Question

summary of cha 5 chemistry 10 class. plzz friends. with table explaination.​

Answer 1

Answer:

Revision Notes on Periodic Classification of Elements

Placing similar groups and species together is known as Classification. Classification is needed to easily understand the properties of different elements in a periodic table. Elements with similar properties are placed in one group to understand them easily.

Dobereiner’s triad consider three elements, in which atomic mass of central element is the arithmetic mean to two other elements. For Example, Atomic masses of lithium, sodium and potassium are 7, 23 and 39. The arithmetic mean of 7 and 39 gives 23. But disadvantage is the presence of only few triads.

Dobereiner’s Triad

Newland’s Law of Octave say that elements are arranged in such a way that every eight element has same properties as in the first element. According to him, only 56 elements are found which is a drawback of Newland Law of Octaves. This was not accepted. It is acceptable only upto calcium. He also placed some unlike elements in the same slot.

Newland’s Law of Octave

Mendeleev’s Periodic Table

Mendeleev used atomic masses as the basis of arrangement of elements. According to him, elements were arranged in increasing order of their atomic masses. It believes that there was a periodic reappearance in their physical and chemical properties.

Explanation:

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