Atomic Bonding

Atomic Bonding

Quick note: for anyone who wants to actually read these and try to revise, i'll post 'em every Tuesday Thursday and Sunday night - and on some Saturdays, okay?

Okay, back to basics, again.

In GCSE Chemistry there are 3 main types of bonding:

• Covalent
• Ionic
• Metallic

For your exam in January, or whenever you're doing it (if you are) you should know these 3 types of bonding inside and out - at a GCSE level.

Lets start with the easiest...

Covalent Bonding

This type of bonding exists all around us, at the moment you're sitting in a room crowded with molecules 'using' covalent bonds so to speak.

A covalent bond is basically when atoms share electrons, like in the case of hydrogen gas, in which the formula is H2, Hydrogen is the lightest element with one electron on its outer shell, and the first shell (or energy level) can only hold two electrons, so hydrogen both share their electron with the other so they both have a full shell!

Here is a very helpful diagram I grabbed off Google to show you what they look like.

Covalent bonds can also be double bonded, where the atoms share 2 electrons each, or 2 groups of electrons.

This happens in oxygen, O2, where the oxygen both share two electrons, so in a sense, they both gain two! Thus filling their second energy level, or outer shell.

COVALENT ONLY HAPPENS BETWEEN TWO NON-METALS.

Ionic

Unlike covalent, ionic happens between a metal and a non metal. It is where atoms physically swap electrons, or give/lose them to gain a full outer shell, like throwing a baseball - got it?

Take table salt for that matter, also known as Sodium Chloride, or NaCl.

The first energy level on an atom can hold 2 electrons, and the second 8. Add these together and you get 10, 10 for two full outer shells. The third, for our purposes, can only hold 8 too, and this taking our grand total to 18 electrons, if it has anywhere near that many.

Sodium has 11 electrons, and Chlorine has 17, Sodium is one above 10, and Chlorine is one below 18.

Found the solution?
That's right, they 'swap' so to speak. And the sodium gives and electron to chlorine - and they are thus bonded by the charge difference due to that.

If you have 11 protons and electrons on a sodium atom, the atoms is neutral, right? 11-11=0.
However if you have 11 protons and 10 electrons on a sodium ion it is actually positively charged! 11-10=1 - however, sodium has its desired full outer shell, which all atoms want.

Quick note: for GCSE purposes, METALS ALWAYS BECOME POSITIVE. 1+, 2+ OR 3+.

Now lets look at chlorine, usually it has 17 protons and electrons, thus creating an equilibrium and a neutral charge.
An ion on the other hand has 17 protons and 18 electrons, 17-18=-1 and... a negative charge!
However, like sodium it has a full outer shell!

This is the basic theory behind ionic bonding, although they can be complex, but i'll go over that in the near future.

Metallic:

Possibly the easiest to understand but hardest to explain, but, here I go...

Metals will always have extra electrons on their outer shell, but usually no more than 3, but that doesn't matter right now - all you need to know is that metals lose electrons to gain full outer shells.

When metal atoms come together, i.e. Lithium  they give up these outer electrons and form a sea of given up electrons. This sea holds them all together.

Imagine a jam sandwich, the two slices of bread are the lines of lithium atoms, arranged in a neat form, and the jam holding the slices together is the sea of 'delocalized' electrons.

Litium has 3 electrons, if it gives up one, it has two and thus a full outer shell, so it donates an electron along with lots of other Li atoms, and forms a Li+ ion, and a delocalized electron. This sea of delocalized electrons generally holds the metal together, like the said jam. This is because the electrons are negative and the ions are positive, for our purposes.

The electrons in the metal are free to move around, this is why metals are the best conductors, as electricity is just a moving flow of electrons, a charge/coulomb.

Metallic bonding, like common sense should dictate, is strictly for metals.

Thanks, Ben.

Quick note: dissociated acids in water i.e. Sulphuric Acid H2SO4, will behave like an ionic substance in water although it is convalent due to the definition of a covanlent bond, and an acid etc. I will go over this soon.

Back To Basics

Back to the Basics.

