Here's why:

* Atomic Number: The number of protons in an atom's nucleus defines its atomic number. This number is unique to each element.

* Neutral Atoms: In a neutral atom, the number of protons (positive charge) is equal to the number of electrons (negative charge). This ensures a balanced charge.

Therefore, all atoms of a specific element have the same number of electrons. For example, all carbon atoms have 6 electrons, all oxygen atoms have 8 electrons, and so on.

Exceptions:

* Ions: Atoms can gain or lose electrons to become ions. This changes the number of electrons, but the element's identity remains the same. For example, a chlorine atom (Cl) has 17 electrons, but a chloride ion (Cl-) has 18 electrons.

* Isotopes: Some elements exist as isotopes, which are atoms of the same element with different numbers of neutrons. While the number of neutrons varies, the number of protons and electrons remains the same.

In summary: The number of electrons in a neutral atom of a specific element is determined by its atomic number and remains consistent.