Question

On an atomic scale what determines the elastic modulus of a material?

Answer 1

Answer-

Elasticity is defined as it is the ability of a material to return to its original shape and size after being stretched, compressed. To understand the elastic behavior and plastic behavior of material on the level of atoms requires first distinguishing between materials that are crystalline and those that are not.

the elasticity of any material depends upon the packing of atoms and molecules of that particular material to decide the elasticity of that material at atomic  scale level