Difference between Atomic and Ionic size

Ionic Radius

The atomic and ionic radii of atoms differ. If an atom receives or loses an electron and becomes positively or negatively charged, it forms an ion. The atomic radius of a neutral atom equals its diameter. The radius of an atom can increase or decrease when it becomes an ion, and this is known as the atom’s ionic radius. The number of electrons acquired or lost can cause an element’s atoms to have differing ionic radii depending on whether they are a cation (positive ion) or an anion (negative ion).

Ionic radius and periodic table

As of the probabilistic wave function behaviour of electrons and the electron cloud, atoms have ambiguous sizes. Regardless, scientists calculate the diameter of atoms of various elements and model them as solid spheres. Other elements’ atoms are made up of varying amounts of subatomic particles and so have varying sizes. Ionisation also allows atoms to gain or lose their outermost electrons, increasing or decreasing their total size. Because electrons are negatively charged, they affect the charge of an atom when they receive or lose them. Ions are atoms that gain or lose electrons. When an atom receives or loses an outermost electron, the ionic radius describes the change in size (i.e., radius) (s). When an atom gets an extra electron, it transforms into a negatively charged ion known as an anion, which has a larger ionic radius. When an atom loses an electron, it transforms into a positively charged ion known as a cation, which has a smaller ionic radius.

Different elements’ ions can be isoelectronic, meaning they contain the same number of electrons. This does not, however, imply that they will have the same ionic radius. The nuclei of other elements have differing numbers of protons. Because protons have a positive charge, they have an effect on electrons who have a negative charge. The positive charge of an atom increases as the number of protons increases. As a result, they exert a stronger pull on electrons, drawing them closer together and reducing the atoms or ion’s total radius. The following ions, for example, have the same number of electrons and are thus in an isoelectronic series:

N3-,O2-,F–

As their varying numbers of protons, nitrogen (N), oxygen (O), and fluorine (F) can all gain various numbers of electrons and end up with the same number of electrons but distinct charges. The anions described above all have ten electrons, but because of their different protons, they have various negative charges. Furthermore, their nuclei have variable degrees of effect on their 10 electrons due to their different quantities of protons. As a result, each anion has a unique ionic radius. Nitrogen, for example, contains seven protons compared to eight for oxygen and nine for fluorine, hence nitrogen nuclei have a weaker attraction on their electrons and thus a bigger ionic radius. Because fluorine has the most protons in this series, it has the strongest influence on its ten electrons, pulling them tightly around the nucleus and reducing its ionic radius.

Atomic Radius Trend

The size of a neutral atom is measured in atomic radius. The periodic table of elements is set up in such a way that the atomic radius of each element follows a trend. On a periodic table, moving from the top right to the bottom left illustrates an increase in atomic radius.

The atomic radius trend across the periodic table is depicted in this diagram. When the ionisation energy trend is followed, it also shows an ionic radius trend.

Electronegativity is a measurement of whether an element’s atoms tend to lose electrons or rob atoms of their electrons. The energy necessary to remove an atom of its electrons is known as ionisation energy (s). The electronegativity or ionisation energy of an element is determined by its atomic radius. Atoms with a high electronegativity have tiny atomic radii and are found towards the periodic table’s top right corner. Because it takes more energy to strip an atom’s electrons, it has a higher ionisation energy and a stronger hold on its electrons. Because of this bond, these atoms have a tendency to steal electrons from other atoms with a lower electronegativity. With additional electron orbitals, the atomic radius grows greater, going down a group into higher periods. Additionally, atoms with more positively charged protons have a smaller atomic radius, which pulls their negatively charged electrons closer to the nucleus.

Electronegativity increases toward the top right of this periodic chart. The trend in atomic radius correlates with electronegativity.

Ionic Radius Trend

The radius of an atom when it receives or loses an electron and becomes an ion is called the ionic radius. The periodic chart also demonstrates how the ionic radius of atoms grows as the group number decreases.

Conclusion 

We conclude that when attempting to describe the behaviour of atoms or compounds, the size of atoms is critical. The atomic radius is one of the ways we can express the size of atoms. This information explains why some molecules fit together and why others have portions that get too crowded in certain situations.The radius of an atom in a crystal lattice is used to calculate its ionic radius. When electrons are extracted from a molecule, an ion smaller than the source element is formed. When electrons combine, they form a bigger ion than the source element.