This course focuses on the chemistry and physics of engineering materials (metals, alloys, and polymers) from the point of view of a mechanical engineer. Emphases are put on atomic or molecular interpretation of physical or mechanical properties, the relationships between physical and chemical properties and performance of engineering materials. Topics covered include atomic structure and bonding in solid materials, crystalline structures, microstructures of the engineering materials, and an introduction to X-ray diffractometry that enables us to measure the crystalline structure (atomic arrangement) of solid materials. Over the course we will discuss how the atomic structure or its arrangement in solid materials determines the macroscopic properties of the materials such as tensile strength.