An element forms a negative ion when ionized. what side of the periodic table is it located on?

Mendeleev's periodic table was in error because when the elements were arranged by mass it resulted in several elements being placed in groups of elements with differing properties.

Because a model would make the investigation easier to understand

Ch4 and ph3 are both covalent since they are composed both of non-metals.    ch4 is non- polar because of  london forces and has a geometry of tetrahedral  ph3 , on the other hand, is umbrella shaped polar and has dipole-dipole intermolecular force (imf) . since ph3 is polar, it has a stronger imf