Instead of complex things to do with physics, I thought i'd touch up on some chemistry, and try to help those revising for their January exam, like me for example. Reposting on this blog is purely for my own revision, but I thought i'd post it as my teacher says the best way to learn something is to go at it like you're teaching someone else it, so I thought I would actually try to teach others it.

The Basics.

Our old friend Mr. Atom - not Mr. Plum Pudding, Mr. Atom.

To start off, while doing chemistry - try not to mix Cu with CU - Cu is copper where as CU is carbon and uranium, and that's a pretty bad mistake to make. 

An atom is composed primarily of 3 things - a proton, a neutron and an electron but you should all know that. A proton has a relative mass of 1, a neutron of basically 1 and an electron of 1/1800 - so its a lot smaller, it barely has any mass at all. Protons and neutrons are made up of quarks, I wont speak about them, but I/we did do a "lesson" so to speak on them a while back, here. Protons and neutrons are found in the nucleus/nucleon and electrons are found 'orbiting' the nucleus or in an orbital. A proton is a positive particle and a neutron [like the word neutral] is neutral - REMEMBER, IT IS NOT NEGATIVE. Although it may have a dipole moment but that is not important. An electron is a negative particle. Since most atoms have an equal number of protons and electrons, they are neutral altogether - unless they are an ion... but i'll go over that soon.

Atoms are arranged neatly in order of groups and periods - a group represents how many atoms an element has on its outer shell and a period tells us how many shells it has. Group 0 is used because not all shells can contain 8, basically and this states that it has a full outer shell - in  basic terms.

Groups go down and periods go across. The first period contains helium, and it is in group 0. Group 0 means it has a full outer shell and is thus stable and does not need to gain any more electrons - and since it is in the first period, it only has one shell - and this is correct, helium has 2 electrons on its first energy level, and does not need any more electrons.

On the periodic table you generally have two numbers, one above the element and one below.

As shown by the diagram to the right, the number above is the "atomic number", or number of protons and the number below is the "atomic weight", or the "Relative Atomic Mass".

Not every periodic table is the same though, generally the smaller number is the atomic number, although it should specify on the actual table you are using. The atomic number (on a non-ionic element) will also be the number of electrons, as generally and atom has the same amount of protons and neutrons. So like said prior it has no net charge.

To work out the number of neutrons an atom has, simply subtract the atomic number from the weight/relative atomic mass to get said neutron number.

I.e. for Carbon: 12 - 6 = 6. So 6 neutrons.

I hope you learned something or at least jogged your memory a bit, thanks for reading.

- Ben.

String Theory

Due to recent mocking's about String Theory, I am going to do a post explaining the very basic concepts of string theory, with no math involved - although I may show the equation used to 'back-up' string theory.


String Theory basically says that all particles (ie gluons, electrons, tau's) are made up of vibrating string, that vibrate at many different 'pitches' if you want to say; these are "excitation modes."


There are two main types of String Theories, one with open string loops, and one with closed string loops. the strings with closed loops can break into open string (like snapping an elastic band in a sense) and those with closed string loops cannot break into open strings.


Like mentioned before in another post about SUSY (Super symmetry), SUSY is a big part in String Theory. When string theory contains fermions (basically elementary particles), SUSY is needed.


String Theory also tells us that there are more than our 3 general dimensions (left/right, up/down, forward/back) in some theories there are up to 14 dimensions!

There is not much to talk about while speaking about the basics of string theory, it is very complex and the math is very very hard to understand.


Here is just some of the math involved in String Theory, as you can tell - its not easy to understand.


String Theory is probably our best competitor for a T.O.E in my opinion, but it would take a lot to completely prove strings, the split apart a quark to find a string, we'd need a machine apparently as big as Jupiter!


String Theory is becoming more and more precise every day. It is the biggest and best theory of our universe.


Thanks for reading, Ben.

Methods of Terraforming

Methods of Terraforming

As I described in my last post the beginning of the terraforming process would need to include heating. A great rise in Mars' average temperature would be needed before a change was noticeable in an increase of the volume of carbon dioxide in the air. A mass increase in the average heat of the planet could be achieved through satelite mirrors which orbit Mars and direct a higher concentration of sunlight on to the planets surface - thus raising the temperature. Heating the frozen carbon dioxide on areas of the surface of Mars would achieve the desired affect of the increase of greenhouse gases in the environment. This is turn would heat the planet and this cycle would continue until optimum temperature was achieved.

