NOTHIN !
they have the same energy levels
Elements at the center of a period tend to have the highest electronegativity and smallest atomic radii compared to the other elements in the period. Additionally, these elements often possess a stable electron configuration.
Three electrons in their valency orbit.
Elements in the 4th period of the periodic table all have four energy levels or shells in their atomic structure. They belong to the same block (s and p) and exhibit similar chemical properties in terms of reactivity and bonding. Elements in this period include potassium, calcium, scandium, titanium, and iron.
Period 1: 2 elements Period 2: 8 elements Period 3: 8 elements Period 4: 18 elements Period 5: 18 elements Period 6: 32 elements Period 7: 25 elements
A period is a row of elements
Elements at the center of a period typically have the highest number of electron shells among the elements in that period. They also tend to have properties that are intermediate between metals and nonmetals. Additionally, elements at the center of a period may exhibit a balance between atomic size and effective nuclear charge.
Their valence electrons are in the same energy level.
Elements in the same group have more in common because they have the same number of valence electrons, leading to similar chemical properties. Elements in the same period have increasing atomic numbers and electron shells, but their properties can vary widely due to different numbers of electron shells and arrangements.
All of these elements belong to same period. The period number is 3.
All elements comprising the period 7 in the periodic table are radioactive. In total this period has 32 elements.
Rows of elements are called periods. The period number of an element signifies the highest unexcited energy level for an electron in that element. Columns of elements help define element groups. Elements within a group share several common properties. Groups are elements have the same outer electron arrangement.