Chemistry of Carbon Compounds Properties of Carbon Allotropes Inorganic Compounds of Carbon Organic Chemistry
CARBON non-metallic element of group IV-A which constitutes only about 0.009 % by mass of Earth’s crust. (but it is the 6th most abundant element in the universe) exists in three isotopes: 12C, 13C, 14C has the unique ability to form long chains (consisting of more than 50 C atoms) and stable five or six-membered rings called catenation.
Some Physical Properties of Carbon Atomic number: 6 Electron Configuration: 1s22s22p2 Atomic mass: 12.0107 amu Melting Point: 3,823 K Boiling Point: 4,098 K Density: 2.2670 g/cm3 Phase (room temp.): solid
Allotropes two or more forms of the same element that differ significantly in chemical & physical properties.
Allotropes of Carbon Crystalline- have highly ordered 3D structure graphite diamond fullerenes Amorphous carbon black charcoal coke
Graphite graphite is derived from the Greek word “graphein” which means to write. It was named by the German Geologist Abraham Werner in 1789.
Properties & Uses of Graphite soft, greasy feel black mineral is made up of layers of carbon, the Carbon atoms arranged in rings of 6 atoms. layers slide easily over each other because of the weak inter-layer forces (Van der Waal’s forces) but inter atomic bonds are strong covalent bonds contains free electrons, which move along layers good conductor of heat & electricity used as pencil lead, lubricants, electrodes & raw material for making synthetic diamonds
Diamond transparent crystalline solid, with high density compared to other carbon allotropes hardest naturally occurring substance carbon atom is joined to 4 other Carbon atoms, forming a Tetrahedron, or 4 sided figure held together by covalent bonds used as cutting material, jewelries & for decorative purposes
Fullerenes a class of carbon molecules in which the carbon atoms are arranged into 12 pentagonal faces and 2 or more hexagonal faces to form a hollow sphere, cylinder, or similar figure. the most prominent of the fullerenes is buckminsterfullerene, a spheroidal molecule, resembling a soccer ball, consisting of 60 carbon atoms.
Fullerenes fullerene research is expected to lead to new materials, lubricants, coatings, catalysts, electro-optical devices, and medical applications. were first identified in 1985 by R. F. Curl, Jr., R. E. Smally, and H. W. Kroto (who shared the 1996 Nobel Prize in Chemistry)
STRUCTURE OF GRAPHITE
STRUCTURE OF DIAMOND
STRUCTURE OF BUCKMINSTERFULLERENE
Carbon Black formed when hydrocarbons such as methane are heated in a very limited supply of oxygen: CH4 + O2 C(s) + H2O used as pigment in black inks and making automobile tires
Charcoal formed when wood is heated strongly in the absence of air used in filters to remove offensive odors from air and colored or bad-tasting impurities form water
Coke impure form of carbon formed when coal (coal- a fuel substance of plant origin, largely or almost entirely composed of carbon with varying amounts of mineral matter) is heated strongly in the absence of air. used as a reducing agent in metallurgical process.
Inorganic Compounds of Carbon Oxides (carbon monoxide & carbon dioxide) Carbonates Bicarbonates Carbides Cyanides
Carbon Monoxide a colorless, odorless, toxic gas formed by the incomplete combustion of carbon-containing compounds. They are used for extracting nickels, organic synthesis and production of hydrocarbon fuels with hydrogen
Carbon Dioxide a colorless, odorless, non-toxic gas. it is an acidic oxide & used in beverages, fire extinguishers, manufacture of baking soda, NaHCO3, and soda ash, Na2CO3. CO2 can also exist in solid form, called “dry ice”, which is used as a refrigerant.
Carbonates are compounds containing the anion CO32- examples are calcium carbonate which can be found in egg shells, shells of marine organisms & in both limestone & marble
CaCO3(s) + H2CO3(aq) Ca2+(aq) + 2HCO3-(aq) Carbonates Calcium carbonate is normally water-insoluble. It will only dissolve in water saturated with CO2 because carbonated water (or carbonic acid) reacts with calcium carbonate to form calcium bicarbonate, which is water-soluble: CaCO3(s) + H2CO3(aq) Ca2+(aq) + 2HCO3-(aq)
Bicarbonates are compounds containing the anion HCO3- example is sodium bicarbonate or baking soda NaHCO3, a weak base added to recipes to neutralize the acidity of other ingredients. Baking soda is a mixture of baking soda and a weak acid, like tartaric acid, that when mixed with water, the acid reacts with the HCO3- ion to form CO2 gas, which causes the dough or batter to rise. HCO3-(aq) H+(aq) H2CO3(aq) H2O(l) + CO2(g)
Carbides ionic compounds formed from the combination of carbon & metals examples are CaC2 (“carburo”) and Be2C in which carbon is in the form of C22- or C4- ions which are strong Bronsted bases & reacts with water as: C22-(aq) + 2H2O(l) 2OH-(aq) + C2H2(g) C4-(aq) + 4H2O(l) 4OH-(aq) + CH4(g)
SiO2(s) + 3C(s) SiC(s) + 2CO(g) Carbides another example is the covalent compound of carbon with silicon called “carborundum” or silicon carbide, SiC. it is almost as hard as diamond & it has the diamond structure which can be prepared from the reaction: SiO2(s) + 3C(s) SiC(s) + 2CO(g)
Cyanides a carbon compound containing the anion group :CNN:- cyanide ions are extremely toxic used in the metallurgy of gold in the form of NaCN