Silicon Chemical Properties (25 Facts You Should Know)

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Silicon is the most abundant electropositive element in the earth’s crust. Though silicon is a metalloid, it shows metallic luster. Let us look at some Silicon facts in detail.

Silicon usually occurs in combined form as silicon dioxide which is commonly called as silica. Silicon compound has non-metallic qualities  which combines with oxygen, phosphorous, nitrogen and other elements and it also forms alloys in the molten state.

Chemical properties like melting point, boiling point, electronegativity, ionisation and others would be discussed for Silicon throughout this article. 

Silicon symbol

The symbol of Silicon is Si. The first two letters of the full name is easily picked up for using as its symbol, which differently expose the element.

Silicon group in periodic table

Silicon is a group 14 element in the same periodic group as carbon, but chemically behaves distinctly from all of its group counterparts.

Silicon period in periodic table

Silicon is placed at period 3 in the periodic table and all elements of period 3 has three shells.

Silicon block in periodic table

Silicon belongs to p-block. The p-orbital can hold up to six electrons.

Silicon atomic number

The atomic number of Si is 14. It means it has 14 protons, 14 electrons and 14 neutrons.

Silicon atomic Weight

The atomic mass of Si is 28.0855 u. Therefore its atomic weight is 28.0855 u*9.8 m/s2 = 275.2379 um/s2.

Silicon Electronegativity according to Pauling

According to Pauling scale, electronegativity of Si is 1.9, which is very low. Rather it has tendency to give up electrons.

Silicon atomic Density

The atomic density of Si is 2.33 Mg/m3.

Silicon melting point

The melting point of Si is 1,410 °C (1,683.15 K).

Silicon boiling point

The boiling point of Si is 2,355 °C (2,628.15 K).

Silicon Van der Waals radius

Van der Waals radius of Si is 210 pm. It means the radius of hard sphere of one Si atom is 210 pm.

Silicon ionic radius

Ionic radius (rion) of Si4+ is 0.41 Å. The anionic radius of an isoelectronic species will be always greater than the cationic radius. Therefore, Si4+ will have a lower ionic radius.

Silicon isotopes

Isotopes are the different forms of one single atom. These differ from each other by the total number of nuclei. Let us find the isotopes of Si in the table below.

IsotopeDecay
abundancehalf-life(t1/2)modeproduct
28Si92.2%stable
29Si4.7%stable
30Si3.1%stable
31Sitrace2.62 hβ–31p
32Sitrace153 yβ–32p
Main isotopes of silicon (14Si)

Silicon electronic shell

Electronic shells are those pathways around which electrons are hold in an atomic structure. Let us count the number of electronic shells and electrons on it in an atom of Si.

Silicon atom has three electronic shells. The outermost shell has n=3. Thus, there are 4 valence electrons. Two are in the 3s subshell and other two are in the 3p subshell.

Silicon energy of first ionisation

The first ionisation energy of Si atom is 786.5 k Jmol-1.

X ????X+ +e–

Silicon energy of second ionisation

The second ionisation energy of Si is 1577.1 k Jmol-1.

X+ ???? X2+ +e–

Silicon energy of third ionisation

The third ionisation energy of Si is 3231.6 kJ mol-1.

X2+ ???? X3+ +e–

Silicon oxidation states

The oxidation number of Si is +4.

Silicon electron configurations

The electronic configuration of Si can be condensed as [Ne] 3s² 3p2. The full notation of configuration in accordance with Aufbau principle is 1s2 2s2 2p6 3s2 3p2.

Silicon CAS number

The CAS number of Si for verification of the element is 7440-21-3.

Silicon ChemSpider ID

The ChemSpider ID of Si is 13148729. With the help of this number, anyone can search chemical facts of Si in ChemSpider database.

Silicon allotropic forms

Allotropes are those forms of an element, which are similar by properties but different as per the structures. Let us count and identify the allotropic forms of Si here.

There are two allotropic forms of Si at room temperature: Amorphous and Crystalline.  Amorphous Si takes the form of a brown powder whereas Crystalline Si has a metallic luster and a greyish color.

image 1 4
Allotropic forms of silicon

Silicon chemical classification

Silicon is classified as a metalloid and is a solid at room temperature. Since some of its properties are similar to metals and nonmetals.

Silicon state at room temperature

Silicon is solid at room temperature.

Is Silicon paramagnetic?

Paramagnetic elements refer to those periodic elements, which possess free or unpaired electrons. Let us find if Si behaves as a paramagnetic element or not. 

Silicon is paramagnetic because there are 3 2p orbitals where each one can occupy 2. Since orbitals of the same energy must be singly filled, there will be 2 unpaired electrons in the 2p orbital of Si. These electrons are weakly attracted by an external magnetic field .Hence Si is paramagnetic element. 

Conclusion

This article has identified several chemical facts regarding the presence of Si in the periodic table. Si has been found quite similar as carbon as Si has an extensive organic chemistry, given the ability to form 4 bonds to carbon, hydrogen, nitrogen.