the atomic number of Cd is 48
atomic number gives the number of protons in the atom
elements in their ground state, the number of protons is equal to the number of electrons
therefore number of electrons is 48
the condensed electronic configuration is [Kr} 4d¹⁰ 5s²
the outermost energy shell is the 5th energy shell with 2 electrons in the 5s subshell.
Valence electrons are the electrons in the outermost energy shell that are involved in chemical bonding.
there are 10 electrons in the 4d subshell however 4th energy shell is not the outermost energy shell therefore these electrons are not regarded as valence electrons
In Cd there are 2 electrons in the outermost energy shell therefore Cd has 2 valence electrons.
answer is 2
