Si Atomic Mass

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This is a list of chemical elements, sorted by atomic mass (or most stable isotope) and color coded according to type of element. Each element's atomic number, name, element symbol, and group and period numbers on the periodic table are given. The number in parenthesis gives the uncertainty in the 'concise notation' dis given in parenthesis next to the least significant digits to which it. Multiply the amu by the percentage of occurrence to arrive at an average atomic mass of 28.0891 We take the amu of each isotope, multiply it by the percentage of occurrence, and end up with a weighted average: 27.9769xx.92xx.04xx.0312 (quick note - there is a bit of rounding in here - the abundance percentages add up to 1.01, so the number we calculate is going to be.

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The mass is one of the fundamental metric in the International System of Units, that is measured in kilograms (kg). The gram (g) is equal to 1⁄1000 of a kilogram(or 1E-3kg). Other units are used in SI:tonne (t), electronvolt (eV), and the atomic mass unit (u). In addition, a variety of different mass units are used outside the SI system, such as the slug (sl), the pound (lb), the Planck mass (mP), and the solar mass. In normal situations, the weight of an object is proportional to its mass, which usually makes it unproblematic to use the same unit for both concepts.

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Element Silicon - Si

Comprehensive data on the chemical element Silicon is provided on this page; including scores of properties, element names in many languages, most known nuclides of Silicon. Common chemical compounds are also provided for many elements. In addition technical terms are linked to their definitions and the menu contains links to related articles that are a great aid in one's studies.


Silicon Menu

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Overview of Silicon

  • Atomic Number: 14
  • Group: 14
  • Period: 3
  • Series: Metalloids (Nonmetal)

Silicon's Name in Other Languages

  • Latin: Silicium
  • Czech: Křemík
  • Croatian: Silicij
  • French: Silicium
  • German: Silizium - r
  • Italian: Silicio
  • Norwegian: Silisium
  • Portuguese: Silício
  • Russian: Кремний
  • Spanish: Silicio
  • Swedish: Kisel

Atomic Structure of Silicon

  • Atomic Radius: 1.46Å
  • Atomic Volume: 12.1cm3/mol
  • Covalent Radius: 1.11Å
  • Cross Section (Thermal Neutron Capture) σa/barns: 0.171
  • Crystal Structure: Cubic face centered
  • Electron Configuration:
    1s2 2s2p6 3s2p2
  • Electrons per Energy Level: 2,8,4
    Shell Model
  • Ionic Radius: 0.4Å
  • Filling Orbital: 3p2
  • Number of Electrons (with no charge): 14
  • Number of Neutrons (most common/stable nuclide): 14
  • Number of Protons: 14
  • Oxidation States: 4
  • Valence Electrons: 3s2p2
    Electron Dot Model

Chemical Properties of Silicon

  • Electrochemical Equivalent: 0.26197g/amp-hr
  • Electron Work Function: 4.52eV
  • Electronegativity: 1.9 (Pauling); 1.74 (Allrod Rochow)
  • Heat of Fusion: 50.55kJ/mol
  • Incompatibilities:
    Chlorine, fluorine, oxidizers, calcium, cesium carbide, alkaline carbonates
  • Ionization Potential
    • First: 8.151
    • Second: 16.345
    • Third: 33.492
  • Valence Electron Potential (-eV): 144

Physical Properties of Silicon

  • Atomic Mass Average: 28.0855
  • Boiling Point: 2628K 2355°C 4271°F
  • Coefficient of lineal thermal expansion/K-1: 4.2E-6
  • Conductivity
    Electrical: 2.52E-12 106/cm Ω
    Thermal: 1.48 W/cmk
  • Density: 2.33g/cc @ 300K
  • Description:
    Hard dark gray non-metal.
  • Elastic Modulus:
    • Bulk: 100/GPa
    • Youngs: 47/GPa
  • Enthalpy of Atomization: 439.3 kJ/mole @ 25°C
  • Enthalpy of Fusion: 46.44 kJ/mole
  • Enthalpy of Vaporization: 439 kJ/mole
  • Flammablity Class: Combustible Solid in powder form
  • Freezing Point:see melting point
  • Hardness Scale
    • Mohs: 6.5
  • Heat of Vaporization: 384.22kJ/mol
  • Melting Point: 1683K 1410°C 2570°F
  • Molar Volume: 12.05 cm3/mole
  • Optical Reflectivity: 28%
  • Physical State (at 20°C & 1atm): Solid
  • Specific Heat: 0.71J/gK
  • Vapor Pressure = [email protected]°C

Regulatory / Health

  • CAS Number
    • 7440-21-3 amorphous powder
  • UN/NA ID and ERG Guide Number
    • 1346 / 170 amorphous powder
  • RTECS: VW0400000
  • OSHAPermissible Exposure Limit (PEL)
    • TWA: 15 mg/m3 total particulate
      5 mg/m3 respirable particulate
  • OSHA PEL Vacated 1989
    • TWA: 10 mg/m3 total particulate
      5 mg/m3 respirable particulate
  • NIOSHRecommended Exposure Limit (REL)
    • TWA: 10 mg/m3 total particulate
      5 mg/m3 respirable particulate
  • Routes of Exposure: Inhalation; Ingestion; Skin and/or eye contact
  • Target Organs: Eyes, skin, respiratory system
  • Levels In Humans:
    Note: this data represents naturally occuring levels of elements in the typical human, it DOES NOT represent recommended daily allowances.
    • Blood/mg dm-3: 3.9
    • Bone/p.p.m: 17
    • Liver/p.p.m: 12-120
    • Muscle/p.p.m: 100-200
    • Daily Dietary Intake: 18-1200 mg
    • Total Mass In Avg. 70kg human: 1 g

Who / Where / When / How

  • Discoverer: Jöns J. Berzelius
  • Discovery Location: Stockholm Sweden
  • Discovery Year: 1824
  • Name Origin:
    Latin: silex (flint).
  • Abundance of Silicon:
    • Earth's Crust/p.p.m.: 277100
    • Seawater/p.p.m.:
      • Atlantic Suface: 0.03
      • Atlantic Deep: 0.82
      • Pacific Surface: 0.03
      • Pacific Deep: 4.09
    • Atmosphere/p.p.m.: N/A
    • Sun (Relative to H=1E12): 4.47E+07
  • Sources of Silicon:
    Silicon is the second most abundant element and comprises 25% of the earth's crust. Makes up major portion of clay, granite, quartz (SiO2), and sand. Approximate annual world production wide production: electronics grade pure silicon, 5000 tons; metallurgical grade, 480,000 tons; ferrosilicon, 3,400,000. Primary mining areas are Austria, Italy, India, South Africa, Australia, Canada, USA, Brazil.
  • Uses of Silicon:
    Used in glass as silicon dioxide (SiO2). It is used as a semiconductor to make microchips for electronics (like your computer). Silicon is also used in solar cells, tools, cement, grease and oils.
  • Additional Notes:
    Silicon carbide (SiC) is one of the hardest substances known.

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A list of reference sources used to compile the data provided on our periodic table of elements can be found on the main periodic table page.

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How To Calculate Atomic Weight

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