The atom you described has 12 electrons and an atomic mass of 25. Based on this information, we can determine the approximate electron configuration and draw its electronic structure.
The atomic number of an element corresponds to the number of electrons in a neutral atom. Since you mentioned the atom has 12 electrons, we can identify the element as magnesium (Mg), which has an atomic number of 12.
The electron configuration of magnesium is 1s² 2s² 2p⁶ 3s². This configuration indicates that the first energy level (n=1) contains 2 electrons in the 1s orbital, the second energy level (n=2) contains 8 electrons with 2 in the 2s orbital and 6 in the 2p orbital, and the third energy level (n=3) contains 2 electrons in the 3s orbital.
Now, let's draw the electronic structure of magnesium: