ZnS Structure & Characteristics (15 Important Facts)

ZnS is the chemical formula of zinc sulfide and it can form two types of structures i.e. zinc blend and wurtzite. Let us discuss some more brief details on the ZnS structure.

ZnS can show polymorphism and has a zinc blend structure means it shows a framework like a diamond and by applying different temperatures to ZnS it can convert to Wurtzite and show hexagonal molecular symmetry. The zinc blend is thermally stable shows cubic structure and is also known as Sphalerite.

ZnS is an ionic compound and has Zn2+ and S2- ions. In this structure both Zn2+ and S2- are in 1:1 stoichiometry. It shows a tetrahedral arrangement of Zn2+ and S2- ions in both forms. Let us have some more detailed discussion on the lone pairs, valence electrons, formal charge, and various characteristics of ZnS structure and some facts about it.

How to draw ZnS structure?

ZnS (zinc sulfide) shows its unique nature by forming two different crystal structures. Both the Zinc blend and Wurtzite structures of ZnS have some common features mentioned below.

  • They both have a stoichiometry of 1:1 in ZnS i.e. 1 Zn2+: 1 S2-.
  • They both have coordination number 4 i.e. 4:4 coordination Zn2+ and S2- ions.
  • As per the radius ratio rule, the large size S2- ions can occupy the corners of the unit cell and smaller size Zn2+ is present in the voids of the unit cell.
  • Thus each S2- ion is surrounded by 4 Zn2+ ions and each Zn2+ ion is surrounded by 4 S2- ions.
  • They both have tetrahedral geometry or coordination or arrangement.
  • In any crystal structure if there are ‘n’ number of particles, then it has tetrahedral voids 2’n’ and octahedral void is ‘n’.

Zinc Blend or Sphalerite:

  • The zinc blend structure of ZnS shows a face center cubic (FCC) structure or a cubic closed packed (CCP) structure. (AB type structure)
  • Thus, as we have 4 S2- ions in FCC structure, so we have 8 tetrahedral voids and 4 octahedral voids.
  • In FCC structure there is a tetrahedral void is present on every corner of the cube.
  • Each S2- ion is present on the four corners and faces of the cubic structure. Therefore S2- = (1 / 8 S2- x 8 corners) + ( 1 / 2 S2- x 6 faces) = 1 + 3 = 4 S2-.
  • Each Zn2+ ion is present in the alternate or opposite tetrahedral voids of the cubic structure. Therefore, Zn2+ = (1 / 2 Zn2+ x 8 T. V) = 4 Zn2+
ZnS ( Zinc Blend ) structure

Wurtzite (ZnS):

  • The wurtzite structure of ZnS shows a hexagonal closed packing (HCP) structure.
  • It can form alternate layers of Zn2+ and S2- ions in an HCP structure. It has the 1st layer of 6 S2- anions, 2nd layer of 3 Zn2+ cations, 3rd layer of 3 S2- anion, and 4th layer of 6 Zn2+ cations.
  • In wurtzite, the Zn2+  cations reside in the octahedral sites or voids.
  • Thus it forms the ABAB type HCP structure of wurtzite.
ZnS ( Wurtzite ) structure

ZnS structure valence electrons

The outermost electrons of an atom or molecules which are ready to donate or accepted by another atom are called valence electrons. Take a look at ZnS valence electrons.

The ZnS structure has a total of 8 valence electrons. It has 2 elements i.e. zinc and sulfur. It is a combination of metal and non-metal and is an ionic compound. The Zn has 2 valence electrons as it is in the 12th group. The S atom has 6 valence electrons as it is in the 16th group of the periodic table.

The calculation for ZnS valence electrons is explained in the details steps given below.

  • Valence electrons on Zinc atom is = 02 x 01 (Zn) = 02
  • Valence electrons on Sulphur atom is = 06 x 01 (S) = 6
  • Total valence electrons on ZnS structure = 2 (Zn) + 6 (S) = 8
  • The total electrons pair on ZnS structure is identified by dividing its valence electrons by 2 = 8 / 2 = 4
  • Therefore, the ZnS structure has a total of 8 valence electrons and 4 electron pairs.

