Human memory is built on associative and logical connections.Therefore it is so important for us to organize reality, to distribute its components on the cell and find a system.Otherwise, the memory refuses to listen, and the mind - to analyze.It is no coincidence in the history of chemistry in such an important breakthrough is the creation of the periodic table - the order, the system and the logic prevailed.The impact of this discovery was so great, that has inspired many.For example, Lyubishchev genius Russian time management, has developed its own system in order to create a periodic table of living organisms.This goal was not achieved, but the very fact proves the importance for the understanding of human logic.But the reality is richer beautiful circuits.For example, in the main table of chemistry some elements are out of order by weight.Why is that?You can reply with one word - "isotopes".This word literally means "to occupy one place."
work a lot, remember not all
Periodic Table - the fruit of hard work by many scientists, and not only its creator.He brilliantly created the principle and found the basic laws.But the mass of the figure that you see under each element - the fruit of the work of many chemists, and in addition, it is inaccurate.How can this be?Did you ever pay attention to what the atomic number - beautiful integer.But the mass - fraction with a huge number of decimal places.Why is that?And to blame the same isotopes.This can be explained quite simply.If you look at the figures for the element "nitrogen", near the atomic mass numbers you see 14.0067.However, if you "catch" a free nitrogen atom, it can weigh and 10, and 25 atomic units.Various they are.And what's the difference?Isotope mass consists of the mass of the proton and the neutron mass.The mass of the protons - a constant value, it makes it an element (nitrogen - nitrogen).But neutrons of atoms can be both rich and poor.In the example of nitrogen there may be 18, and only 3 pieces.Isotopes - this kind of atoms the element depending on the number of neutrons in the nucleus.We found 16 isotope of nitrogen.Some other elements of the case and more.
What scientists do?
If you were scientists, what would you do?How you would have recorded a lot to the table for the calculation?One could, of course, take the arithmetic mean.But many isotopes - is very unstable objects, some of them - artificially created.Therefore, it would be wrong to carry out calculations with a focus on inaccurate data.Scientists do otherwise - they have calculated the atomic weight of an element is proportional to the natural abundance of an isotope.As a result, the probability that an arbitrary search you hit it in the isotope 14 mass units is very high.The nucleus of the isotope found randomly likely to contain seven protons and seven neutrons.
Reasons inaccuracies
Why is the atomic mass is not completely accurate?Because the output of it is made inductively - from private to general.We do not know the exact composition of the Earth under the crust, we have not explored geologically even just the entire surface of the Earth.Therefore, the atomic mass number - the probability.It is based on the knowledge that people have today.Why do scientists is satisfied?Because greater accuracy is needed only for molecular physics to calculate the number of trivial error can be ignored.But the violation of the order by weight obyanyaetsya that it is important for the chemical properties of the number of charged particles - protons.And it is by the number of protons and the elements are arranged in series.
