The number of electrons in an atom is not necessarily greater than the atomic number. In a neutral atom, the number of electrons is equal to the atomic number.
The atomic number of an element represents the number of protons in the nucleus of an atom, which also determines the element's identity. For example, carbon has an atomic number of 6, indicating that it has 6 protons in its nucleus.
In a neutral atom, the number of electrons is equal to the number of protons. This is because the positive charge of the protons is balanced by the negative charge of the electrons, resulting in an overall neutral charge for the atom.
However, it is possible for an atom to gain or lose electrons, forming charged particles called ions. When an atom gains electrons, it becomes negatively charged and is called an anion. In this case, the number of electrons is greater than the atomic number. Conversely, when an atom loses electrons, it becomes positively charged and is called a cation. In this case, the number of electrons is less than the atomic number.
For example, a carbon atom with 6 protons and 6 electrons is neutral. If it gains two electrons, it becomes a negatively charged ion called a carbide ion (C^(2-)). In this case, the number of electrons would be 8, which is greater than the atomic number of 6.
So, in summary, in a neutral atom, the number of electrons is equal to the atomic number. However, in ions, the number of electrons can be different, leading to a difference between the number of electrons and the atomic number.