What happens to the size of an atom when it becomes a negative ion? Why?
Generally it gets larger because the electrons are going into the outside shell where there are electrons already and the negative charges repel each other.
Thank you!
When an atom becomes a negative ion, its size generally increases. This happens because the atom gains one or more extra electrons, which increases the electron-electron repulsion within the atom. This increased repulsion causes the electron cloud to expand, effectively increasing the size of the ion.
To understand why this happens, let me explain a bit of atomic structure. Atoms consist of a nucleus at the center, which contains protons and neutrons, surrounded by a cloud of electrons in different energy levels or orbitals. The electrons, which carry negative charge, are held in place by the positively charged nucleus through electrostatic forces.
In a neutral atom, the number of electrons is equal to the number of protons in the nucleus, resulting in overall charge balance. However, when an atom gains one or more extra electrons, it becomes negatively charged. The additional electrons start to occupy the outermost energy levels or orbitals of the atom, pushing against the existing electrons and increasing the overall electron-electron repulsion.
This repulsion weakens the attractive forces between the electrons and the nucleus, making it easier for the outermost electrons to "spread out" and occupy more space. As a result, the electron cloud expands, causing the size of the atom to increase when it becomes a negative ion.
It is important to note that the size increase may vary depending on the specific atom and the number of extra electrons gained. In some cases, particularly if the additional electrons are added to an already more extended orbital, the size increase may be more significant.