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Other names/abbreviations:

Si

Element no:	14
Element group:	14 (IUPAC) IV A (American labelling) IV B (European labelling)
Element type:	Nonmetals
CAS-Number:	7440-21-3
EINECS-Number:	231-130-8

Quantitative analysis

Method 4500-Si G Inductively Coupled Plasma Method [1]. A portion of the sample is digested in a combination of acids. The digest is aspirated into an 8,000 K argon plasma where resulting light emission is quantified for 30 elements simultaneously.

Method limit of detection in water = 0.05 mg/L

Safety

Symbol: -
R-phrases: -
S-phrases: -

Physical properties

Appearance
	Physical state @ 20°C:	Solid [4]
	Color:	Amorphous silicon: Brown Crystalline silicon: Grey Greyish-Black [4]
	Odor:	Odourless [4]

Bulk properties
	Molecular weight (g/mol):	28.0855(3) [1]
	Melting point (°C):	1420 [1]
	Boiling point (°C):	3280 (Approximately) [1]
	Density (g/cm3):	2.336 (alpha form) [1] 2.905 (beta form) [1]
	Elastic properties: Young's modulus (GPa): Rigidity modulus (GPa): Bulk modulus (GPa):	113 [3] 39.7 [3] 98.7 [3]

Thermodynamic properties
	ΔfH°gas (kJ/mol):	450.0 (monoatomic) [3] 594.0 (Si2) [3]
	ΔfH°solid (kJ/mol):	0.0 (monoatomic) [3]
	ΔH°fusion (kJ/mol):	50.6 [1] 50.21 [3]
	ΔH°vaporization (kJ/mol):	383 [1]
	S°gas (J/K·mol):	168.0 (monoatomic) [3] 229.9 (Si2) [3]
	S°solid (J/K·mol):	18.8 (monoatomic) [3]
	ΔfG°gas (kJ/mol):	405.5 (monoatomic) [3] 536.0 (Si2) [3]
	Cp (gas) (J/K·mol):	22.3 (monoatomic, 25 °C) [3] 34.4 (Si2) [3]
	Cp (solid) (J/K·mol):	19.789 (monoatomic, 25 °C) [3]

Crystal structure
	Crystal type:	DC [3]

Electronic properties
	Electron configuration:	1s2-2s2-2p6-3s2-3p2
	Ionic radius (Å):	Si(IV): 0.40 [1]

Conductivity
	Electrical resisitvity (μΩ·cm):	4.8·10-5 (approximately) [1]

References

1: Standard Methods for the Analysis of Water and Wastewater, APHA, 1992, 18th edition

2: Greenwood,N.N., Earnshaw,A. Chemistry of the elements
2nd edition (1997) Edited by Greenwood,N.N., Earnshaw,A. pp. 1-1340, Butterworth-Heinemann. Oxford. Great Britain

3: Buch,A. Pure Metals Properties. A Scientific-Technical Handbook
1st edition (1999) Edited by Buch,A. pp. 1-306, ASM International and Freund Publishing House Ltd. Ohio. USA

4: Merck. ChemDAT The Merck Chemical Database Ver. 1.1.5

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© Michael Pilgaard
Created: October 6, 2008
Last update: October 9, 2008