ZnS structure lone pairs

Unshared pairs of electrons present on the atoms of a molecule are called lone pair electrons. Let us have a brief discussion on the ZnS lone pair electrons.

The ZnS structure has a total of 8 lone pair electrons. It has a total of 8 valence electrons. The Zn atom donates its 2 valence electrons to the S atom and the S atom accepts 2 electrons from the Zn atom. Thus it is an ionic compound being a cation and anion due to positive and negative charges on it.

The calculative part of ZnS structure lone pair electrons is explained in the following steps below.

  • Lone pair electrons on ZnS is = Valence electrons of ZnS (V. E) – Number of bonds / 2
  • Zn atom has lone pair electrons is = 0 (V. E) – 0 (bonds) / 2 = 0
  • S atom has lone pair electrons is = 8 (V. E) – 0 (bonds) / 2 = 8
  • Thus, the lone pair of electrons present in the ZnS structure is 8.

ZnS structure shape

The sequential atomic close – packed arrangement in the molecule or a compound is called molecular shape. Let us discuss some brief about the ZnS structure shape.

The ZnS compound shows linear, tetrahedral, and, octahedral shapes. The shape of ZnS depends on its number of Zn2+ and S2- ions and its structure (ZnnSn). The basic Zn – S structure shows its linear shape as it is diatomic and contains only two atoms connected to each other.

The FCC structure is tetrahedral in sphelarite and HCP structure is octahedral in wurtzite.

ZnS structure hybridization

The mixing and recasting of the orbitals of atoms to form a new hybrid orbital with the same energy is called hybridization. Below we are discussing ZnS structure hybridization.

The ZnS structure shows s, sp3, and sp3d2 hybridizations in Sphelarite and wurtzite structures. It cannot show any definite hybridization as it has complex crystal structures and a huge network of atoms. If ZnS shows linear geometry then it has ‘s’ hybridization.

If ZnS shows tetrahedral geometry then it has ‘sp3’ hybridization. If ZnS shows octahedral geometry then it shows ‘sp3d2’ hybridization. The hybridization of ZnS depends on its number of ions and the formation of its geometry. Atomic orbitals of Zn and S get mixed with each other to form new hybrid orbitals of the same energy.

ZnS structure angle

The angle within any two alternated bonds behind the central atoms in a molecule is called the bond angle. Take a look at a more brief discussion of the ZnS bond angle.

The ZnS structure can show 1800, 109.50, or 900 bond angles as per its geometry. The ZnS can show various structures, various geometry, and hybridization of its Zn and S atoms. Thus, if ZnS has a linear shape of 1800, a tetrahedral shape then 109.50, the octahedral geometry then it has a 900 bond angle.

Is ZnS solid or gas?

The compounds having specific fixing of their atoms in a closed manner and are hard in nature are solid compounds. Let us see whether ZnS is a solid or a gaseous compound.

The ZnS compound is solid in nature. ZnS is an ionic substance and its Zn2+ and S2- ions are linked with ionic bonds but both the ions get overlap their orbitals to form new hybrid orbitals.  It shows slight covalent character too to being solid. It is a white or yellow color solid crystalline compound.

Is ZnS soluble in water?

Water solubility depends on the tendency of the solute which gets dissolved in the water solution. Take a brief look at the discussion of whether ZnS is soluble in water or not.

The ZnS is insoluble in water. It has more density than water solution. It has more lattice energy than hydration energy. Thus, ZnS cannot be completely dissociated into the water to form hydrogen bonds with negative parts of water molecules. But it can react with water if the temperature is applied to it.

Why ZnS is insoluble in water?

ZnS is water insoluble because of its complex closed – packed array of Zn2+ and S2- ions. Thus the bonds of ZnS cannot depart to get soluble in water. On adding ZnS to water and applying external heat or temperature to the ZnS – H2O solution.

 It gets reacts with water thus forming a hydrogen bond and producing zinc hydroxide (Zn(OH)2) and liberating hydrogen sulfide (H2S) gas. The ZnS and water solution reaction is given below.

ZnS + 2 H2O → Zn(OH)2 + H2S

Is ZnS polar or nonpolar?

The polar or non-polar molecule gets determined due to the electronegativity difference between its atoms. Let us see whether the ZnS molecule is polar or non – polar.

The ZnS is polar in nature. It is an ionic compound and has 2 opposite charges on it showing that it is polar. The S atom is more electronegative than zinc metal and has an electronegativity difference of 0.98. This value is recommended for polar compounds by Pauling’s rule confirms ZnS is polar.

It has unequal electron distribution on both Zn and S atoms due to its electronegativity difference. The electron density in ZnS is pulled by the S atom towards itself. Thus, it develops net dipoles on it and has a positive charge on the Zn atom and a negative charge on the S atom.

Is ZnS acid or base?

The species which can donate protons are acids and the species which can accept protons are bases. Below we are discussing briefly whether ZnS is an acid or a base.

ZnS is a non – acidic or non – basic compound. It is a naturally occurring salt. It can be more stable when it is in an aqueous solution at acidic pH and reacts with the acid to form salts. It is also stable in alkaline pH with a more negative pH value.

ZnS get oxidized in an acidic solution to form zinc sulfate and oxidation with an alkaline solution produces zinc hydroxide.

Is ZnS electrolyte?

The compounds which get dissociate on adding to water and are able to conduct electricity are called electrolytes. Take a look at a brief discussion on ZnS as an electrolyte.

The ZnS can act as electrolytes. On adding ZnS to water it gets ionizes into Zn2+ cation and S2- anion. It is not easily dissolved in water due to high lattice energy. Thus apply external energy i.e. heat to make ZnS soluble in water. Only then it can form ions and conduct electricity and act as electrolytes.

Is ZnS salt?

The product formed due to reactions between acidic and basic compounds is called salts. Let us discuss more details on an explanation of whether ZnS is a salt or not.

ZnS is a salt because it contains metal and non–metal elements in it. It is produced by the reaction of Zn metal and S non–metal atoms. It forms an ionic compound due to a combination of Zn2+ and S2- ions. It is also formed due to a reaction between zinc oxide and hydrogen sulfide and acts as salt.

The reaction of the formation of ZnS as salt is given below.

Zn (s) + S (s) → ZnS (s)

Zn2+ + S2– → ZnS

ZnO + H2S → ZnS + H2O

Is ZnS ionic or covalent?

The atoms in a molecule are attached to the electrostatic force of attraction are ionic and if attached with sigma bonds are covalent. Let us see whether ZnS is ionic or covalent.

ZnS is an ionic compound. It is composed of oppositely charged cations and anions i.e. Zn2+ and S2- ions. Their ions get connected with each other due to the strong electrostatic force of attraction and form a strong ionic bond between them hence it shows ionic character and is not covalent.

Is ZnS phosphorescent?

Phosphorescence is a photoluminescence type, in which the species absorb light and emit it for a long period of time. Let us see in detail whether ZnS is phosphorescent or not.

ZnS compound is phosphorescent. It can show color change due to absorption of UV light on ZnS. The electrons of ZnS absorb light (stored) and get excited and jump from their lower energy state to a high energy state. Thus it gets emits light for a long period of time and acts as a phosphorescent.

Is ZnS fluorescence?

Fluorescence is photoluminescence, in which the species absorbs light and emits that light immediately. Below we are discussing brief details of ZnS fluorescence nature.

ZnS shows fluorescence. Pure ZnS cannot act as a fluorescence. It acts as fluorescence only if there are impurities like cadmium (Cd2+) and silver (Ag+) present in ZnS and interferes in a lattice of ZnS. Light like IR, UV, X-ray, etc. hits on the ZnS surface and absorbs photon energy by ZnS.

The electrons get promoted to a higher energy level corresponding with impurity atoms and came back to the ground energy level showing the emission of light suddenly without delay. Here, it also changes color from white to green.

Conclusion:

ZnS (zinc sulfide) has two structures i.e. Sphalerite and Wurtzite. Zn2+ ions occur in tetrahedral sites and octahedral sites in it. It has 8 valence electrons and 4 lone pairs. It shows linear, tetrahedral, and octahedral shapes. It has a face – centered cubic and hexagonal closed pack structure. It is water – insoluble, polar, solid salt, electrolyte, phosphorescent, and fluorescence.

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