INTRO TO MATERIALS Flashcards
electrostatic interactions between molecules. are usually much weaker than the intramolecular forces
intermolecular forces
When the electronegativity difference between bonded atoms is moderate to zero, i.e., usually less than 1.9, the bonding electrons are shared between the bonded atoms, as illustrated in Fig. 3.9.4. The attractive force between the bonding electrons and the nuclei is the [] that holds the atoms together in the molecules. The [] is usually weaker than the metallic and the ionic bonds but much stronger than the intermolecular forces.
covalent bond
Metals tend to make the [] with each other. Metals also tend to have lower electronegativity values. So, when the average electronegativity of the bonded atom is low and the electronegativity difference between them is also low, they tend to make a [].
metallic bond
is the ability of the material to conform to its intended purpose
performance
Polar molecules have permanent dipoles, one end of the molecule is partial positive (δ+) and the other is partial negative (δ-). The polar molecules have electrostatic interactions with each other through their δ+ and δ- ends called [], though these interactions are weaker than ionic bonds. The polar molecules orient in a way to maximize the attractive forces between the opposite charges and minimize the repulsive forces between the same charges
dipole-dipole interactions
[] stress is the stress state caused by an applied load that tends to elongate the material along the axis of the applied load, in other words, the stress caused by pulling the material. [] or [] is a limit state of [] stress that leads to tensile failure in the manner of ductile failure or brittle failure.
tensile strength
Tensile
ultimate tensile strength
Relatively weak, tend to be
Soft, have low melting points
Molecular solids
is the method by which a material undergo for its manufacture.
process
a physical object that is made of one or more substance(s)
materials
Held together by the intermolecular forces: dispersion forces, dipole–dipole interactions, and hydrogen bonds
Molecular solids
Held together by a delocalized “sea” of collectively shared valence electrons
Metallic solids
[] tend to have lower electronegativity and [] have higher electronegativity.
Metals
nonmetals
are composed of one or more metallic elements
metals
There is the electrostatic interaction between cation and anion, i.e., the same charges attract each other, and opposite charges repel each other. The cations and anions orient themselves in a 3D crystal lattice in such a way that attractive interactions maximize and the repulsive interactions minimize. [] are usually weaker than metallic bonds but stronger there the other types of bonds.
Ionic bonds
the ability of a material to return to its previous shape after stress is released.
Elasticity
a material can be plastic deformed and shaped when cold. A [] material can be plastic shaped with hammering or rolling without fracture.
Malleability
is a material trait in terms of the kind and magnitude of response to a specific imposed stimulus.
property
the resistance to compressive stress which is caused by an applied load that acts to reduce the length of the material along the axis of the applied load, in other words, a resistance from squeezing the material.
Compressive Strength
forces caused by correlated movements of the electrons in interacting molecules, which are the weakest of intermolecular forces and are categorized as van der Waals forces.
london dispersion or dispersion forces
When the electronegativity difference is low, usually less than 1.9, the bond is either [] or []
metallic or covalent.
The forces holding ions together in ionic solids are electrostatic forces. Opposite charges attract each other. These are the strongest intermolecular forces. [] hold many ions in a crystal lattice structure.
Ionic forces
