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.

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.

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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What is physics?

Physics is the sicence about the basic building blocks in the nature, the elementary particles. It is also the science of the most basic properties of matter. Such properties are mass, charge momentum, and elementary particles properties called charm, color and spin.

It is also the science about the forces in the nature and the laws gowerning their behaviour. These forces work on both the cosmological level, the everyday macroscopic level, the microscopic level and the elementary particle level.

A force is actually an event that leads to the exchange of energy between two particles, so that one of them loose velocity and the other gain velocity. Forces in the opposite direction can however work against each other so that the net energy exchange dimmishes or is zero.

The forces are of many kinds, for example gravity, electromagnetic force, strong force and weak force. In dayly life only electromagnetic forces and garvity are directly observed. The other forces belong to the elementary particle world only because they only work over a short distance.

A certain force can only work between tho objects if the objects have the same special kind of propery. Mass makes it possible for two objects to attract each other with gravity. Electric charge is necessary for electromagnetic force. Some forces exist in two or theree variants, for example exists the electromagnetic charge as negative and positive charges. The chrarge of particles interacting determines the direction of the force. The same charge effect repulsing force, opposite charges result in attracting force.

These forces are basically the same at all the size levels, but certain aspects of them have most impact on the cosmological level and high energy level and certain of them have most impact on very small scales.

It is very impractical to take concideration of all the aspects every time you have to compute some force and their result, and one has not yet managed to develop any theory that take into concideration all aspects simultanously. Therefore one usually applies theories that only take into concideration the most important aspects.

On very large scales, great velocities and on very great anergy levels one uses the theory of relativity. On everyday calculations one uses Newtonian physics that is the most simple of them. On the elementary particle level quantum mechanics is the theory used.

The theory of relativity takes into concideration the relativistic aspects. These tell that such things as length, time and mass appear to change when the velocity of an observed object is very great. Length contracts according to the measures, time slows and the mass increases and goes to infinity when the velocity approches the velocity of light. Therefore no object can reach or exceed the velocity of light according to the standard theory of relativity.

Quantum mechanic tells that the forces are statistic. No exchange of energy is certain to happen, but has only a certain chance that vary from situation to situation. Also it is not possible to know exactly where an object is, there is only a chance for the object to exist at certain places, but varying from place to place. Some places are however very probable and other very unlikely. This statistic behaviour is however mostly observed at the elementary particle level. At greater levels, the chances of of the results from all the elementary particle the object conssists of sums to a nearly certainty of observing a force with a certain strength and observing the object at one particular place.

When the situation gradually changes from those where relativistic and quantum effects are easily found to the scales observed at everyday situations, the results calculated from the theory of relativity and quantum mechanics gradually appoach the results one can obtain from Newtonian mechanics.

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