I sometimes find it funny how on this planet we are desperate to decrease the number of greenhouse gases in the atmosphere however we need to increase them on Mars in order to achieve the first few steps of terraforming.

Another way that Mars could be heated is by producing power plants around the planet which have the sole purpose of making greenhouse gases. This in turn would cause the greenhouse effect which could start the 'cycle'.

After this process takes place and the heat of Mars is ok for human, animal or plant life - basic plants could be introduced to the surface able to survive some of the rest of mars' conditions. The plant life would photosynthesise and a little breathable oxygen would be introduced to Mars' environment. This would take years and would have to take place on a mass scale however the results would be amazing for the human race. Later on organisms like bacteria could be introduced and then more complex life.

Another problem that humans would have to tackle in order to make the planet habitable is Mars' lack of a magnetosphere. Since the planet does not have a magnetosphere harsh radiation would penetrate the atmosphere and harm any life living on the surface. So underground shelters or bunkers would have to be used to sustain life. 

The human race would have to make many sacrifices in order for Mars to become habitable however the end result would be magnificent - a new Earth for the human race.

Quantum Ghosts.

Quantum mechanics can describe many things, from the universe to gluons. M Theory and String Theory tell us there are 14/12 dimensions. What do these have in common though?


In quantum mechanics, particles can be in two places at once, or even everywhere at once. String theory tells us that particles can be in different dimensions.


And classical physics tells us that E.N.D. "Energy never dies."


So what happens when you die?


Where does the energy locked away in your body go?


It cant die with you, as energy cannot die.


Some people speculate ghosts to be particles in other dimensions, energy locked away in unknown dimensions, yet we can only see them at certain times. That is why we have 'sensed' ghosts, or even picked up heat signatures from them. Many people are sceptical about ghosts, they shun their existence and feel very strongly about this.


Why can't they exist, cause you can't see them? You can physically see air at room temperature, that still exists right? We have evidence toward ghosts, just since there is no physical explanation for them - we do not believe, and their existence being 'over-hyped' and 'over-exaggerated' in cinemas, movies etc.


Ghosts aren't too unrealistic, they're believable.


Exorcisms. Scary, yes I know - but real? That's for you to decide.


Many people have reported possessed people to spit up iron like fingers during an exorcism, and speaking in an unnaturally low, demonic voice - is it true? Can one's body really be possessed by a demon?


Watching footage of exorcisms is very very disturbing. Watch one if you may.


People would not go to the extent that they do in these videos of exorcisms if they weren't actually possessed. There are videos of women biting their own arm off (apparently), and it isn't CGI either. Could the devil exist in someone's soul? Many people says its all a lie. Many people would disagree.


It isn't their opinion that should matter to you, you should make your own assumptions. Its your life, right? You decide what you do... Unless you're possessed, then well - you cant. Ghosts can be anything, they could be energy manifesting itself into a human like form, or the particles in another dimension, in the shape of others. There is startling evidence toward the 'paranormal'.


What do you believe?


Thanks for reading, Ben.

The Photoelectric Effect.

In the spirit of Albert Einstein [again] i'm going to do a post on his, well what should be - most famous discovery. 

In 1905 Albert Einstein published a paper on the Photoelectric Effect [which I spoke about on Wednesday, it was in his 'Annus Mirabilis' year]. The photoelectric effect is the effect in which delocalised electrons are 'emitted' from a metal, due to the absorption of light.

Albert Einstein concluded that light is a particle, called a photon. Yet, it is also a wave. This is particle-wave duality, in light. 

These delocalised electrons can only be 'freed' if the wavelength of the light is high enough to over come to work function, i'm going to call the work function W [it is sometimes noted as Wo] - W is the amount of energy need to free an electron.

If we have red light, at a wave length of 700nm hitting sodium, will electrons be released?

In any equation you will be given W, which for sodium is 3.6x10^-19 J. 

You are given the wave length too, 700 nm, or 7x10^-7 m - you will also be told h, which is Planck's constant, or 6.626x10^-34.

