Solution : . Those elements exhibit some properties of both metals and non-metals., these elements are called metalloids or semi-metals. In the Modern Periodic Table, a zig-zag line separates metals from non-metals. The borderline elements – boron, silicon, germanium, arsenic, antimony, tellurium and polonium – are intermediate in properties and are called metalloids or semi-metals.
Metallic and Non-metallic Properties Trends in the Modern Periodic Table The variation of metallic and nonmetallic properties along the period and along the group: Moving from left to right across a period in the periodic table results in a decrease in metallic character. This happens because atoms are more willing to accept electrons in order …
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Valency trend in Modern Periodic Table The valency trend Moving from the left to the right side of a period increases the number of valence electrons. The number of valence electrons stays constant within a group, even with this periodic trend.
Solution : Atomic Size Atomic size is the distance between the centre of the nucleus of an atom and its outermost shell. or, The shortest distance between the atom’s nuclei and the outermost shell of the atom. Atomic Radius The shortest distance between an atom’s nucleus and its outermost shell is known as the atomic …
THE MODERN PERIODIC TABLE In 1913, Henry Moseley showed that the atomic number (symbolised as Z) of an element is a more fundamental property than its atomic mass.Accordingly, Mendeléev’s Periodic Law was modified and atomic number was adopted as the basis of Modern Periodic Table and the Modern Periodic Law can be stated as follows:‘Properties …
MAKING ORDER OUT OF CHAOS – THE MODERN
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MENDELÉEV’S PERIODIC TABLE Dmitri Ivanovich Mendeléev, a Russian chemist. He was the most important contributor to the early development of a Periodic Table of elements wherein the elements were arranged on the basis of their fundamental property, theatomic mass, and also on the similarity of chemical properties. When Mendeléev started his work, 63 elements were …
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Dmitri lvanovich Mendeléev (1834-1907) Dmitri lvanovich Mendeléev was born in Tobolsk in Western Siberia,Russia on 8 February 1834. After his early education, Mendeléevcould join a university only due to the efforts of his mother. Dedicating his investigations to his mother he wrote, “She instructed with example, corrected with love and travelled with me to places …
Newlands’ Law of Octaves The attempts of Döbereiner encouraged other chemists to correlate the properties of elements with their atomic masses. In 1866, John Newlands, n English scientist, arranged the then known elements in the order of increasing atomic masses. He started with the element having the lowest atomic mass (hydrogen) and ended at thorium …
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Döbereiner’s TriadsIn the year 1817, Johann Wolfgang Döbereiner, a German chemist, tried to arrange the elements with similar properties into groups.He identified some groups having three elements each. So he called these groups ‘triads’. Döbereiner showed that when the three elements in a triad were written in the order of increasing atomic masses; the atomic …
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We have been learning how various things or living beings can be classified based on their properties. Even in other situations, we come across instances of organisation based on some properties. For example, in a shop, soaps are kept together in one place while biscuits are kept together elsewhere. Even among soaps, bathing soaps are …
