valence electron trend on periodic table

However, there are also other patterns in chemical properties on the periodic table. This similarity occurs because the members of a group have the same number and distribution of electrons in their valence shells. The elements in groups (vertical columns) of the periodic table exhibit similar chemical behavior. Describe and explain the observed trends in atomic size, ionization energy, and electron affinity of the elements.For both IE and electron affinity data, there are exceptions to the trends when dealing with completely filled or half-filled subshells.īy the end of this section, you will be able to:

Therefore, electron affinity becomes increasingly negative as we move left to right across the periodic table and decreases as we move down a group. Electron affinity (the energy associated with forming an anion) is more favorable (exothermic) when electrons are placed into lower energy orbitals, closer to the nucleus. Ionization energy (the energy associated with forming a cation) decreases down a group and mostly increases across a period because it is easier to remove an electron from a larger, higher energy orbital. Anionic radii are larger than the parent atom, while cationic radii are smaller, because the number of valence electrons has changed while the nuclear charge has remained constant. Covalent radius mostly decreases as we move left to right across a period because the effective nuclear charge experienced by the electrons increases, and the electrons are pulled in tighter to the nucleus.

Covalent radius increases as we move down a group because the n level (orbital size) increases. Electron configurations allow us to understand many periodic trends.

Valence electron trend on periodic table