Meaning and mechanism
An atom is neutral when it has equal numbers of positively charged protons and negatively charged electrons. Losing electrons leaves a positive ion, while gaining electrons produces a negative ion.
When a sodium atom loses one electron, it becomes Na⁺. When a chlorine atom gains one electron, it becomes Cl⁻, and this process is distinguished from nuclear reactions.
Relationships and conditions
The elementary charge of an ion is p−e. If there are 12 protons and 10 electrons, the result is +2, and if you add two more electrons, it becomes neutral.
Representing electron arrangement as a simple shell model does not determine the stability or formation energy of all ions. When considering the transferred electrons, the total charge is preserved.
What to observe in the simulation
If it loses an electron, it becomes a positive ion, and if it gains an electron, it becomes a negative ion. The element does not change due to electron transfer.
The shell is a schematic diagram for counting electrons and is not the actual shape of electrons rotating in circular orbits. Storage and movement paths are for illustration purposes only. Ionization energy, electron affinity, and reaction spontaneity are not calculated.
Key relationships and symbols
Ionic charge = number of protons − number of electrons
| Symbol | Meaning | Unit |
|---|---|---|
| p | Number of protons | items |
| e | Number of electrons | items |
| q/e₀ | Ion charge in elementary-charge units | Dimensionless |
Worked example
What is the number of electrons and charge after Mg loses 2 electrons?
Mg has 12 protons and 10 electrons, so its charge is +2e.
Common misconceptions
- The process of becoming an anion is not about acquiring new protons, but rather about losing electrons.