Here's a simple video before i the explanation. enjoy :)



This is very hard and difficult to understand explanation on oxidation from wikipedia (the link is at the end), if you can understand(i don't), then you're a genius! If not, read the simplified version of oxidation by scrolling down.

''Oxidation state is the measure of the degree of oxidation of an atom in a substance. It is defined as the charge an atom might be imagined to have when electrons are counted according to an agreed-upon set of rules: (1) the oxidation state of a free element (uncombined element) is zero; (2) for a simple (monoatomic) ion, the oxidation state is equal to the net charge on the ion; (3) hydrogen has an oxidation state of 1 and oxygen has an oxidation state of -2 when they are present in most compounds. (Exceptions to this are that hydrogen has an oxidation state of -1 in hydrides of active metals, e.g. LiH, and oxygen has an oxidation state of -1 in peroxides, e.g. H2O2; (4) the algebraic sum of oxidation states of all atoms in a neutral molecule must be zero, while in ions the algebraic sum of the oxidation states of the constituent atoms must be equal to the charge on the ion. For example, the oxidation states of sulfur in H2S, S8(elementary sulfur), SO2, SO3, and H2SO4 are, respectively: -2, 0, +4, +6 and +6. The higher the oxidation state of a given atom, the greater is its degree of oxidation; the lower the oxidation state, the greater is its degree of reduction.''

As taken from: http://en.wikipedia.org/wiki/Oxidation_state



In simple terms, oxidation is an increase in the oxidation number. Before we go on, oxidation is the interaction between oxygen molecules and the different kind of other substances there is they may contact, the substabces ranging from metal, plastics, living tissue.

Reduction is the decrease in oxidation numnber.An increase in oxidation number means that the oxidation number is getting more positive (+), therefore less minus. Oxidation is the loss of electrons, which are (-). A decrease in oxidation number means that the oxidation number is getting less plus, therefore more minus. Reduction is the gain of (-) electrons.

Therefore, higher oxidation number = positive (+) atom/molecule
lower oxidation number =negative (-) atom/molecule

Oxidation causes many things to happen, a common example being the rusting of metals:



Also, oxidation causes fruits to turn brown.
From that very moment when fruits are cut or bruised, the oxygen has free access to the plant tissue. In the presence of oxygen, polyphenol oxidase (PPO) enzymes in the chloroplasts rapidly oxidize phenolic chemicals naturally encountered in the fruit tissues to o-quinones. These chemicals interact with amino acids from proteins or they self-assemble to form brown polymers.



In conclusion, oxidation occurs when oygen reaches contact with enzynmes in the fruit and this causes chloroplasts to oxidize chemicals which are found in the fruit's tissues to form a substance which interacts woth amino acids or they self assemble to form browm polymers.

But this reaction is not the same in all fruits, since PPO activity and the amount of the phenolic chemicals can vary between different fruit varieties. PPO presence can also present variations linked to growing conditions and fruit maturity.

Browning can be impeded by either decreasing PPO oxidation activity or the quantity of phenols. Coating freshly cut apples in sugar or syrup can decrease oxygen diffusion, speeding down the reaction. Lemon or pineapple juices, rich in antioxidants, slow enzymatic browning when the apple is peeled. The acidity of these fruits also inhibits PPO activity.




However, the browning process is not always a bad thing. Wonder why tea, coffee and cocoa are brown? Indeed, browning is the cause of it all and browning which we know, is linked to oxidation.

Anyone fancy a drink?

When ms liang first explained to the class about the orbital theory, it was met with much confusement. However, in this post, i would try my best to help explain what is the orbital theory. I admit, after looking through various websites, i was bombarded by words such as wavelengths, pattern,etc. I have no idea what they mean. The explanations weren't exactly helpful. Still, this is what i came up with
.
ere's a video to kickstart this post:





Ok, so now we know what the s,d and p orbitals are.

Each orbital has a name. The orbital occupied by the hydrogen electron is called a 1s orbital. The "1" represents the fact that the orbital is in the energy level closest to the nucleus. The "s" tells you about the shape of the orbital. s orbitals are spherically symmetric around the nucleus - in each case, like a hollow ball made of rather chunky material with the nucleus at its centre.



The orbital above is a 2s orbital. This is similar to a 1s orbital except that the region where there is the greatest chance of finding the electron is further from the nucleus - this is an orbital at the second energy level.

If you look carefully, you will notice that there is another region of slightly higher electron density (where the dots are thicker) nearer the nucleus. ("Electron density" is another way of talking about how likely you are to find an electron at a particular place.)

2s (and 3s, 4s, etc) electrons spend some of their time closer to the nucleus than you might expect. The effect of this is to slightly reduce the energy of electrons in s orbitals. The nearer the nucleus the electrons get, the lower their energy.

3s, 4s (etc) orbitals get progressively further from the nucleus.

\ot all electrons inhabit s orbitals (in fact, very few electrons live in s orbitals). At the first energy level, the only orbital available to electrons is the 1s orbital, but at the second level, as well as a 2s orbital, there are also orbitals called 2p orbitals.

At the fourth level, as well the 4s and 4p and 4d orbitals there are an additional seven f orbitals - 16 orbitals in all. s, p, d and f orbitals are then available at all higher energy levels as well.




