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Chemistry and scientific hobby equipment
Welcome to this online presentation of hobby chemistry kits and science kits. Pleace click on a banner or link to learn more or to buy. The kits presented here are only examples. By clicking at any product link, you get into online stores with a lot more science hobby products and other hobby products than those presented at this page. At the nottom of this page there is some general information about chemistry and physics.
Good stores for hoby science items
Science kits - physics, technology, biology, astronomy, metaorology
Other hobby items
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Trendtime Toys - science kits, RC models and other hobby items - This is a general hobby
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Weather forecast equipment - Wheather forecast units that contain equipment like thermometers, barometers, chronograph clocks, rain sensors, humidity sensors, wind measurers and computing electronics to calculate forecasts and show the results.
Orion astronomy equipment - Equipments to look at and take pictures of celestial objects and whole celestial sceneries.
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Good sources of RC model and other hobby itemsXenonproject.com - A well categorized store for RC models - This is a coprehensive online store for all types of radio controled models, RC airplanes, RC cars and trucks of all kind, RC boats and RC helicopters. The models are well organized in cathegories so that you easily find that type of model suited best for your purposes or for the person you buy a moel fo as a gift.
What is chemistry?
About chemical bonds and structures
Our world is made from atoms. Atoms consist of a kernel consisting again of positively charged protons and uncharged neutrons, and a cloud of surrounding negatively charged electrons moving about the kernel. Positive and negative charges attract each other, and therefore an atom is hold together.
However, it is possible for electrons to be situated in such a way between atoms that they attract the kernal of two or more atoms. Such electrons will attract the atoms together.
Some atoms attract by themselves electrons, so that the atom gets negatively charged. Other atoms by themselves pull electrons away, and get positively charged. A negatively and a positively charged atom will attract each other.
These two attractment effects, alone or blended together, can effectively bind two or more atoms together, or making a chemical bond. Usually a bond consists of two electrons making an attraction effect.
Units of atoms bound together are often just small and equally composed. If so the units of atoms bonded together are called molecules. In other cases they can be larger, but still equally sized and composed. These will also usually be called molecules.
In other cases, the units are composed of atoms arranged in a regular fashion, but can be of any size, and are most often very great with billions of atoms in each unit. Techically such units are giant molecules, but they are usually called crystals, or corns or something similar. A diamant is a typical example of such giant molecule or crystal. Metals are also composed of such crystals, and these are usually called corns if small and crystals if great.
Even though a compound consist of small equally sized molecules, these mulecules can glue together in a regular fashion and make objects with a regular shape. Such objects are also called crystals. An example is a sugar crystal.
And crystals can glue themselves together to even greater objects, like for example stons in rocks.
There are several kinds of bonds:
Covalent bonds: In such a bond, the shared electrons are equally distributed between the atoms.
Polar covalent bonds: By these bonds, one atom attract electrons by itself to some degree and another repels electrons by itself to some degree. The atoms then get some degree of opposite charges and will attract each other by an ectrostatic forc. Electrons will also to some degree situate themselves between the two kernels and attract both the two atom kernels, and also this way bond the atoms together.
Ion bonds: Here on of the atoms repell some electrons totally by itself, and the other attracts the same electrons totally. The electrons will not be shared, but the positively sharged atom and the negatively charched atom will attract each other.
Metallic bonds: Here electrons are free to move around many atoms in a crystal, and will often be situated between the kernels. They thus hold the atoms together, and because they can move around, they can lead electric current.
Hydrogenbonds: A hydrogen atom usually produce polar covalent bonds with the hydrogen becomming positive. A hydrogen atom in a chemical structure is therefore attracted to atoms in other structures that are positive after forming a polar covalent or ion bond. This attraction aan be so graet that the two structures are glued together. This type of nond is called a hydrogen bond. Basically also other pairs of positive and negative atoms can make such bonds, but they are especuially common with hydrogen. The atoms that attract hydrogen this way is often oxygen.
