摘要
What decides the properties of materials?Finding answers to this question leads us to the fundamental nature of atomic bonding determined by electrons.For example,electron transfer from one atom to another forms an ionic bond that is common for brittle ceramics.When two adjacent atoms share valence electrons,a highly directional covalent bond is formed,providing a strong physical property.Moreover,the unfilled valence band and the states,movements,and behavior of electrons in metals are attributed to many properties such as high electric and thermal conductivity and unique shiny optical features.Therefore,to understand and predict the properties of materials,it is important to characterize and understand the material at the atomic level.
