8 terms

Allotropes of Carbon

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Diamond
-giant covalent (macromolecular) structure
- each carbon is bonded to 4 others (sp3 hybridized)
-very high melting and boiling point, because energy must be supplied to break covalent bonds
- very hard
-does not conduct electricity, all electrons are held in covalent bonds and are not free to move
-not soluble in water or organic solvents because the forces between the atoms are too strong
Graphite
-giant covalent structure
-layered structure, each carbon is bonded to three others in a trigonal planar array (sp2 hybridized)
-Covalent bonds between the carbons, but London forces between the layers
-weak forces between the layers is an explanation for graphite as a good lubricant( used in pencils)
-very high melting and boiling point because covalent bonds within layers must be broken
-non soluble in water or non-polar solvents, due to covalent bonds
-conducts electricity because each carbon has extra electrons, delocalized system
Graphene
- a single layer of graphite
-very good electrical and thermal conductor
-high melting point
C60 Fullerene
-molecular structure, only London forces must be overcome when fullerene melts
-substantially lower boiling point than graphite and diamond
-hexagons and pentagons
-insoluble in water but soluble in some organic solvents, such as benzene
-does not conduct electricity
-sp2 hybridized
silicon dioxide
-SiO2
-Giant covalent structure
-each silicon bonded to four oxygen atoms, each oxygen is bonded to two silicon atoms
-basic shape is bent due to two lone pairs on the oxygen atom
-high melting and boiling points, covalent bonds
Graphite
Each C atom is sp2 hybridized covalently bonded to 3 others, forming hexagons in parallel layers with bond angles of 120. The layers are held only by weak van der waals forces so they can slide over each other
-contains only one non-bonded, delocalized electron per atom; conducts electricity due to the mobility of these electrons
-Non-lustrous, grey solid
- used as lubricant and in pencils
-giant macromolecular
Diamond
Each C atom is sp3 hybridized covalently bonded to 4 others tetrahedrally arranged in a regular repetitive pattern with bond angles of 109.5. It Is the hardest known natural substance.
-all electrons are bonded; non-conductor of electricity because there are no mobile electrons
-lustrous crystal
-polished for jewelry and machinery for grinding and cutting glass
-giant macromolecular
Fullerene C60
each C atom is sp2 hybridized, bonded in a sphere of 60 carbon atoms, consisting of 12 pentagons and 20 hexagons. Structure Is a closed spherical cage in which each carbon is bonded to 3 others.
-easily accepts electrons to form negative ions; a semiconductor at normal temp and pressure due to some electron mobility
-yellow crystalline solid, soluble In benzene
-Reacts with K to make superconducting crystalline material;related forms are used to make nanotubes for the electronics industry, catalysts and lubricants
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