Q. 474.8( 4 Votes )
Mendeleev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.
(a) Name the elements which have taken the place of these elements.
(b) Mention the group and the period of these elements in the Modern Periodic Table.
(c) Classify these elements as metals, non-metals or metalloids
(d) How many valence electrons are present in each one of them?
(a) The two elements that have taken the place of Eka-silicon and Eka-aluminium are Germanium (Ge) and Gallium (Ga), respectively.
(b) Germanium is placed in Group 14 and Period 4 in the Modern Periodic Table.
Gallium is placed in Group 13 and Period 4 in the Modern Periodic Table.
(c) Germanium (Ge) is metalloid. Gallium (Ga) is a metal.
(d) Valence electrons in Germanium (Ge) are 4. Valence electrons in Gallium (Ga) are 3.
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F, Na, Mg, Al, Si, P, S, Cl, Ar, K
i. Pick two sets of elements which have similar properties.
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(b) Name the scientist who first of all showed that atomic number of an element is a more fundamental property than its atomic mass.
(c) State Modern periodic law.
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(ii) Name the element which is a metal with valency three.
(iii) Name the element which is a non-metal with valency three.
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