, except when it does not.

The problem comes with transition metals (which is most of the table), those are metals in the d-group, the ones in the middle. Particularly you will see the mistake with 6th and 11th collumn. If you would write the configuration for Chromium for example it should go like this:

Cr: [4s]2 ; [3d]4 (d-orbital is always -1)

But whoops! There is mistake! Why? Because you are assuming that the energy of the orbitals continues to go like this, that 4s orbital has lower energy than 3d. This happens not to be true in this case, generally the difference is very small, the nucleus changes as you add protons and neutrons to it which may change the balance. Now in this case it does change the balance, I do not understand the mechanics behind it so you will have to deal with this. The right configuration of Cr is this:

Cr: [4s]1 ; [3d]5 (the number of electron remains the same)

Also 4s is close so it is not very stable to put there one more electron when you have nice free 3d orbital.

This problem occurs again with molybden but not tungsten and seaborgium! This is because the effect is not strong enough, the atom looks different and so on. As I mentioned this mistake is also in 11th collumn which is copper, silver, gold and roentgenium. These guys have full d-orbital and only one electron in s-orbital.

Of course if you create ions you will bump into this again. Vanadium which is right next to chromium has the problem again,

V5+ ; V4+ 3d1 ; V3+  3d2  ;  V2+  3d3 ;  V+  3d4  ;  V   3d34s2

Sometimes this whole problem is explained as that d-orbital is more stable when half full or full completely. This is false since clearly it does not explain tungsten which behaves normally.

If you get to write configurations of transition metals check out this page, it will show you exactly how it looks like and you wont do mistake. Also I used these pages for the answer so check out these if you are not sure about something: 1) 2)

Dragallur

How radioactivity was studied

Hi,
today I want to write about radioactivity. It is rather new concept which is not very surprising as the process of radioactive decay is not very visible and the effects (on health for example) are not so clearly connected since they usually have long time span. Probably largest work done on this topic was by Marie Curie and her husband Pierre.

This is how radium dials looked like, cute!

Curie was from Poland. She had kind of difficult childhood since women were persecuted at that time in the east and it was hard for her to find place to study. Later on, she was able to move to Paris with her sister. There she met Pierre with whom she had two kids.

The first time she encountered with radioactivity was when she measured pitchblende [1] and uranium and how much radioactivity they  were “giving off”.

She expected that pure uranium would be much stronger but this was not what happened, what she found was exact opposite. Later on, thanks to this she found out two new elements: Polonium and Radium.

At this time it was not yet known that you can get pretty easily cancer by being close to radioactive stuff. Curie and Pierre were buying tens of kilograms of pitchblende to do their research and prove those two new elements since lot of other scientists were kind of sceptic about it.

In November of 1898 they extracted compound that was 900x more radioactive than uranium, you can see where this was going.

In 1902 it was announced that one decigram of radium chloride was succesfully isolated.

Four years later Pierre died when wheel of carriege run over his skull, this was because of the effects of radioactivity, at this point he was not really able to use his hands, they were pretty much destroyed by the pitchblende and his whole health was in very bad state.

In 20′ it started to be more and more clear that there is something wrong with the stuff. There was actuall factory that painted dials with radium (not pure of course), this is because it glows nicely and everyone liked it. The brushes that were used for this had to be kept sharp and this was done by lips. For this work about 4,000 people were hired, the so called “Radium Girls” was a group of women that also painted for fun their nails, face and teeth, noone knows how many sacrifices this caused.

Dragallur

[1] Pitchblende is mineral that is radioactive since there is uranium and other heavy elements. Lot of miners in extreme conditions died because they were mining it.

Your phone is NOT killing you

Hi,
today I want to write about ionizing and non-ionizing radiation and also mobile phones as serial killers.

When somebody says radiation they mean electromagnetic radiation. Light is of course an electromagnetic radiation but only small part that we can see.

Visible light makes only very small part of whole spectrum.

The energy of light is connected with its frequence, as it rises (to left) energy increases as well. Gamma rays are the most energetic part of spectrum, they appear in radioactive decay and the are also created in Sun. Radiowaves on the other hand have enormous wavelength and very small energies, this is very good because it means that they are easy to create and also not harmful to human.