Physical states or aggregate states of substances
The chemicals that react during a chemical process and the result of the process can be in several physical conditions, or aggregate conditions, of which the main types are solids compounds, liquids or gasses
Solid compounds: In a solid compound, the forces between the molecules or atoms are so strong that the molecules are held together in one piece, and the molecules or atoms are locked against each other so that a piece keeps its form even though it is influenced by external forces, as long as the force does not exceed a certain size characteristic of the compound.
Solid compounds - chrystalline: If the binding forces in a solid compound lock the molecules or the atoms toogether in a regular fashion, the comound is called chrystalline.
Liquids: In a liquid the forces between the molecules are great enough to keep the molecules of a substance to escape away from each other, but the forces do not lock the molecules rigidly against each other, so the molecules can easily slide between each other. Therefore a liquid does not keep a permanent shape and will float out on a surface because of the gravitation.
Gasses: In a gas there are not enough forces between the molecules to hold them together. Any pressure or external force will keep a piece of gas to inflate and go apart in all directions. Therefore a gas must be held in a locked container or something acting like a container. The air is a gas, and this gas is held in place around the earth by gravity.
Plasmas: A plasma is a gas where electrons are broken out from the atoms or molecules and hover between the atoms or molecules. The molecules or atoms are then positively charged because they have more protons in the kernels than electrons in the shells around the kernel. Plasmas are most often produced by very high temperatures. Because the negative electrons tend to attract the positive constituents, a plasma is often held together as one piece, even though the constituents can move freely around in the plasma and the plasma do not have any specific shape.
This simple theory of matter conditions is an over-simplified picture. Many things in nature and daily life behave in a way that is different from this description. For example a thread or a piece of fabric that behave nearly as a liquid upon forces in some directions and as a very solid thing upon forces in other directions so that a piece allways is held together and so that the topography of the piece allways is intact. The topography of an object describes what parts of an objects that are fastened to each other.
Anoter example of a thing that neither is a liquid nor a solid in the strict sense is a robber band. It can be stretched until a certain limit, but at that limit it behaves very much like a solid object, and the topography of the rubber band is allways intact, but apart form this, the rubber band does not have a permanent form.
About chemical reactions
During a chemical reaction chemical bonds are broken, and then new bonds are formed between the broken pieces of the original molecules. But usually new bonds are formed between other pieces than those hold together originally. Thus new compounds are formed.
In order to brake bonds, energy must be supplied. The atoms or molecular pieces bound together have usually less energy than the atoms not bound. Therefore a chemical structure can only be splitted with the supply of energy. The energy gives power to overwhelm the attractive forses in the bonds. The energy can be supplied by heat, by light or by electricity, dependent upon the type of reaction. It can sometimes also be directly supplied from other molecules that undergo a simultaneous reaction.
Then new bonds are formed by the free atoms or free molefcular pieces, so that elements broken free are again combined to new molecules or other structures. In that process energy is released in form of heat, in form of emited light, as electric current or the released energy is transfered directly to other molecules.
In the over-all process the release of energy druing formation of new bonds can be greater that the energy needed to break the original bonds. If the released energy is greater than the energy supplied to break the original bonds, the reaction produces net enery. Such a reaction will produce heat, light or an electric current. Such reactions will often proceed by themselves when it has begun because released energy can be used to break new bonds. Such a reaction is called exoterm. If an exotherm reaction is strong enough, it will produce glowing materials because of the heat, for example glowing gasses. Such a result of a reaction is commonly callled fire.
Other reactions need more energy to break the original bonds that the energy released when new bonds are formed. Such a reaction must allways have a continuous supply of energy to proceed. Such reactions are called endoterm reactions.
During a chemical reaction, the reacting the substance can change aggregate state in a lot of ways. Solids liquids or gasses can produce both solids, liquids and gasses as a product, or something that cannot be described as neither of these.
