4/13/2024 0 Comments The atomic theory![]() ![]() This word comes from the Ancient Greek adjective atomos, meaning “ indivisible“. They supposed that the properties of materials were determined by the different shapes and forms of their atoms. The word “atom” was coined by the ancient Greek philosophers Leucippus, Epicurus and Democritus. These ancient philosophers speculated that the earth was made up of different combinations of basic substances, or elements. It must be added, atomism was one of a number of competing theories on the nature of matter. Atomic theory began as a philosophical concept in ancient Greece and India. A scientific theory, which deals with the nature of matter is known as atomic theory. But the path to this model was complex and full of many surprising findings. This model is today quite clear and proven. The nucleus itself is generally made of protons and neutrons. The electrons are spinning around the atomic nucleus. The atoms are the smallest constituents of ordinary matter, which can be divided without the release of electrically charged particles. The vertical columns have similar properties within their group for example Lithium is similar to sodium, beryllium is similar to magnesium, and so on.As was written, all matter except dark matter is made of molecules, which are themselves made of atoms. The table below shows that elements increase from left to right accordingly to their atomic number. The periodic law is found to help determine many patterns of many different properties of elements melting and boiling points, densities, electrical conductivity, reactivity, acidic, basic, valance, polarity, and solubility. Thus, we can see that elements are arranged based on their atomic number. 39.1, respectively), yet argon is in front of potassium. As mentioned before, argon weights more than potassium (39.9 vs. Similar properties recur periodically when elements are arranged according to increasing atomic number."Ītomic numbers, not weights, determine the factor of chemical properties. With Moseley's contribution the Periodic Law can be restated: Moseley was able to tie the X-Ray frequencies to numbers equal to the nuclear charges, therefore showing the placement of the elements in Mendeleev's periodic table. ![]() Moseley did researched the X-Ray spectra of the elements and suggested that the energies of electron orbitals depend on the nuclear charge and the nuclear charges of atoms in the target, which is also known as anode, dictate the frequencies of emitted X-Rays. Elements were placed into groups that expressed similar chemical behavior. An example of this was with argon (atomic mass 39.9), which was put in front of potassium (atomic mass 39.1). Explaining that a given set of properties reoccurs every eight place, he named it the law of Octaves.Ītomic Number as the Basis for the Periodic LawĪssuming there were errors in atomic masses, Mendeleev placed certain elements not in order of increasing atomic mass so that they could fit into the proper groups (similar elements have similar properties) of his periodic table. R Newland arranged the elements in increasing of atomic weights. This gave scientists the tools to reveal the relationships between elements. In 1859 two physicists Robert Willhem Bunsen and Gustav Robert Kirchoff discovered spectroscopy which allowed for discovery of many new elements. However, at the time of this discovery too few elements had been discovered and there was confusion between molecular weight and atomic weights therefore, chemists never really understood the significance of Doberiner's triad. By 1829, chemist Johann Wolfgang Doberiner observed that certain elements with similar properties occur in group of three such as chlorine, bromine, iodine calcium, strontium, and barium sulfur, selenium, tellurium iron, cobalt, manganese. Around the same time, two chemists Sir Humphry Davy and Michael Faraday developed electrochemistry which aided in the discovery of new elements. In 1804 physicist John Dalton advanced the atomic theory of matter, helping scientists determine the mass of the known elements.
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