When we talk about radiation we can say that it is either ionizing or non-ionizing. If it is ionizing it means that it can create ions. Ions are either positively or negatively charged atoms, ions are created when they get or lose an electron which happens when photon hits the electron, but not always. If the energy of the photon is high enough then it will happen (ionizing) but if it is not the nothing will happen (non-ionizing).

How does this corresponds to your phone?

Well there have been some studies that showed that frequent phone users had higher chance of getting brain tumor. This would be caused by the photons that are transmitted from your phone. They should apparently hit DNA and other stuff in your cells and by ionizing these atoms, make change and possibly develop cancer.[0]

The radiation that is used in your phone is with the wavelength of tens of centimeters which means something like low radiowaves. Photons in this part of spectrum would not be able to knock electrons from atoms at all [1].

While for example study from Sweden showed that brain tumors and phone usage correlates, the study was not so well made. The problem is that you need gigantic sample since brain tumors are very rare (3/100,000 people). In short, the best thing you can do is to look on the number of brain tumors before “everyone” started to use cell phone and compare it to the number brain tumors right now…

SPOILER AHEAD

There is no correlation whatsoever!

Dragallur

If you want more detail about the studies and so on, check out these two videos:

[0] I was just thinking that if radiowaves cause cancer than we should probably be much more conserned about ultra violet that is roughly million times stronger!

[1] Einstein got Nobel prize for finding the photoelectric effect which is basicly the knocking of electrons by photons. He found out that under certain frequency the atoms will not be ionized because the energy is not high enough (this critical point is different of course for different elements).

 

 

Why is HClO4 stronger than HClO?

Hi,
so this monday we had chemistry class again and because we are learning about halogens our teacher mentioned some acids and she explained why some of them are stronger than other. She got to the point of comparing HClO4, HClO3, HClO2 and HClO. She arranged them in this order in decreasing acidicity explaining why. As I found out over time, she is oversimplifying things, in this post I will try to show why they are in this order.

Perchloric acid 60 percent.jpg

Almost like water, the picture of perchloric acid. (HClO4)

So here we have four acids (to make it faster I will compare only first and last one). Both are same except that there are three more oxygens in HClO4 and the oxidation number of Cl is VII on the left and I on the right. Now this has to be the reason for different properties.

In all of those molecules Cl is the middle one, which means that all oxygens are connected to it with double bond, except one with only simple one which has hydrogen on the other side.

The picture shows the structure of these molecules.

So as you probably know water has what is called “dipole moment”. This is a term that is used for molecules that have partiall charge on one side and the other charge on the other side.

This has very interesting properties but what is important is that HClO4 has this too, and much more than HClO because there are oxygen ions which have charge of -II making chlorine in the middle of them a lot “ripped off” because there are those oxygens with higher electronegativity that are trying to get those electrons to get on the configuration of noble gases.

Now before the conclusion we must clear out the definition of acidic molecule. Such a molecule is acid when it is good at giving H+, so now the question is, why is HClO4 better in giving H+ than HClO?

So the key lies in what happens when these acids break up. When HClO4 becomes ClO4- there is not so much stress into getting the hydrogen back because delocalized electrons from the other oxygens [1] can ease it up making the molecule more stable while in HClO loses only one of two donors of oxygen making the molecule want it back a LOT.

Simply:

Electron withdrawal increases strength.

If you are not sure about this, ask me in the comments or check out the resources that I used.

Dragallur

Resources: 1|2|3|4|5|6

[1] Yes oxygens here have all two free electron pairs which are doing some wonders!

 

 

How did life arise?

Hi,
I bumped into this question when I was arguing over evolution and creationism. It is very favorite claim that life had to be made by God because humans were not able to create it from dead matter, rocks for example.

This is famous problem. It is true chemists were not able to create life when simulating the early time on Earth 3.6 billion years ago (this is for simplicity, it is kind of difficult to say when exactly life arose).

Now of course there are theories and one of them is the theory of primordial soup. This is theory that in the ancient ocean there were dissolved some basic molecules which we can find even on other planets (so we have proof for them that may have been here (and almost surely were)).

