Summary
Summary Unit 22 Assignment A
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Pearson BTEC Level 3 National Extended Diploma in Applied Science Distinction Level
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Metals and Alloys:By allowing free electrons to move between the atoms, metals conduct electricity. There is
no atom or covalent bond tying these electrons to another substance. The vibration of one
free electron inside the lattice pushes those in the next atom because like charges repel one
another; the cycle then repeats. High thermal and electrical conductivity, ductility,
malleability, and high light reflectance are all qualities that define metals. Because metals
tend to combine with nonmetals more frequently than with one another, their atoms only
have about half of the full electron configuration in their outermost shell. The crystal
structure of these materials is what gives them their characteristics of hardness, stress
resistance, ductility, and malleability. Its tightly packed structure, which lacks a layer of
atoms, enables flexible deformation, and keeps it from being brittle. Metals and occasionally
non-metals are combined to form alloys. Alloys have atoms that are of varying sizes, which
makes it challenging for them to slide over one another. Because of this, alloys are more
durable than pure metals. The combination of a metal with a non-metal or with another
metal gives alloys their hardness and toughness. Due to the atomic layers in the structure
and chemical composition of each alloy and metal, metals and alloys are malleable and
ductile. Customising magnetizability is another advantage of utilising alloys. By configuring
the key components, this can be managed. You can manage magnetic induction thanks to
the alloying process.
Ceramics and Glass:
Glasses are a range of ceramic materials whose atomic structure defines them. Glass has a
disorganised amorphous structure rather than the crystalline structure that most other
ceramics exhibit. They vary from other crystalline ceramics because of this. Silicate glasses,
made from silica, are the most popular types of glasses. Every oxygen atom on a corner of a
tetrahedron in silica is shared with the tetrahedron next to it in a 3D network. Additionally,
sheets and chains of the silica tetrahedral unit are produced to create various ceramics.
Unlike glass, ceramics have a crystalline structure. Like NaCl and MgO, many ceramic
structures exhibit ionic bonding. Since the atoms are ions with opposite charges, they are
attracted to one another electrostatically. The ions arrange themselves in a predictable way.
The size of the ion charges and the size of the ions affect the ceramic's nature. Although
their modulus is typically higher than metals because of the bonding being stronger than
metallic bonding, ceramics and glasses have a distinct modulus like metals. The two hardiest
types of solids are ceramics and glassware. This is due to the localised bonding between
atoms making it challenging to move through the atomic lattice.
Polymers:
A material formed of macromolecules with repeating subunits is referred to as a polymer.
When the molecules of a simple chemical combine, the result is known as a polymer, and
the process of polymerization is what causes this to happen. Monomers are the substances
in which molecules combine to produce polymers. A chain of atoms makes up a polymer.
Covalent, van der Waals, and hydrogen bonding hold polymers together. Long chains of
covalent bonds indicate a strong intermolecular force. In comparison to many other organic
molecules, polymers have a higher melting point.
, The hardness, melting point, behaviour under heat, and flexibility are all impacted by
intermolecular forces. When compared to the intermolecular forces between small
molecules, the intermolecular forces in polymer molecules are much stronger. This
demonstrates that compared to substances containing smaller molecules, polymers melt at
a higher temperature.
A thermosetting plastic is a polymer that, when heated, permanently stiffens. A thermoset
or thermosetting polymer is another name for it. The reaction that increases the cross-
linking between polymer chains and cures the plastic is given energy by heat. By applying
more pressure or employing a catalyst, the rate of curing can be accelerated. Vulcanised
rubber, fibreglass, and epoxy resin are a few examples of typical thermosetting plastics. A
procedure known as polymerization is used to link monomers to create chains to create
thermoplastics. Thousands of monomers can be combined to create a single polymer chain.
Strong covalent bonds hold the atoms in a polymer chain together, whereas the forces
between chains are weak. To enhance functionality and physical and chemical qualities
before a thermoplastic may be utilised, it is blended with additives including stabilisers,
plasticizers, lubricants, flame retardants, and colourants. Thermoplastics have several
macroscopic properties, including being strong and hard but also flexible, lightweight, acid
and solvent resistant, and having a high melting and boiling temperature. Cross-linked,
amorphous polymers make up elastomers. They are flexible and elastic, which are
characteristics rubber shares. Stretching the long coiled, cross-linked materials is simple.
Viscoelasticity refers to the properties of elastomers, which are polymers with both viscosity
and elasticity. The molecules of elastomers typically exhibit a low Youngs modulus, high yield
strength, or high failure strain and are held together by a weak intermolecular force.
Carbon:
The four structures of carbon are fullerenes, graphite, graphene, and diamond. Every atom
in a diamond is connected to four other atoms, forming a massive covalent structure.
Diamond is extremely hard and has a high melting point due to its numerous strong covalent
connections. Diamonds don't conduct electricity since they don't have any free electrons.
Each carbon atom forms three covalent connections in graphite, which likewise has a
massive covalent structure. Carbon atoms form layers of hexagonal rings to form the
structure. Four electrons make up carbo's outer shell; three are bonded, leaving one free for
delocalization. Graphite is slippery, soft, and suited for use as a lubricant because the layers
in the structure allow it to slide over each other because there are weak intermolecular
forces holding them together. Graphite has a high melting point because it contains many
strong covalent bonds. Graphite's ability to conduct heat and electricity is also due to the
delocalized electrons. Strong covalent bonds between each bond make up the single layer of
graphite, known as graphene, which is one atom thick. The high melting and boiling points
are the primary characteristics. Because each carbon atom has a delocalized electron, it is
also a good electrical conductor.
Due to its strong covalent bond, graphene is the thinnest substance that is also the
strongest. It’s one atom thick layer makes it incredibly thin and transparent. Fullerenes are
hollow-shaped molecules consisting of carbon atoms. Fullerenes can contain rings of five or
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