2009 4 August Chemistry Chemical Changes Post FIVE Okay, this is the FINAL AND OFFICIAL POST!
I shall start with Covalent Bonding. Firstly, I will be showing you two self-drawn pictures.   In the first picture, we can see that the hydrogen atoms only have one electron, and the valence electron value for hydrogen is 2. However, we see two hydrogen, and each of them are trying to attract the other hydrogen's electron. However, if one does attract it, one hydrogen would have no electron (impossible), hence, they share a covalent bond, and inside that covalent bond, there are 2 shared electrons, 1 for each hydrogen, hence, each hydrogen would have 2 electrons. Sometimes, there are multiple bonds.   Instead of sharing a bond to complete the valence electron of 6, there share multiple bonds. The diagrams I have used above is called the Lewis Dot Structure. Here, I have come to the end of my BioChem Journal, here is the reflection for the Chemistry Journal. During the course of my research, I believe that everything that I have come across is interesting. During the course of the research, I have learnt a lot of new things, and many things surprise me. Also, not only did the information that I have gained surprised me a lot, I have also learnt a lot of new stuff. All of these information surprises me as before I carried on with this research, I did not know that things work that way. Of course, after the research, there are still many things left unanswered. The world is so big and there are so many scientific knowledge. Some queries would be examples of chemical reaction, for example, mixing chlorine and sodium, what causes the spark and how do people produce table salt in mass quantities. Also, I would also be interested to find out how chemical reactions can help the world evolve, or how has it already helped the world to evolve at the current stage it is now. This time, the difficulties faced are much greater than the ones faced when doing the Biology Blog, this is so as during the course of the research, the common mastery reviews are also nearing by, and national day parade is also coming, hence, there is less time for us to do our research and in turn, do our blog posts. Hence, we have to learn to manage our time wisely, also, the topics given were hard as we have not started learning them yet, so we had to pre-learn some things before it was taught in class, if not, there would not be enough time. My personal response would be that I was really shocked and I learnt a lot of things about Chemical Changes, Chemical Reactions and of course, bonding. I have also learnt applications of Chemical Reactions, and elements, most importantly, like how carbon is compressed under high pressure to make diamond, how copper is bent to make wires, how graphite is used as the lead of our pencil cases, how silver is malleable and ductile and bent to made jewelery which we wear today, etc. And yes, it has influence me, I have started to look at the world in a different perspective. Sometimes, I wonder how is everything made, how is our computer made, and I have become more curious. I also want to find out more about this topic, and hope that my research continues. Also, this has also urged me, if I have the chance next time, to go explore factories and observe the different processes in the factories, what type of chemical reactions they use, what elements do they mix in order to form everyday materials that we find. Also, after the course of this research, it has urged me to regularly check the periodic table for any new elements discovered, and keep up to date with any changes in the atomic number, or the positioning of the elements. Lastly, I hope that I can still continue posting on my BioChem Journal Blog. There will still be 2 more posts, Fun and Interesting Facts on both the Nutrient Cycle and Chemical Changes, so do check back often. Also, I hope to continue the blog, and I will be posting about interesting scientific stuff I have seen in my life. So, bye! Link One Glossary Electrons Positively-charged atoms 2009 2 August Chemistry Chemical Changes Post FOUR
