Define chemical twins and write general electronic configuration of actinides
Answers
Chemical twins are those in which the properties of some elements are same. Atomic size of Zr and Hf , Nb and Ta are similar. This is due to Lanthanide contraction.
The general electronic configuration of actinium is [Rn] 5f0-14 6d0-2 7s2 where Rn is the electronic configuration of the element Radium.
A chemical element is any material that cannot be broken down or changed by chemical means. There are 118 known chemical elements. These chemical elements are the building blocks of matter. All chemical elements are arranged in the periodic table of elements, in the order of increasing atomic number. There are also four groups of elements in the periodic table: s block, p block, d block and f block. Elements are grouped into these groups based on their electron configurations. For example, s block elements have their outermost electrons in an s orbital. p block elements have their outermost electrons in a p orbital. The main difference between d block elements and f block elements is that d block elements are chemical elements having electrons filled to their d orbitals whereas f block elements are chemical elements having electrons filled to their f orbitals.