what makes the center of an atom stable
Atom The electrons in an atom are attracted to the protons in the nucleus by the electromagnetic force. This force binds the electrons inside an electrostatic potential well surrounding the smaller nucleus, which means that an external source of energy is needed for the electron to escape. The closer an electron is to the nucleus, the greater the attractive force. Hence electrons bound near the center of the potential well require more energy to escape than those at greater separations.
Tetrahedral molecular geometry In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are cos−1(−⅓) = 109.4712206...° ≈ 109.5° when all four substituents are the same, as in methane (CH4)[1][2] as well as its heavier analogues. The perfectly symmetrical tetrahedron belongs to point group Td, but most tetrahedral molecules have lower symmetry. Tetrahedral molecules can be chiral.