For the moment, you need to be aware that there are sets of five d orbitals at levels from the third level upwards, but you probably won't be expected to draw them or name them. Apart from a passing reference, you won't come across f orbitals at all.





Reference from this website

Radioactive isotopes and isotopes that. Here are but some examples:

1.Carbon 14 (the most common)

A radioactive isotope of carbon, it contains six protons, six electrons, and eight neutrons. Carbon 14 is produced when neutrons bombard atoms of nitrogen. •Carbon 14 is used in a common form of radioactive dating to determine the age of ancient objects used in date archaeological, geological, and hydrogeological samples.

There are three naturally occurring isotopes of carbon on Earth: 99% of the carbon is carbon-12, 1% is carbon-13, and carbon-14 occurs in trace amounts, e.g. making up as much as 1 part per trillion (0.0000000001%) of the carbon in the atmosphere.

Extra information:The half-life of carbon-14 is 5,730±40 years. It decays into nitrogen-14 through beta decay.The activity of the modern radiocarbon standard is about 14 disintegrations per minute (dpm) per gram carbon.

Here's a video of carbon 14 dating, it is done by forensic detectives so you get a sneak peek into a forensic's detectives lab. However, the website does not allow me to embed the video into blogger so with regrets, i give you the link so click here.

This is another vieo about carbon 14 dating but it does not have anything to do with forensics scientists. Instead, this video is talking about carbon 14 dating.:

Anyway, the reason why carbon dating is so important and popular becasue it helps determines the age of certain archeological artifacts of a biological origin up to about 50,000 years old. It is used in dating things such as bone, cloth, wood and plant fibers that were created in the relatively recent past by human activities. This has helped many archaelogist and historians create break throughs in science, benefiting mankind and increasind our knowledge about things that have happened in the past.

How Carbon-14 is Made (refer to picture for simplified version :D)
Co­smic rays enter the earth's atmosphere in large numbers every day. For example, every person is hit by about half a million cosmic rays every hour. It is not uncommon for a cosmic ray to collide with an atom in the atmosphere, creating a secondary cosmic ray in the form of an energetic neutron, and for these energetic neutrons to collide with nitrogen atoms.

When the neutron collides, a nitrogen-14 (seven protons, seven neutrons) atom turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons). Carbon-14 is radioactive, with a half-life of about 5,700 years.
­The carbon-14 atoms that cosmic rays create combine with oxygen to form carbon dioxide, which plants absorb naturally and incorporate into plant fibers by photosynthesis. Animals and people eat plants and take in carbon-14 as well. The ratio of normal carbon (carbon-12) to carbon-14 in the air and in all living things at any given time is nearly constant.

Maybe one in a trillion carbon atoms are carbon-14. The carbon-14 atoms are always decaying, but they are being replaced by new carbon-14 atoms at a constant rate. At this moment, your body has a certain percentage of carbon-14 atoms in it, and all living plants and animals have the same percentage.

2.Hydrogen

Normal hydrogen, or hydrogen-1, has one proton and no neutrons (because there is only one proton in the nucleus, there is no need for the binding effects of neutrons). There is another isotope, hydrogen-2 (also known as deuterium), that has one proton and one neutron. Deuterium is very rare in nature (making up about 0.015 percent of all hydrogen), and although it acts like hydrogen-1 (for example, you can make water out of it) it turns out it is different enough from hydrogen-1 in that it is toxic in high concentrations.
The deuterium isotope of hydrogen is stable. A third isotope, hydrogen-3 (also known as tritium), has one proton and two neutrons. It turns out this isotope is unstable. That is, if you have a container full of tritium and come back in a million years, you will find that it has all turned into helium-3 (two protons, one neutron), which is stable. The process by which it turns into helium is called radioactive decay.

Now, lets talk about deuterium.

Deuterium has primarily two uses, as a tracer in research and in thermonuclear fusion reactions.

A tracer is any atom or group of atoms whose participation in a physical, chemical, or biological reaction can be easily observed. Radioactive isotopes are perhaps the most familiar kind of tracer. They can be tracked in various types of changes because of the radiation they emit.

For more than four decades, scientists have been trying to develop a method for bringing under control the awesome fusion power of a hydrogen bomb for use in commercial power plants. One of the most promising approaches appears to be a process in which two deuterons are fused to make a proton and a triton (the nucleus of a hydrogen-3 isotope). The triton and another deuteron then fuse to produce a helium nucleus, with the release of very large amounts of energy. So far, the technical details for making this process a commercially viable source of energy have not been completely worked out.



In nuclear physics and nuclear chemistry, nuclear fusion is the process by which multiple atomic nuclei join together to form a single heavier nucleus. It is accompanied by the release or absorption of large quantities of energy. Large scale fusion processes, involving many atoms fusing at once, must occur in matter which is at very high densities.

Some suggested advantages of commercial fusion reactors as power producers are:

-An effectively inexhaustible supply of fuel—at essentially zero cost on an energy production scale;
-A fuel supply that is available from the oceans to all countries and therefore cannot be interrupted by other nations;
-No possibility of nuclear runaway;
-No chemical combustion products as effluents;
-No afterheat cooling problem in case of an accidental loss of coolant;
-No use of weapons grade nuclear materials; thus no possibility of diversion for purposes of blackmail or sabotage;
-Low amount of radioactive by-products with significantly shorter half-life relative to fission reactors

A thought-provoking and intriguing video about our future with nuclear fusion: