Materials Science: Why Old Glass Is Not a Slow Liquid
Why materials behave as they do, from atoms and crystal defects to quenched swords, cracking ships, stretchy plastics, tempered glass and rust.
Try 3 questions
1. Why are metals such good conductors of electricity?
- Their nuclei carry more charge
- Their atoms are packed very tightly
- Their outer electrons roam freely
Show the answer
Answer: Their outer electrons roam freely
In metallic bonding, valence electrons are shared across the whole crystal as a 'sea' that moves easily when a voltage is applied.
2. Diamond and graphite are both pure carbon. Why is one the hardest natural material and the other soft enough for pencils?
- Diamond formed under far colder conditions
- Graphite contains much more impurity
- Their atoms are bonded and arranged differently
Show the answer
Answer: Their atoms are bonded and arranged differently
Diamond is a 3D network of strong covalent bonds; graphite is stacked sheets held together only by weak forces, so layers slide off.
3. Some old cathedral windows are thicker at the bottom. Is this because glass is a liquid that slowly flows downward?
- Yes, glass flows a few millimeters per century
- No, the panes were made uneven
- Yes, but only in warm climates
Show the answer
Answer: No, the panes were made uneven
Room-temperature glass would need far longer than the age of the universe to sag visibly; old panes were simply uneven and often installed thick side down.
The whole quiz comes before your apps
BrainTok asks a few questions like these before the apps you choose open, so your screen time turns into learning. For iPhone.
Join the beta