Looking across period 4 of the periodic table, potassium (atomic number 19) is followed by calcium (atomic number 20), which is followed by scandium (atomic number 21). which element should have the largest atomic radius?

Potassium should have largest atomic radius

'cause on moving to right, attractive force between nucleus and electrons increases and causes shielding effect, due to which atomic radius get smaller

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates