What Is a periodic property ? How do the following properties change in a group and period ? Explain .
Ionization enery

Explanation

Periodic property :Periodicity means that when elements are arranged accoding to their electronic configuratiin , the properties of elements in the perioodic table reoccr at regular intervals - such properties which reoccur are called called as periodic properties
change of properties in a group and a period :

Ionization energy : The energy required to remove an electron from the outermost orbit or shell of a neutral gaseous atom is called ionization energy .
Variation in group : As we go down in a group atomic radius increases . hence the ionization energy decreases from top to bottom .
Variation in period : in period the value of ionization enthalpy increases from left to right with breaks where the atoms have somewhat stable configurations .