Here,I will give you the ever best concept of Atomic size and Atomic radii. In thiss video, I will tell you: 1) Atomic size and atomic radii in the periodic table 2) Atomic radius trends on periodic table | Periodic table | Chemistry | 3) Periodic Trends: Atomic Radius 4) The Periodic Table: Atomic Radius, Ionization Energy, and Electronegativity 5) Periodic Trends in Atomic Size Atomic size is defined interms of atomic radius. Atomic radius means the distance of valence electron from the centre of an atom or nucleus. Atomic size and atomic radii can not be even determined by a powerfull optical microscope. But techniques have been developed to measure the atomic size and atomic radii. Like we find the covalent radius of a molecule then half of the covalent radius is know as atomic radius. When you move from left to right in a periodic table the atomic size and atomic radii decreases. The reason for this is: - The number of protons increase - the number of shells remain the constant Due to which the nuclear attraction on the valence electrons increases. Hence atom becomes condensed, and atomic size and atomic radii decreases. When you move from top to bottom in periodic table the atomic size and atomic radii increases, this is because: - The number of protons are increasing - The number of shells are increasing Due to which the atomic size and atomic radii increases. If we talk about the ionic radii then the cationic radius of ion is always smaller the a neutral atom. This is due to the imbalance of electronic and protonic ratio. In cation, the number of protons are greater then the number of electrons. Therefore nuclear attractions on electrons increase and, atomic size and atomic radii decrease. If we talk about the anionic radii of tis always hen anionic radnumbii is always greater then the neutral atom. this is because the imbalance of the electronic and protonic ratio. In anion, the number of protons is smaller then thenumber of electrons. Therefore nuclear attrctions decrease on electrons and, atomic size and atomic radii decrease. Subscribe my channel at: https://www.youtube.com/channel/UC_ltCdLVMRZ7r3IPzF2Toyg https://www.facebook.com/Najamacademy/ https://www.youtube.com/channel/UC_ltCdLVMRZ7r3IPzF2Toyg