Chapter 7 Flashcards
Abundance and Properties of Carbon
- vital component for living systems
- 11th most abundant metal
- has three isotopes; 12C(98.9% abundant), 13C(1.1% abundant) and 14C (traces)
- one of the highest melting points of any element.
- can under pho sublimation changing from a solid state directly to a gas at temperatures above 3500°C
- non metal but a number of forms can conduct electricity
- can form single, double and triple covalent bonds with several other elements
- can form large molecules and lattice structures by bonding to itself
Define Sublimation
Sublimation is the process by which a substance goes directly from the solid phase to the gaseous phase, without passing through a liquid phase.
What is an allotrope
An allotrope is a different form of the same element in which the atoms combine in different ways.
Allotropes form when elements exits with their atoms in serve all different structural arrangements giving them different physical properties.
Atoms are bonded to each other in different, specific ways, giving them significantly different properties from other allotropes of the same element.
What is an amorphous
An amorphous is a structure that has no consistent arrangement of particles.
Example of an allotrope other than Carbon
Oxygen
O2
- oxygen gas consist of diatomic molecules with the formula O2
- each oxygen atom in this arrangement is bound to one other oxygen atom
O3
- ozone is another molecule containing only oxygen
- it has the formula O3
- consist of a central oxygen atom bound to two other oxygen atoms
Both only contain oxygen atoms, they are both allotropes of oxygen
What are allotropes of Carbon
- Diamond
- Graphite
- Amorphous Carbon
- Graphene
- Fullerenes
Explain the Allotrope DIAMOND
- hardest naturally occurring substance known
- sublimes
- non-conductive
- brittle
- high melting points or decomposition temperatures
- atoms are held firmly in fixed positions in the lattice
A diamond is made up of carbon atoms that bond with four neighbouring carbon atoms forming a covalent network lattice. This structure makes diamond extremely hard.
- When an atom has four electron pairs in its outer shell, the electron pairs position themselves in a TETRAHEDRAL SHAPE
- form single covalent bonds to other four carbon atoms in a tetrahedral arrangement
- does not contain small, discrete (individual) molecules (like water- Eg H2O)
Uses
- jewellery, cutting tools ams drills
What is a Covalent Network Lattice
An arrangement of atoms in a lattice in which there are strong covalent bonds between the atoms in all three dimensions
Covalent Layer lattice
An arrangement of atoms in a lattice in which there are strong covalent bonds between the atoms in all three dimensions.
What is a Diamond
A form of pure carbon that is the hardest naturally occurring substance
Explain the properties of diamond via its structure
- has Single Covalent bonds between carbon atoms are strong bonds. The entire structure of a diamond consist of a continuous network of these bonds, making diamond very HARD and RIGID
- There are no small particles in diamond, so there are no weak forces between the atoms. There are only strong covalent bonds between the carbon atoms and this makes the sublimation point very high (3500°C)
- The rigidity means that diamonds are brittle and break rather than bend.
- Diamond does not conduct electricity because it does not contain any change particles that are free to move.
- Since the atoms in diamonds are held together very strongly, the thermal conductivity is extremely high. It is five times greater than that of copper, leading to some speciality electronic uses where diamond is used to transfer heat away from some important electrical components
What is silica?
Silicon, silicon carbide and silicon dioxide (silica) are most common substance in earth.
Is a covalent network lattice substance like Diamond.
* forms this lattice as it has 4 valence electrons, making it possible for the atoms to join continuously to themselves or other atoms such as Oxygen and Carbon
- Silicon dioxide forms a covalent network lattice in which each silicon atom is bonded tetrahedrally to four oxygen atoms and each oxygen atom is bonded to two silicon atoms.
- can be found as quartz and sand (major component of glass)
What is a amorphous Carbon
It is irregular structure of carbon atoms; many varieties exits with many different, non-continuous packing arrangements
Properties
- conductive
- non- crystalline
- cheap
Uses
- printing ink
- Carbon black filler
- activated charcoal
- photocopying
Explain Graphite
- in graphite each carbon atom is covalently bonded to three other carbon atoms. The layered network structure contains delocalised electrons. Bonds within the layers are strong but bonds between layers are weak dispersion forces.
Graphite is a different form of carbon
- carbon atoms in graphite are in layers
- there are strong covalent bonds between the carbon atoms in each layer
- there are weak forces called dis prison forces between layers
- one delocalised electron per carbon atom
- the structure of graphite is referred to as COVALENT LAYER LATTICE
The properties of Graphite due to structure
- Strong Covalent Bonds between the atoms in each layer explain graphite’s resistance to heat. Graphite sublimes at 3600°C
- Each Carbon atom is bonded to three other carbon atoms. The fourth valence electron from each atom is able to move with the layer. The electrical conductivity of graphite is due to these delocalised electrons.
- makes it suitable for applications such as battery electrodes where conductivity is required but a metal is not suitable.
- is also a lubricant due to the weak Dispersion forces between layers allows these layers to slide over each other and to reduce the friction between moving parts. *such as locks and machinery
- used as an additive to improve the properties of rubber products and it can be woven into a fibre, which can be used to make strong composite materials such as those used in Tennis Rackets, fishing rods and racing car shells.
