L-1 Atomic Structures

Material Science vs Material Engineering

Material science

• concerned with the search for basic knowledge about the internal structures, properties and processing of materials.

Material Engineering

• concerned with the use of fundamental
  and applied knowledge of materials that can be converted into products
  necessary or desired by society.

Bohr Model

electrons are assumed to revolve around
the atomic nucleus in a discrete orbital and the
position of any electron is well defined in terms of
its orbital.

Quantum Mechanics Model

Every electron in an atom is characterized by four parameters called quantum numbers. The
size, shape, and spatial orientation of electron’s
probability density are specified by quantum numbers.

Quantum Numbers

n = Principle Quantum Number

• (# of atomic shells)

l = subsidiary quantum number

• (# of sub-shells in main energy levels)

ml = magnetic quantum number

• (Specifies the spatial orientation of a single atomic orbital)

ms = Electron spin quantum number

• (specifies two allowed spin directions for an electron spinning on its own axis)

Chemical Bonds Between Atoms

• Primary (Strong) bonds
– Ionic bonding
– Covalent bonding
– Metallic bonding

• Secondary (Weak) bonds
– Van der Waals bonding
– Hydrogen bonding

Electronegative Elements

Elements which readily accept/share electrons to form negative ions

Electropositive ions

Elements that readily give away valence electrons to form positive ions