Draw the Lewis structure for each of these molecules.
1. PH3
2. H2S
3. HCl
4. CCl4
5. SiH4
For H2S H• •S• •H H-.`S.`-H
Sure! To draw the Lewis structures for these molecules, you need to follow a few steps:
1. Determine the total number of valence electrons for each molecule. This can be done by referring to the periodic table. For molecules, you add up the valence electrons of each atom present.
2. Identify the central atom. This is usually the least electronegative element (the one that appears the farthest to the left on the periodic table) except for hydrogen.
3. Arrange the atoms around the central atom, forming single bonds between the central atom and other atoms.
4. Place any remaining electrons around the atoms to satisfy the octet rule (except for hydrogen, which only needs 2 electrons).
Let's go through each molecule one at a time:
1. PH3:
- Phosphorus (P) is the central atom.
- Phosphorus has 5 valence electrons, and each hydrogen (H) atom has 1 valence electron.
- Place the three hydrogen atoms (each with one bond) around the phosphorus atom.
- This uses a total of 3 electrons (1 electron for each hydrogen).
- Place the remaining 2 electrons around the phosphorus to give it a total of 8 electrons (octet rule).
- The Lewis structure for PH3 is:
H H
\ /
P
/
H
2. H2S:
- Sulfur (S) is the central atom.
- Sulfur has 6 valence electrons, and each hydrogen (H) atom has 1 valence electron.
- Place the two hydrogen atoms (each with one bond) around the sulfur atom.
- This uses a total of 2 electrons (1 electron for each hydrogen).
- Place the remaining 4 electrons around the sulfur to give it a total of 8 electrons (octet rule).
- The Lewis structure for H2S is:
H - S - H
3. HCl:
- Hydrogen (H) is the central atom since it appears before chlorine (Cl) on the periodic table.
- Hydrogen has 1 valence electron, and chlorine has 7 valence electrons.
- Place the chlorine atom (with one bond) connected to the hydrogen atom.
- This uses a total of 2 electrons (one from hydrogen and one from chlorine).
- The Lewis structure for HCl is:
H - Cl
4. CCl4:
- Carbon (C) is the central atom.
- Carbon has 4 valence electrons, and each chlorine (Cl) atom has 7 valence electrons.
- Place the four chlorine atoms (each with one bond) around the carbon atom.
- This uses a total of 4 electrons (one from each chlorine).
- Place the remaining 4 electrons around the carbon to give it a total of 8 electrons (octet rule).
- The Lewis structure for CCl4 is:
Cl
|
Cl - C - Cl
|
Cl
5. SiH4:
- Silicon (Si) is the central atom.
- Silicon has 4 valence electrons, and each hydrogen (H) atom has 1 valence electron.
- Place the four hydrogen atoms (each with one bond) around the silicon atom.
- This uses a total of 4 electrons (one from each hydrogen).
- Place the remaining 4 electrons around the silicon to give it a total of 8 electrons (octet rule).
- The Lewis structure for SiH4 is:
H H
| |
H - Si - H
| |
H H
Remember, Lewis structures are a simplified representation of molecules and their electron distribution. The sole purpose of this structure is to show the valence electrons and how they are shared between atoms in a molecule.