If you didn't know, the energy of a photon is equal to E=hf or E=hc/λ.

So, E = (6.626x10^-34 * 3x10^8)/7x10^-7 - this equals... 

2.84x10^-19 J!

So, like Einstein found out, red light does not excite electrons enough to let them 'escape' the sodium, as it is not higher than W - or 3.6x10^-19 J.

Now onto violet light, with a wavelength of 400nm! Once again lets do our equation, but this time we'll use 4x10^-7m instead of 7.

So, E = (6.626x10^-34 * 3x10^8)/4x10^-7 - this equals... 

4.97x10^-19 J!

This is high enough to allow electrons to escape, and with a little extra math, we can work out their velocity too!

We'll use the equation: hf=W+1/2mv^2. Where hf is what we've just done, W is the work function, m is the mass of an electron and v is the velocity.

Since we know hf (we've just worked it out) as 4.97x10^-19 J, then...

4.97x10^-19 J = W+1/2mv^2.

Substitute an electrons mass and the work function of sodium into it and we get: 4.97x10^-19 J = (3.6x10^-19)+1/2(9.11x10^-31)*v^2.

You will always be given the mass of an electron, just incase theirs any confusion.

We can then work out the velocity by subtracting things from both sides.

Minus W off both sides and we get 1.37x10^-19 (4.97-3.6).

So, 1.37x10^-19 = 1/2(9.11x10^-31)*v^2.

If we times both sides by two, then divide by 9.11x10^-31 we get...

3x10^-11. The equation now states 3x10^-11 = v^2.

If we square root both sides we get the velocity, which is...

5.48x10^5 m/s - thats is incredibly fast!

Sorry for the long winded and mathematically challenging post, when you read this i'll be in Scotland somewhere so thank you for reading, once again;

Thanks for reading, Ben.

(If you're wondering why this is Ben's post since I said he was away this was saved in the drafts - as he said above he's in Scotland, thanks)

Terraforming

"All civilisations become either space faring or extinct."
-Carl Sagan

 Terraforming

Current projections show that the world's population will reach 9 billion by around 2050.

Our worlds population is currently growing at 1.15% per year.

In 40 years the population of Earth has doubled.
Doubled.

That's a growth of 3 billion per year.

We need more space - and fast.

The  more the population grows, the more food we need. The more energy we need. The more homes we need.

The more space we need.

Logically the human race needs to move and branch out from our home planet and soon. But since the space travel technology we have today isn't amazing perhaps we should looks for places closer to home, in our Solar System.

This is where terraforming comes in.

 

An artists conception of a terraformed Mars.

Humans can obviously not survive the temperatures of Mars (on average around −63 °C).
We can't survive the radiation on Mars' surface.

and without a great supply of water or a place to grow crops without an indoor maintained environment sources of nourishment would be bleak.

These problems restrict us as we need to wear space suits in order to survive for even a quick mission on planets like these.

And do you know how much these things cost?

A space suit today costs around 13-16 million dollars.

So some how I don't think a selection of the human race will be prancing around mars in these super priced suits.

We need to alter the environment of mars itself which will allow the human race to live how they are ... and their are certain ways to do this - as fantasy as it sounds.

The first step is that we would need to heat up Mars. 

The good thing about terraforming is that it is all a chain reaction - and technically it has happened before. On the planet we are on right now. Years ago our planet was riddled with lava and plate tectonics but now it is home to features like lush forests and fields. So this transformation can take place and maybe to induce it on other planets like Mars we should just look back to our distant past.

Heating up the planets temperature would start the process of a chain reaction by melting the supposed frozen carbon dioxide around Mars. Increasing the volume of carbon dioxide in the air is the basis of the 'plan'.

We all know that the basis of photosynthesis is that plants take in carbon dioxide and release oxygen right? So eventually by introducing plants or structures such as stromatolites onto the planet the planets environment could essentially become healthy enough to support human life.

Anyway, this is the basic idea of terraforming and I will be talking about it in more detail and describing some of the methods in future posts. I'm sorry for our strange blog schedule recently and we should get it back soon - (Ben is away at the moment and I will be taking over some of his posts.) But thank you for reading guys - Chris.