So as they are floating in the dead ocean there is some great radiation coming down and hitting these molecules. Also there is what is called “primordial lighting” which is the lighting that should be able to create more complicated molecules only by hitting ammonia, hydrogen and other stuff. It was proved that there should be monomers too. Those are simple organic compounds, such as lipids or proteins.

Primordial soup in can.

Chemists were able to create with some radiation and electricity even amino-acids. The last step was that we were able to create purines and pyrimidines, those are building blocks of DNA and RNA which is kind of important.

RNA and DNA, key components for modern living.

Nothing more, we were not able to create life, yet. What would the next step be? Something that is called replicator.

Replicator is any molecule or lot of molecules that are able to replicate itself. This is key. If we are able to create some kind of replicator from the primordial soup, we will take a giant leap forward, because then onwards evolution takes a place.

When replicator replicates it should make exact copy of itself like in asexual reproduction. But as good secretary makes roughly one mistake per page, even the replicator will eventually make a mistake. This is called mutation and it is either helping the organism or not. This process drives evolution even that only small part of all mutations may be helpful. Those who have good mutation will have more replicas of itself and eventually there will be only those which are better, this process will repeat in what is called evolution when after hudreds of millions of years you are standing here, originating from one simple replicator, as well as me, your class mates all other animals, bacteria and viruses. This was never observed but it should work like this.

In bottom you can see the LUCA, first original organism from which we originate!

 

So will we be able to create replicator? The problem with that is that only several laboratories over world are working on this. They are working on it only for about 100 years which is not much considering geological time.

While I did not see their laboratories I bet that they are working on small areas, maybe area of swiming pool and I found, I cite:

Liquid water covered much of the Earth’s surface by 3.6 (or 3.8?) Ga, but when before that it condensed from a dense atmosphere is undefined.

We can of course speculate on what “much” means though I would guess that we can start on reasonable 50% of Earth’s surface which is 255,036,000 square kilometers. When speaking about swimming pool I will take olympic swimming pool though I guess that the chemists work with much much smaller, they would not be able to control such a big area.

Imagine controling experiments on this thing!

It means that the Earth was able to use roughly 204,028,800,000 times bigger area than chemists not talking about the fact the oceans are deeper.[1] At the same time, there were couple of millions of years for this to happen compared to 100 in laboratory.

My point is that we maybe should not expect the life to rise in our laboratories, because if it does, life is much more probable that we thought[2].

Dragallur

PS: Do not ever argument by saying that Pasteur proved that life can not rise spontaneously, because he did not.

Read more: 1) 2) 3)

[1]Of course you could argue that in laboratory you can use lighting all the time and be purposeful with your selection of molecules.

[2]Maybe we should since our techniques improve and we are getting better in simulating and controling the environment of primordial soup.

When you could actually make money from alchemy

Hi,
yesterday I wrote about astrology and I also mentioned alchemy so I will continue with that.

So alchemy in reneissance was very real. It was a study with combination of chemistry, physics and medicine. There were two main things that alchemists cared about: Philosopher’s stone and the Elixir of life.

Alchemy was kind of connected to astrology because the known celestial objects for example were connected to various metals.

Sun – gold, Moon – silver, Venus – copper, Mercury – mercury :D, Mars – iron, Jupiter – tin, Saturn – lead.

Alchemists were strictly against adding another metal, why? Because they did not have enough planets!

Their quest simply was to take metal and transform it to the best form – gold. It was said that those metals normally “were in season (is this some kind of phrase?)” in Earth’s crust.

There was one way to get gold, Philospher’s stone also called Red lion.

The symbol of Philospher’s stone

That was hypothetical stone or red dust that if you mix with metal it will create pure gold. If you saw Harry Potter movie, this is used there in first part.

The second thing that was alchemist trying to make was the Elixir of life. Hypothetical liquid which should be able to cure any disease, even deadly one like cancer.

Across centuries people were also trying to find what was called: Emerald tables. Those were tables where all the important stuff for alchemy was hidden. Also as you can see the fourth best metal in the row was mercury. Since mercury is a bit poisonous some people died from it, I believe that it really fascinated people that something so dense is liquid, but I do not get why they had to drink it immediately!

