Question

answer this question ​

Answer 1

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Because atomic number is only varies for one element but there would be different elements have atomic mass close to the other element or we have to put them in between the elements for which there is no space in the periodic table . so atomic no. is more appropriate than atomic mass.

1) metallic properties decreases from going left to right.

2) metallic properties increases from going

up to down.

Answer 2

It has many reasons one of them is isotopes of an element would have to give seperate places to each of them