Hey guys! Made some changes to the skeleton, and I can confirm that this will be the final skeleton I'm following. I added in an Introduction to Elements, as I thought it would be important for you guys to understand more about elements before we continue on. Also, I removed Metallic Bonding, although my topic is on Chemical Changes, I did not want to dwell too much on bonding, hence, I removed part of it. Without further ado, I shall begin. C6H12O6 This is the chemical symbol for glucose, or sugar in this case. As we can see, it is made up of C (carbon), H (hydrogen) and O (oxygen). Imagine if all these were separated, what would you get? You would get something that cannot be broken down into simpler substance by chemical reaction, and THAT, is an element. Hence, element is defined as a substance which cannot be broken down into simpler substances by chemical reactions. Hence, it is the building block of matter. Another example would be water during electrolysis. It breaks down down into Hydrogen and Oxygen. Hence, Hydrogen and Oxygen are elements. We use Chemical Symbols to represent some elements. Most of the elements come from the first letter, for example, Hydrogen's Chemical Symbol is H. Some comes from the first two letters of the Chemical. However, every letter that follows the first letter must be in small letter. For example Aluminium is written as Al. Sometimes, not the first two letters are used, Chlorine is written as Cl for example. Others come from other language like latin, example would be Tungsten, which is written as W. Elements can be classified into two different types. Metals and non-metals, we will talk more about that later. Some examples of metals would be mercury, tin or aluminium. While non-metals would consist of chlorine, bromine, sulphur or iodine. Metals are normally shiny and have high density, they also have hgih melting and boiling points. It can conduct electricty and heat well, and is normally ductile and malleable. There are many different uses of elements, for example, carbon can be compressed under high pressure to form diamonds. Nitrogen can be formed into liquid form to keep things cool. Mercury can be fit inside a thermometer to measure temperature. Or carbon can be made into graphite which is what we use in pencil lead. With this, I will move on to ionic bonding. As I have said earlier, sodium metal combines with chlorine gas to form table salt. In this bonding, sodium loses one electron to the chlorine gas, and chlorine will complete its valence electrons and it will become 8 electrons.   And that is basically ionic bonding. Also note that after the bonding, the sodium turns into a negative-charged ion andd the chlorine gas turns into a positive-charged ions. With that, I end this post. In the final post, I will talking more about Covalent Bonding. Link One Glossary Electrolysis Using electricity to drive a chemical reaction. Ductile Able to be easily bent. Mallaeble Can beaten into shapes. 2009 1 August Chemistry Chemical Changes Post THREE
Alright! Good! We're coming to the last two section of the Five Major Chemical Reaction! So let's not delay! Also called Single Displacement, Single Subsitution or Activity Replacement. Single Replacement, as the name suggests, is basically one component of a compound "going" to the other. For example, if we place a piece of copper into a silver nitrate solution, slowly, you would see that the copper begins to turn into a silvery-white material, and the solution begins to turn from light silver into blue. What is actually happening is that the silver from the silver nitrate solution is "going" to the copper, hence, we can represent Single Replacement with a simple equation. AB and C -> A and CB Or in the previous case, the copper and silver nitrate solution can be represented like this. 2 AgNO3 + Cu -> Cu(NO3)2 + 2 Ag There are two types of Single Replacement, mainly cationic and anionic Single Replacements. In an cationic Single Replacement, ions are produced, while in an anionic Single Replacement, ions are not produced. The above reaction would be considered cationic as it is likely to make cations. An example of anionic reaction would be bubbling chlorine gas in a potassium iodine solution, the chlorine is used up and the solution turns purple-brown because of the iodine. Also represented as, 2 KI + Cl2 -> 2 KCl + I2 Now that we have finished Single Displacement, I will move on to Double Displacement. As we have said just now, Single Displacement is the component of a compound "going" to another compound or element, in Double Displacement (also called Double Replacement or Metathesis), instead of "going" to the other compound or element, it switches place with another component of the other compound. One common example would be hydrochloric acid (acid) and sodium hydroxide (base) would neutralize each other (as one is acidic and one is alkaline) to make water and salt. This can be written in this way. HCl + NaOH -> HOH + NaCl Hence, we can simply write Double Displacement as... AB and CD -> AD and CB Now that we have finished all five major chemical reactions, you might be wondering, how can some of this happen? One major thing would be bonding. And that is what we are moving on to next. Have you ever wondered even though the Periodic Table only has 118 elements, why are there so many we see in our everyday life? This