Question
Can there be an element with atomie mass 53 or 54 in between the two elements, chromium ${ }_{24}^{52} Cr$ and manganese ${ }_{25}^{55} Mn$ ?
✓
Answer
In Mendeleev's periodic table, the difference between atomic masses of two consecutive elements is not the same $\left({ }^{52} Cr\right.$ and $\left.{ }^{55} Mn \right)$. Moseley found out the atomic number of the elements. The atomic number of any element is increased by one unit (number) from the atomic number of subsequent element. ${ }_{24}^{52} Cr \rightarrow{ }_{25}^{55} Mn$ that means in between two elements ( $Cr$ aind $Mn$ ), element with mass 53 or 54 do not exist.
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