Is the trend for ionic radius just that for metals, they are smaller than the nuetral atom and for non-metals, and for non-metals, they are bigger than the neutral atom?

Or is there another specific trend?

The trend for ionic radius is more nuanced than simply being smaller for metals and larger for non-metals. The ionic radius is the measure of the size of an ion in an ionic compound.

When a metal atom loses electrons to form a positive ion (cation), its ionic radius is generally smaller than its neutral atom. This is because the loss of electrons reduces the electron-electron repulsion, causing the remaining electrons to be pulled closer to the nucleus, resulting in a smaller atomic radius. So, in general, you are correct that for metals, the ionic radius is smaller than the neutral atom.

On the other hand, when a non-metal atom gains electrons to form a negative ion (anion), its ionic radius is generally larger than its neutral atom. This is because the extra electrons increase the electron-electron repulsion, causing the electron cloud to spread out, resulting in a larger atomic radius. Therefore, for non-metals, the ionic radius tends to be larger than the neutral atom.

However, it's important to note that there are exceptions to this trend. For example, in some cases, the addition or removal of electrons might lead to changes in the electronic structure or the presence of different electron configurations, which can affect the overall size of the ion. The specific trend for ionic radius may also depend on factors such as the specific element, its charge, and the size and charge of the surrounding ions in the crystal lattice.

To determine the trend for ionic radius, it is important to consult the periodic table and consider the overall behavior of the elements. Additionally, examining experimental data, scientific literature, and studying the properties of specific elements and their ions can provide more insights into the trends in ionic radii.