is so as the elements can bond together to make other elements. So in this case, why do bonding happen? And how does bonding occurs? It is said that atoms with less than 8 valence electrons will bond together with other atoms to "complete" the full 8 valence electrons. In the periodic table, different groups of metal are classified according to their different valence electrons. Group One has 1 Valence Electron. Group Two has 2 Valence Electron. Groups Three to Twelve have Electrons that are normally not easy to count with the orginial way. Group Thirteen has 3 Valence Electons. Group Fourteen has 4. Group Fiveteen has 5. Group Sixteen has 6. Group Seventeen has 7. Group Eighteen has 8 or 2. (in the case of Helium, it is 2) An simple bond would be between sodium and chlorine gas, which would result in the table salt of what we have now. So how is bonding done? Well, it is exactly the same as magnets. The negatively charged electrons would attract the positively charged protons, and it completes the bond this way. A amount of energy or heat is needed to separate these bonds. Now that I have come to the end of the introduction to Bonding, we will be talking more about elements, and of course, the two different types of bonding I am going to touch on would be Ionic Bonding and Covalent Bonding. Link One Link Two Link Three Glossary Cation A positively-charged ion. Valence Electron The number of electrons on the outmost shell of a certain element. 2009 30 July Chemistry Chemical Changes Post TWO Sorry to say, this post will be EXTREMELY SHORT! >.< I'm really sorry. For the next two post, will be just a brief demostration on the different chemical reactions.
Okay, let's start. What can we understand from the term Synthesis? No, it is not photosynthesis! It is Synthesis! Well, Synthesis is actually a form of reaction, whereby an element combines with another element to form a compound, or in other cases, an element and another compound combine to make a new compound. Or sometimes, two compounds combine together to create a new compound. Synthesis is also called combination, construction or composition reactions. Remember this, we can represent Synthesis with this simple equation. A + B -> AB A very common example would be burning hydrogen gas and oxygen gas to produce water, which also can be represented by the equation. 2 H2 + O2 -> 2 H2O Or, another example would be that sulfur trioxide reacts with water to make sulfuric acid. Or in this case, is... H2O + SO3 -> H2SO4 So what you would see in a 'test tube' would be that two substance combine to make one new substance. And that sums up Synthesis. Decomposition, in order words, is also called, desynthesis, decombination or deconstruction. As we can very obviously see from the word Desynthesis, we can actually that it opposite of Synthesis, hence, it is the separation of a compound into other elements and/or compounds. We can simply repesent it in this form. XZ -> X + Z Now, we will look at some examples of decomposition. If we heat a bicarbonate soda of water, it will release water, carbon and sodium carbonate. We can represent it with this equation. 6 NaHCO3 -> 3 Na2CO3 + 3 H2O + 3 CO2 Next, and lastly, I'll move on to combustion. Combustion, as the name suggest, is basically the burning of organic material. In order for combustion to happen, there must be oxygen, this is so as the material will react with the oxygen in the air around it to burn. We can simplify combustion, and write it in this form. Hydrocarbon + Oxygen -> Carbon Dioxide and Water To further demostrate combustion, if one candle if left out in the open to burn and the other is covered with a beaker, the one left out to burn will obviously burn longer than the one in the beaker as in the beaker, there is limited amount of oxygen for the 'fire to eat'. Here are some examples of combustion. CH4 + 2 O2 -> 2 H2O + CO2 The next one... 2 C2H6 + 7 O2 -> 6 H20 + 4 CO2 And with this, I have come to the end of this Chem Journal post. Link One Link Two Link Three Glossary Element Anyone of the substance in the periodic table. Compound A substance formed by a union of two or more elements or compound with a definite propotion by weight. Organic A class of chemical compound having a carbon basis. Hydrocarbon A organic compound that only contains hydrogen and carbon. 2009 29 July Chemistry Chemical Changes Post ONE Hey! Long time no see! Okay, because of the deadline and me being down with flu this few days, bear with me, I might have to post two to three post in a day. Alright, I thought this year the Chemistry topics were hard to choose from. Now, let's start. Here's the rough skeleton I will be following, and it is not confirmed yet, will tell you guys when its confirmed.
