1. Silicon vs. Carbon Different atoms?

2. Hypothesis We believe that silicon and carbon are made up of different atoms. The following information should help to prove our hypothesis. CarbonSilicon

3. FACTUAL EVIDENCE

4. General Properties Carbon Name: Carbon Symbol: C Atomic Number: 6 Elemental Category: Non-Metal Atomic Mass: appx.12 amu Electron Configuration: 1s 2 2s 2 2p 2 Allotropes: There are 12 known allotropes of carbon (diamond, graphite, etc.) Carbon is the basic component of life and is found in almost everything (fats, proteins, sugar, DNA, etc) Silicon Name: Silicon Symbol: Si Atomic Number: 14 Elemental Category: Metalloid Atomic Mass: appx. 28 amu Electron Configuration: 1s 2 2s 2 2p 6 3s 2 3p 2 Allotropes: There are 2 main allotropes (crystalline silicon and amorphous silicon). There is also a possibility of two more allotropes (Polycrystalline and microcrystalline silicon) *An allotrope is a variant of a substance consisting of only one type of atom (element). It is a new molecular configuration, with new physical properties.*

5. Atomic Properties Carbon Proton Number: 6 Neutron Number: 6 Electron Number: 6 Oxidation States: 2, +4 Crystal Structure: hexagonal (graphite) tetrahedral (diamond) tetrahedral (diamond) unpredictable (coal) unpredictable (coal) Electronegativity: 2.55 (pauling scale) Atomic Radius: 70 pm (picometres) Isotopes: Has 15 known isotopes – the three naturally occurring are: 12 C, 13 C and 14 C. Orbits: Highest orbital level is p. Has no d orbit. Silicon Proton Number: 14 Neutron Number: 28 Electron Number: 14 Oxidation States: 4 Crystal Structure: diamond Electronegativity: 1.90 (pauling scale) Atomic Radius: 111 pm (picometres) Isotopes: Has numerous isotopes ranging from 22 Si to 44 Si. ranging from 22 Si to 44 Si. Orbits: Highest orbit level is d. *Electronegativity describes the ability of an atom to attract electrons towards itself in a covalent bond. An atom's electronegativity is affected by both its atomic weight and the distance that its valence electrons are from the nucleus. The higher the electronegativity number, the more an element or compound attracts electrons towards it.* *The atomic radius of an element is a measure of the size of its atoms, usually the distance from the nucleus to the boundary of the surrounding cloud of electrons.*

6. Chemical Properties Carbon Bonds: Forms strong, stable bonds with itself and other elements. Reacts with air: yes, oxidizes to form carbon dioxide (CO 2 ) [with heat] Reacts with Hydrogen: yes, reduces to methane. Can create Hydrocarbons: yes Silicon Carbon is a connecting block in “Organic Chemistry,” the chemistry of life (also the chemistry required to produce fuels, solvents, plastics, dies, pharmaceuticals,etc.). Carbon can create four covalent bonds allowing it to link to itself in order to create carbon chains of different lengths/ configurations, or to connect to non-carbon atoms in order to form compounds with unique and specialized chemical properties. Bonds: Forms weaker bonds. Reacts with air: yes, reacts to form silcon dioxide (SiO 2 ) [with heat] Reacts with Hydrogen: No Can create Hydrocarbons: No Silicon reacts vigorously with halogens to form silicon tetrahalides especially fluorine since it takes place at room temperature but the others requiring warming over 300°C. Silicon does not react with most acids under normal conditions but is dissolved by hydrofluoric acid, HF. Silicon is attacked by bases such as aqueous sodium hydroxide to give silicates, which are highly complex chemicals containing the anion [SiO 4 ] 4-

7. Physical Properties Carbon Electrical Conductivity: 0.07 * 10 6 S cm -1 Electrical Resistance: 3.5 * 10 -5 Ω Density: Ranging from 2.267 g/cm 3 (graphite) to 3.515 g/cm 3 (diamond) Phases: Has no liquid phase, only a solid and a gas phase. Sublimation Point: 3642 ºC Flammability Class: Combustible solid (graphite) Thermal Conductivity: 1.29 W/cmK Silicon Electrical Conductivity: 1.2 * 10 -5 S cm -1 Electrical Resistance: 6.40 * 10 2 Ω Density: 2.57 g/cm 3 Phases: Has a liquid phase along with a gas and solid phase as well. Boiling Point: 2355 ºC Flammability Class: Combustible solid in powdered form. Thermal Conductivity: 1.48 W/cmk *Ω is an ohm, a unit used in the international system of measurements to measure resistance. * *W stands for watts which is a unit of power that measures rate of energy conversion.* *K stands for Kelvin which is a unit of temperature and is one of the seven SI base units.*

8. PHYSICAL EVIDENCE *Please be patient for slow videos*

9. Physical Properties Carbon (1 st substance shown in video) - Usually black in colour however clear and colourless when in diamond form. - Usually black in colour however clear and colourless when in diamond form. - Lacks luster - Lacks luster Silicon (2 nd substance shown in video) - Silver and black in colour. - Lustrous Colour

10. Mechanical Properties CarbonSilicon Hardness A fingernail, with a hardness of 2.5 mohs, was able to scratch the carbon, however not very well. Therefore this allotrope of carbon most likely has a hardness of less than 2.5 mohs. A knife, with a hardness of 5.5 mohs was unable to scratch the silicon. Therefore silicon has a hardness over 5.5 mohs. Silicon has a hardness of 7 mohs. Carbon has varied hardness levels. It can vary from 0.5 mohs (graphite) to 10.0 mohs (diamond.

11. Explanation - Chemical and physical properties of matter depend on the electron cloud surrounding the atoms. - Therefore they also depend on the number of protons in the nucleus. - Basically the chemical and physical properties are based on the atomic number. - Silicon and carbon also have different electron configurations, which means the electron clouds are different. - Since carbon and silicon have so many physical, chemical and mechanical differences, it is easy to say that these two elements are made of different atoms. Not to mention that they have two different atomic numbers (which means they have different amounts of subatomic particles – different, or differently arranged, atoms.)