Question

13) In the modern periodic table. The elements are arranged in accordance with their А) names B) atomic numbers C) atomic mass numbers D)densities​

Answer 1

B) Atomic numbers

Modern perodic table is based on atomic numbers.

Explanation:

Modern perodic table: Henry Moseley , gave a new property of elements , ' atomic number' and this was adopted as the basis of Modern perodic table.

Modern perodic Law

• Properties of elements are perodic functions of their atomic number.

Position of elements in modern perodic table

• The modern perodic table consists of 18 groups and 7 periods .
• Elements present in any one group Have the same number of valence electrons. Also the number of shells increases as we go down the group.
• Elements present in any one period , contain the same number of shells. Also with increase in atomic number by one unit on moving from left to right , the valence shell electrons increases by one unit.
• Each period marks a new electron shell getting filled.

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Answer 2

B) atomic numbers

Explanation:

• In the modern periodic table, the elements are arranged according to their atomic numbers.
• They are arranged into rows called periods in increasing order of atomic number.