I am sad, and sorry to say, that this time, each post would not be very long, in fact, it would be quite short. About two to three paragraphs. Now, I will begin. Again, before we start, here's a nice and short clip for all of you to enjoy and will sure help you understand more about Physical and Chemical Changes. Do take some time to watch it. As you might have seen from the video already, there are differences between Physical and Chemical Changes. A physical change is whereby a matter or substance changes physically, meaning that it can change its state it is in (solid, liquid, gas, plasma) or it can change its size or shape, however, the substance that makes up the object, does not change. For example, you can take a piece of paper and cut it up into small squares, it will still remain as paper. Hence, that is physical change. Or, you can take a cube of ice and melt it, just because water changes from a solid form to a liquid form, it doesn't mean its a Chemical Change, because nothing in the substance is changed, as water still remains as water, except in a different form. Hence, that, is also Physical Change. One important thing about Physical Change is that it can be reversed. After melting ice to become water, you can then cool it to make it into an ice cube again! However, Chemical Changes are different. Firstly, a Chemical Change is where there is a Chemical Reaction. The substances in the matter is changed during Chemical Change. Chemical Change can form a new substance, and most importantly, during Chemical Change, energy is either given off or absorbed. If you would to take a piece of paper and burn it, it would be Chemical Change, as a new type of substance is produced, and of course, Chemical Changes cannot be reversed, even if it could, it would take extraordinary means to do it. For example, if you fry an egg, it would be very hard, or even impossible to "un-fry" it. During Chemical Changes, heat is either lost or gained. If heat is lost, we call it an exothermic reaction. If heat is gained, we call it an endothermic reaction. The temperature pressure and substance involved in the change (or reaction) will affect the speed which at the change (or reaction) takes place. Previously, I did mention that Chemical Changes is where there is a Chemical Reaction, so, I will be zooming on to the topic of Chemical Reaction now. Again, I would like you all to watch a few videos about Chemical Reactions. So what exactly is happening in the videos above? Well, Chemical Reaction! However, in Chemical Reactions, there are five major types of Chemical Reactions, namely Synthesis, Decomposition, Single Displacement, Double Displacement and finally we have Combustion. And I will talk more about these in the next few posts. With this, I will end this post. Link One Link Two Glossary Physical The outer surface of something, normally able to be able to observe. Substance Something which has mass and occupies space. Exothermic A compound formed with the liberation of heat. Endothermic A compound formed with a absorbtion of heat. 2009 14 July Biology Ecology and Nutrient Cycle of the Ecosystem Post FIVE Haha, hey guys. This WILL BE MY final and official post. =) I decided to merge the conclusion post with this post, and my last post about the Fun and Interesting Facts would NOT BE AN official post. Also, I decided to remove the Nutrient Cycle part, as I thought it was irrelevant.
