Chapter One Flashcards
What are some engineering materials?
Metals, ceramics, polymers, composites, and advanced materials.
What is the atomic structure of metals?
They have a metallic bond. The atomic structure is relatively dense in comparison to ceramics and polymers.
What are the thermal properties of metals?
They have high thermal conductivity and a relatively large thermal expansion.
What are the electrical properties of metals?
They have a high electrical conductivity (low resistance, electrons are free to move).
What are the optical properties of metals?
They are opaque to visible light.
What is the atomic structure of ceramics?
Ceramics have ionic and covalent bonds. The atomic structure is relatively denser than polymers.
What are the thermal properties of ceramics?
They have a low thermal conductivity and small thermal expansion. They have high operating temperatures and are therefore resistant to heat.
What are the electrical properties of ceramics?
They have a low electric conductivity (high resistance, electrons are bonded to atoms).
What are the optical properties of ceramics?
They can be opaque, translucent, or transparent.
What is the atomic structure of polymers?
They are covalent and have secondary atomic bonds. The atomic structure has a low density.
What are the thermal properties of polymers?
They have a low thermal conductivity and small thermal expansion. They have low operating temperatures (are prone to heat).
What are the electrical properties of polymers?
They have a low electrical conductivity (high resistance, electrons are bonded to atoms).
What are the optical properties of ceramics?
Could be opaque, translucent, or transparent.
What are the mechanical properties of metals?
They are strong, stiff, and ductile.
What are the mechanical properties of ceramics?
They are strong, stiff, and brittle.
What are the mechanical properties of polymers?
They have low strength and stiffness and are ductile.
How does one measure stiffness?
Change in force over change in dimension.
Discuss ductility vs brittleness.
Ductility is deformation. Since metals and polymers are ductile. the will deform before failure whereas ceramics will not deform before failure. If you break a mug (ceramic) and put it back together, the dimensions remain the same. But, if you rip apart a gummy worm (representing polymers and metals), before ripping, it will stretch. This is ductility before failure.
What is the electron to proton comparison in atoms?
The number of electrons and protons are the same.
Why is the nucleus always positive?
Because it only contains protons and neutrons.
What is the proton to electron comparison in cations?
There are more protons than electrons.
What is the proton to electron comparison in anions?
There are less protons than electrons.
What are atoms and what are they made of?
They are considered to be the primary block of a material structure and are made of 3 subatomic particles: protons, neutrons, and electrons.
What is an electron?
An electrically charged particle that moves inside an atom. It has a negative charge (1.602e-19 C) and a small mass (9.11e-31 kg).