When a reaction occur so that products are formed, the opposite reaction will olso occur. The two oppsite reactions will however occur at differents speeds. At some poit there has been formed so much of the product, that the opposite reaction form the products back to the original substances occur equally much as the reaction forewards. At that point the system is in equilibrium and from that point on there will be no change in the ratios of products and original substances. Some reactions go far ahead so that there will be nearly no original substances left at equilibrium and some reactions do not go long before there will not be any net change in the blending any more. The products can however be taken away during the reaction, and then the process can continue until there are no otiginal reactant left. This occur for example when if the product is damped off or go up in the air because they are gasses.
About oxidation, reduction and fire
Originally oxidation simply denoted a process where oxygen makes bond with another substance. One used to say that the other substance got oxidized.
Reduction originally ment freeing a substance from a bond to oxygen. An example is the reduction of metal ore to make free metals.
When oxygen makes bonds, electrons tend to be pulled towards the oxygen atom so that the oxygen gets negatively loaded, and the other substance positively loaded. When oxygen bonds another substance, polar covalent or ionic bindings are thus formed.
Nowadays the term oxydation is used in a wider sense. Oxidation is defined as any chemical process that results in electrons being pulled away from an atom. This atom is said to be oxidized.
Reduction is defined as any chemical process in which elactrons are pulled towards an atom so that the atom gets negatively loaded.
Reduction and oxidation allways occur together, when one atom gets reduced, another gets oxidized. A process where reduction or oxidation occur is called a redox-process.
In the special case where oxygen binds to a substance, the substance is oxidized and oxygen is reduced.
Another special case is when a halogen, as for example chlorine, binds to some substance. The substance is also then oxidized, and the halogen is reduced. Clorine can for example bind to hydrogen to form HCL, or hydogen chloride, or chlorine can bind to the metal sodium to form NaCl or ordinary salt.
When two substances bind together in a redox-process, much energy tend to be released as heat. The heat can be so intense that the blending of substances begin to glow.
If a chemical process releases so much energy that the products are glowing, and some or all of the products are gasses, these glowing gasses will pour out from the reaction site and ascend up into the air. Such glowing gasses comming out of some process are called flames.
Any chenical or physical process that produces great amount of heat is called combustion, especially when the products of the process are simpler than the raw materials that go into the process.
Fire is glowing substances let out from such a process, especially when some of the substances are glowing gasses, or flames. In daily spech also the whole process is often called fire, instead of combustion.
When two substances of which one is in an oxidized state and the other in a reduced state, shall be separeted, much energy must usually be supplied, usually in the form of heat or electricity.
Such an example is when a free metal shall be produced from the ore. Then the ore must be heated, so that the binding between the oxidized metal and the reduced substance (usually oxygen) can be broken. In addition a helping substance (a so-called reducer) that the can take over the binding and thus be oxidixed instead is usually necessary. Carbon is often used as such a substance in the production of metals.
About chemical methods
When one intends to bring about a chemical reaction and harvest the resulting products, one generally use a specific sequence of steps.
First one has to measure up the right quantity and proportion of all reactants either by volumetric measurements or by veighting.
Then the reactants are blended in some kind of vessel or container.
Fore some exotherm reactions the blending itself is anough for the reaction to start, but generally one has to supply energy to start it and keep it running. This is done by heating, by letting an electric current go through the blending or by illuminating it with ordinary light or special frequencies.
Sometimes one also adds special helper substances to the blending, so called catalysts. A catalyst will take part in the reaction by dividing the reaction in two or more steps that easily occur, and thereby the overall reaction coours more easily. The helper substance will not be consumed or altered after the reaction.
Then the reaction products must often be separated and purified. If one of them is a gas, it can simply be led avay by holding the reaction vessel closed and have a tube leading the gas to another container. If one or more of them are liquids, those can be destilled out leaving solid products or less volantile liquids back in the original vessel. Products you do not want to keep can sometimes be damped off leaving the valuable products left. Sometimes it is possible to wash out one of the products with water or another solutant. Sometimes it is possible to make a product precipitate to the bottom of a container by adding salt. Sometimes you can burn away products you do not want to keep and thereby purifying the valuable parts.
The separation of the end products and the purification is often the most complicated part of a chemical process, and must often be done in several steps.
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