And lastly, starting my final post. ;D Many people have a misconception that the transfer of energy starts with plants, however, that is wrong. It actually starts with the Sun. The Sun is the primary source of energy production, the plants need it to photosynthesize, and hence, creating food. The first and foremost step that energy is produced, would happen within the primary producers, or as we more commonly know it as, plants. Next, the herbivores, or primary consumers, would consume the plants, and hence, the energy that the primary producer has created is transferred to the herbivore. Next, carnivores eat herbivores, or other carnivores, and from there, the energy in the herbivore is transferred to the carnivore (secondary consumers, tertiary consumers and quaternary consumers). Lastly, the detritivores, as I have mentioned before, consume the carcasses of dead animals and also consume our droppings. Before I continue, here's a simple figure.  The diagram above basically summarizes what I have said. However, notice that the diagram flows of trophic level to trophic level, and at all levels, waste is produced. Also, as the trophic level descends, the energy that is being passed on to the next consumer is decreased gradually. For example, the primary producers would have 100% energy, while the primary consumers would only get 95% and the secondary consumers would get only 85%. Also, what I have shown above, can be considered a skeleton for a food chain, and that is what I am going to go on to next. As I mentioned above, food chains basically show how each consumer gets their food. However, you might ask, what is the diference between a food chain and a food web? A food web is basically a larger scale of the food chain, it is actually two or more interconnected food chains. Do you know that in a food chain, the amount of herbivores are more than the amount of carnivores? That happens because as I have mentioned earlier, when a consumer eats, not all of the energy is passed to it. Hence, to make sure that it balances, there has to be more herbivores for the carnivores to feed on, and of course, more primary producers. Normally, there are mainly most primary producers, followed by herbivores, followed by carnivores, forming a pyramid shape. As you can see below.  Next, would be food webs, as I promised in Post Three, I would put up the different food webs of the ecosystems that I have mentioned.    Above are the Marine, Aquatic and Desert Food Chains and/or Webs respectively. Lastly, there is one important point to note about food chains and food webs, is that the population change of one group can cause the population change in others. One example would be that if the herbivores start to increase, there would be less primary producers, as there are more herbivores to eat them. When there are less primary producers than herbivores, it means that the herbivores would not have enough food to eat, and will start dying. This would cause the carnivores to not get eonugh food too, and start decreasing. However, when the carnivores start decreasing, the herbivores increases, and the cycle continues. That is why it is important to make sure that in a food chain/web, the structure is kept as an pyramid shape. This also shows that the organisms in the food web are interdependent! With that, I end my Biology Journal! During the course of this journal, it made me learn a lot of things. Here's the reflection, it will be on the report too. Of course, during the course of my research, there is no such thing as what is the ‘most’ surprising/interesting information I came across. The topic I chose, Ecology and the Food Cycle in the Ecosystem, was totally unfamiliar to me. Hence, everything that I had found out, had either amazed me, or I have learnt something from it. However, there was a few things that amazed me greatly, one would be the big word which I found out on the course of my research, biogeochemistry. It is a form of science, and people who study it are called biogeochemist. I was surprised that biogeochemists actually had a way to find out which organism is more important than the other, by ways like nutrient cycling or mass balance. Secondly, it would have to be the vast amount of ecosystems that I came across. Before the course of my research, I only thought that there were a few ecosystems, and hardly even knew what ecosystem meant. Of course, after this research, there are still a lot of things that I would like to find out more about ecosystems, I would really like to go to places like the desert, and actually have a look at the ecosystems there, and compare it with other ecosystems. From that, I meant that I would like to know the differences and similarities of the different ecosystems. Also, I would like to find out more about the human ecosystem. This is so as in many ecosystems, there are carnivores and herbivores. However, I believe that in the human ecosystem, carnivores and herbivores do not exists, although we eat meat and vegetables, I believe that that only constitutes a small part of our ecosystem. Of course, difficulties faced during research are inevitable. One of the major difficulties that I faced was finding for information. Many websites I went to only gave a brief view about ecosystems, the different types of ecosystem, and many times, they were written in very sophisticated terms, so I had to search the dictionaries and find out the meaning of some words, before I can fully understand the text, so that I can rephrase it. I thought that I did not take the wrong path of researching on ecosystems, it taught me a lot of things that I didn’t know, and I believe, many of us did not know too. Of course, I learnt a great lesson, and that would be to save the Earth. Through the course of the research, I have found out, how Earth was like before, and now, and will be. Our ecosystems are slowly dying one by one, and as ecosystems die, not only will the beautiful scenes of nature be gone, but also the animals and plants in it. This is all causing habitat degradation or fragmentation, and slowly, the Earth will fall apart piece by piece. I think that we ought to spare a thought for our future generations, it would be unfair for them if we get to see Earth, in its beautiful state, and for them, destroyed in ruins. With that, I end my reflection. 520 words After this research, I hope that it has urged you to find out more about our Earth, and help to conserve it! Just to remind you guys, Post Six (Fun and Interesting Facts) will not be an official post. The official Biology Journal ends here. Looking foward to Chemistry Journal! ;D Link One Link Two Link Three Link Four Link Five Glossary Trophic Level A group of organisms that make living in the same way. Gradually Slowly Interconnected Linked to each other in a certain way/manner. Interdependent Needs one another to function properly 2009 13 July Biology Ecology and Nutrient Cycle of the Ecosystem Post FOUR Hi! ;D This post's going to be quite long, yup. Biogeochemistry's a big topic to talk about. Haha!
