Hydrogen Sulfide (H2S) Lewis Structure
Lewis structure of Hydrogen sulfide (H2S) contains two S-H single bonds around sulfur atom. Also, there are two lone pairs around sulfur atom. Concept of number of total valence electrons of sulfur and hydrogen atoms are used to draw lewis structure of H2S. Each step of drawing lewis structure of H2S is explained in detail in this tutorial.
H2S lewis structure
Lewis structure of H2S is similar to the lewis structure of H2O. There are two S-H bonds and two lone pairs around sulfur atom in H2S lewis structure.
Steps of drawing lewis structure of H2S
There are several steps to draw the lewis structure of H2S. Those steps are explained in detail in this tutorial. Because H2S molecule is a simple molecule, some of these steps are not used. In such cases, they are mentioned with those respective steps.
- Find total number of electrons of the valance shells of hydrogen atoms and sulfur atom
- Total electrons pairs as lone pairs and bonds
- Center atom selection
- Mark lone pairs on atoms
- Mark charges on atoms if there are charges.
- Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain best lewis structure.
Important: Drawing correct lewis structure is important to draw resonance structures correctly.
Total number of electrons of the valance shells of H2S
There are two elements; hydrogen and sulfur. Hydrogen is a group IA element and has only one electron in its last shell (valence shell). Sulfur is a group VIA element in the periodic table and contains six electrons in its last shell. Now we know how many electrons are includes in valence shells of hydrogen and sulfur atom.
- valence electrons given by hydrogen atoms = 1 * 2 = 2
- valence electrons given by sulfur atom = 6*1 = 6
- Total valence electrons = 2 + 6 = 8
Total valence electrons pairs
Total valance electrons pairs = σ bonds + π bonds + lone pairs at valence shells
Total electron pairs are determined by dividing the number total valence electrons by two. For, H2S, Total pairs of electrons are 4 in their valence shells.
Center atom of H2S molecule
To be the center atom, ability of having greater valance is important. Then, from hydrogen and sulfur, which atom has the highest valence? Maximum valence of sulfur is six. hydrogen's only valence is one. Therefore, sulfur atom should be the center atom of H2S. Now, we can construct the sketch of H2S to show how atoms are located in the molecule.
Lone pairs on atoms
After deciding the center atom and sketch of H2S molecule, we can start to mark lone pairs on atoms. Remember that, there are total of four electron pairs.
- There are already two S-H bonds in the above drawn sketch. Now only two (4-2) electron pairs are remaining to mark on atoms.
- Usually, those remaining electron pairs should be started to mark on outside atoms. But in H2S, hydrogen atom are the outside atoms which cannot keep more than two electron in its last shell. There are already two electrons in hydrogen atoms. Therefore, we cannot mark those two electrons pairs on hydrogen atoms.
- Therefore, then mark those two electrons pairs on center atom; sulfur atom.
Mark charges on atoms
There are no charges on sulfur atom and hydrogen atoms. Also, remember that H2S is a molecule which does not have a charge.
Check the stability and minimize charges on atoms by converting lone pairs to bonds
Because there is no charges on atoms, no need to reduce charges as a step of obtaining the best lewis structure. Already, we have got the best lewis structure for H2S.
Questions
How many lone pairs on sulfur atom in H2S?
There are two lone pairs on sulfur atom in H2S lewis structure. Also, there are eight electrons around sulfur atom in H2S. In some lewis structures such as H2SO4, you can see sulfur can keep more than eight electrons in its valence shell.
how many valence electrons are in H2S
There are eight valence electrons are in H2S. From eight, six electrons are given by sulfur and each hydrogen atom gives one electron.