There are two important people in alchemy of reneissance: John Dee and Edward Kelly, I will talk about them some other time though, look forward.

Dragallur

To read some more stuff: 1) 2)

 

Island of stability for dummies!

Hi,
island of stability is an area surrounded by lot of really fast decaying elements. Today I will write about island of stability which is on the other hand area with hypotheticly and relatively stable elements.

By area I do not mean some place. It is rather area in periodic table of elements extended for various isotopes.

The more heavy nucleus of atom gets, the easier and better for him it is to decay, potentially killing everything around, or at least giving some nice brain tumors. But then at some point, some of the elements are smart enough to stay stable, like a boss. Those are the elements in island of stability, this island is not very big and we can just guess its highest peaks.

The elements are much more stable because of the shape of their nucleus. The problem is that the nucleus becomes a bit deformed, even elliptical.

Anyway there is this thing called “magic number” which is a number of protons or neutrons which can lead to good shape which is stable, this means round normally. Such numbers are for example 2,8,20,28… 126. There are few other hypothetical (196,236…), elements which live on this island should have some combination of these numbers which would make them much much more stable than the stuff around.

For example Ununoctium which is the last known element has half-life of only 890 microseconds.

The island should come in proton number of roughly 120 and little bit more.

Picture showing the island of stability (white circle). The most stable elements could last for longer than an year.

There is even hypothetical second island. It would have to be around element 164. Who knows how many more theoretical elements there are before we will simply not be able to stick all these protons and neutrons together (not that we are sticking them).

Dragallur

 

 

Chemical bonds, part 2

Hi,
it has been more than month since I wrote about chemical bonds. It was easy post just an explanation to all kinds of bonds: covalent, coordinate, ionic, two days back I updated it so there are even polar and nonpolar bonds but what I want to look on right now are sigma, pi and whole other kinds of bonds. This is a different perspective, it is more kind of from inside. Again like few other chemistry posts I made this because our teacher in school as I found out did not learn us what I would say is interesting and maybe important.

So from the last post we know that atoms that are bonded together are bonded in different ways, usually this is just dependent on the electronegativity, or if it is metal or not. But then you can look in these bonds and sort them in other groups:

σ bond

σ is a sigma bond. This is the most basic kind. Bonds create when there is enough energy and the atoms are turned toward each other in right way. Always when there is bond, double or triple there will always be one sigma bond and it will be the first bond to create. This bond is also the strongest one. Sigma can form between s orbitals or two p orbitals or s and p or even two d’s. There are some more conditions about axis and so on but if you have a single bond between two atoms it always going to be sigma.

π bond

π is a pi bond. This is the second most common one and you can have more of them between two atoms. For example triple bond will be usually made up of one sigma and two pi bonds. They are not so strong, when you know this you know that when you will break them up, pi bonds will be the first ones destroyed. 

Because pi bond looks like the one above, the orbitals do not overlap so much, the force is not so strong. Second picture shows where is probability cloud strongest. The combination of sigma and pi bond is actually very efficient since it contracts the length of the bond making it stronger.

δ bond

δ is a delta bond. Actually I have never heard about this one before, but it is the bond that first appears when you have quadruple bond. This is very rare but some atoms can have even quintuple bonds between each other. When there is such a quadruple bond there is also one sigma bond and two pi bonds with delta bond. It creates by overlaping of two d orbitals, that is why it is called delta bond. Metals as rhenium, molybdenum or chromium can have such a bond.

On left you can see how this overlap should look like, this particular one is for two molybden atoms. But I can not really imagine how those look like really..

 

φ bond

φ is a phy bond. This last one is kind of only for fun since we were able to observe it only between two uranium atoms because they need two f orbitals which are found only in really heavy elements which are usually either radioactive or made only by human and usually both.

On the right you can see two f orbitals that could touch each other and maybe create this crazy bond.

 

So how is this related to covalent bonds and so on again? You can sort bonds between atoms into groups. For example bond between two carbon atoms will always be covalent bond because there is 0 difference in their electronegativity. It does not matter if there are two or three bonds inside. Then you can look on them and sort them if they are sigma, pi or even delta bonds which depends on their orbitals.

Dragallur