Alright, no more delay, let's just start. As we all can see, the big word, Biogeochemistry, involves and is made up of mainly three words, biology, geology, and chemistry. So, we can roughly infer, that biogeochemistry is the study of biology, geology and chemistry. More specifically, it is the study living systems, us, and other living animals, are affected, influenced and controlled by the geology and chemistry around us. Hence, it includes the study of many biotic and abiotic world around us. One important use of biogeochemistry, would be to anazlyse, in the food web, which of the linkages are more important than the others. One obvious way would be to study the cycling of elements, like how each organism are controlling or changing the elements. Biogeochesmists do this in 3 major ways, and they are also the principle and tools of biogeochemistry. They are mainly element ratios, mass balance and element cycling. Alright, I will start with element ratios. Here's a quote from the site. In biological systems, we refer to important elements as "conservative". These elements are often nutrients. By "conservative" we mean that an organism can change only slightly the amount of these elements in their tissues if they are to remain in good health. It is easiest to think of these conservative elements in relation to other important elements in the organism. For example, in healthy algae the elements C, N, P, and Fe have the following ratio, called the Redfield ratio after the oceanographer who discovered it: Let me break down, what this paragraph is talking about. As stated above, important elements (nutrients) are called "conservative". So, as we know, they are not only important to the organisms around us, but also us. Hence, if an organism would to use or convert less conservatives in order for it to stay in its healthy condition, it would be more important for us, as they take up less conservatives. Next, I will talk about mass balance. Here is the quote from the site. Another important tool that biogeochemists use is a simple mass balance equation to describe the state of a system. The system could be a snake, a tree, a lake, or the entire globe. Using a mass balance approach we can determine whether the system is changing and how fast it is changing. The equation is: In this equation the net change in the system from one time period to another is determined by what the inputs are, what the outputs are, and what the internal change in the system was. The example given in class is of the acidification of a lake, considering the inputs and outputs and internal change of acid in the lake. Basically, this method is to find out what is the change of a certain system, and the rate of it changing. Net change basically means the original change of a certain system, without other factors disturbing it. The example above given was a lake, hence, the input could be what humans are doing to the lake such that it is becoming more acidic. The output could be what humans are doing to help the lake, such that its acidity level decreases. Lastly, the internal change would what is happening inside the lake, that causes its acidity level to increase or decrease, or fluctuate. Lastly, element cycling. It is basically to find out how fast nutrients or elements are moving in a system, and as I have explained before, there are two types of system, an open system, and a closed system. A recap, a closed system is where inputs and outputs are minor compared to the internal change. An open system is when inputs and outputs play a major role together with the internal change. To measure the element cycling in a closed system, we take a look at two things. The rate at which is going, which is basically the amount of cycles divided by the time needed to make all the cycles. Secondly, we can at the pathways where the elements are going, this is important as different pathways can cause different chemical reactions to the elements. To measure the element cycling in a open system, we use both rate and pathways, with a new factor included, with is the residence time. As in an open system, the inputs and outputs are considered, residence time would measure how long a element is staying inside a particular system. So with these three principles and tools, we can measure and determine which organism in the food web is more important. (I will be talking more about the Food Web in my next post) With that, I end my post. Link One Glossary Biology The science that involves studying living organisms. Geology The science that involves the history of the Earth. Chemistry The science that involves studying the propeties of organisms. Acidification The process whereby something becomes more acidic. Principle A common rule or standard is accepted and used. |
By Zhan Peng from 2-6 Catholic High School Class 2-6 One Golden Rule NOTHING |
