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PREDICTIONS OF NEW ELEMENTS
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To place similar elements in the same group, Mendeleef left many vacant spaces in his table. For example,
Next to calcium (atomic mass 40) should be titanium (Atomic mass 48) but it resembled silicon(atomic mass 28) instead of aluminum (atomic mass 27). Hence Mendeleev predicted that an element, resembling Al, was still to be discovered whose atomic mass should be the average of atomic masses of Ca and Ti. i e (40 + 48) / 2 = 44. In 1875 this element was discovered and was named as Gallium. In this way Mendeleef not only predicted the undiscovered elements but also guessed their atomic masses and properties as well.
In 1886 the element Germanium (atomic mass 72.6) was discovered whose oxide and chloride had the formulas GeO2 and GeCl2 respectively. Its valency was calculated as 4 and was placed in the fourth group.
Next to calcium (atomic mass 40) should be titanium (Atomic mass 48) but it resembled silicon(atomic mass 28) instead of aluminum (atomic mass 27). Hence Mendeleev predicted that an element, resembling Al, was still to be discovered whose atomic mass should be the average of atomic masses of Ca and Ti. i e (40 + 48) / 2 = 44. In 1875 this element was discovered and was named as Gallium. In this way Mendeleef not only predicted the undiscovered elements but also guessed their atomic masses and properties as well.
In 1886 the element Germanium (atomic mass 72.6) was discovered whose oxide and chloride had the formulas GeO2 and GeCl2 respectively. Its valency was calculated as 4 and was placed in the fourth group.
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