IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: $!$RatJumper$!$ on November 10, 2010, 07:13:29 pm
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In the physics CIE syllabus for A levels, it says under Phases of Matter:
"distinguish between the structure of crystalline and non-crystalline solids with particular reference to metals, polymers and amorphous materials."
What do we need to know in specific for that? I don't have any notes on this so am pretty lost.
Thankx
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In the physics CIE syllabus for A levels, it says under Phases of Matter:
"distinguish between the structure of crystalline and non-crystalline solids with particular reference to metals, polymers and amorphous materials."
What do we need to know in specific for that? I don't have any notes on this so am pretty lost.
Thankx
Hmm........there are not much notes on that. It also enters the part of elasticity. Anyway here are my notes on the particular subject and which you need to know. ;)
Crystalline solids
Pure metals are generally crystalline in structure. The atoms are arranged in a regular manner forming a three-dimensional lattice structure. With such ordered packing system, the largest number of atoms can be arranged within the smallest possible volume. The potential energy of the system tends to a minimum for stability.
Crystalline solids have a very high Young's Modulus. They elongate and undergo plastic deformation under action of large forces.
Example : Copper.
Amorphous solids
These are solids obtained when a molten material is rapidly solidified and such that the disordered liquid structure is retained, However, in an amorphous solid, we have short-range ordering.
Amorphous solid have a very high Young's Modulus and generally they obey Hooke's law upto the breaking point.
Example : glass.
Polymers
They consist of long chains of carbon atoms bonded to hydrogen or other atoms.
They have a very low Young's Modulus and they tolerate large strains while exhibiting elastic behaviour.
Example : Rubber
The second paragraph in the 3 descriptions are most important. ;)
Hope it helps :)
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Hmm........there are not much notes on that. It also enters the part of elasticity. Anyway here are my notes on the particular subject and which you need to know. ;)
Crystalline solids
Pure metals are generally crystalline in structure. The atoms are arranged in a regular manner forming a three-dimensional lattice structure. With such ordered packing system, the largest number of atoms can be arranged within the smallest possible volume. The potential energy of the system tends to a minimum for stability.
Crystalline solids have a very high Young's Modulus. They elongate and undergo plastic deformation under action of large forces.
Example : Copper.
Amorphous solids
These are solids obtained when a molten material is rapidly solidified and such that the disordered liquid structure is retained, However, in an amorphous solid, we have short-range ordering.
Amorphous solid have a very high Young's Modulus and generally they obey Hooke's law upto the breaking point.
Example : glass.
Polymers
They consist of long chains of carbon atoms bonded to hydrogen or other atoms.
They have a very low Young's Modulus and they tolerate large strains while exhibiting elastic behaviour.
Example : Rubber
The second paragraph in the 3 descriptions are most important. ;)
Hope it helps :)
Thank you so much! :)
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Thank you so much! :)
Anytime dude :)
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Can you give me the right definitions of "SPONTANEOUS" and "RANDOM" in context to radioactive decay?
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Can you give me the right definitions of "SPONTANEOUS" and "RANDOM" in context to radioactive decay?
Here you are. ;)
Spontaneous decay refers to the fact that the decay cannot be induced, nuclei disintegrate on their own. The decay being continuous and rate of decay being independent of physical factors such as temperature.
Random decay indicates that the decay is probabilistic having a constant probability of decay per unit time. We cannot predict which nucleus will disintegrate and each disintegration being independent of other disintegrations.