To write the electron dot formulas (also known as Lewis structures) for selenium dichloride (SeCl2) and carbon diselenide (CSe2), we first need to understand the valence electrons of each atom involved.
SeCl2 (Selenium Dichloride)
Selenium (Se) is in Group 16 of the periodic table and has 6 valence electrons. Chlorine (Cl) is in Group 17 and has 7 valence electrons.
- Valence Electrons in Se: 6
- Valence Electrons in Cl: 7 (each Cl atom, and there are 2 Cl atoms: 7 x 2 = 14)
Total valence electrons for SeCl2 = 6 + 14 = 20 valence electrons.
Now, we arrange the electrons:
- Place Se in the center, surrounded by the two Cl atoms.
- Draw single bonds between Se and each Cl (each bond involves 2 electrons).
- This uses 4 electrons, leaving us with 16 electrons.
- Place 6 electrons (3 lone pairs) around each Cl atom to satisfy their octet.
- Now, we have used 4 (for bonds) + 12 (for 2 Cl lone pairs) = 16 electrons. This leaves 4 electrons for Se.
- Add 2 lone pairs around Se to complete its octet.
The final Lewis structure will look like this:
Cl:
..
|
:Se:
..
|
Cl:
..
CSe2 (Carbon Diselenide)
Carbon (C) is in Group 14 with 4 valence electrons, and selenium (Se) has 6 valence electrons. Since there are two Se atoms, we calculate:
- Valence Electrons in C: 4
- Valence Electrons in Se: 6 (each Se atom, and for 2 Se atoms: 6 x 2 = 12)
Total valence electrons for CSe2 = 4 + 12 = 16 valence electrons.
Organizing the electrons:
- Put C in the center, with two Se atoms on either side.
- Connect each Se to C with a single bond.
- This uses 4 electrons, leaving 12 electrons.
- Place 6 electrons (3 lone pairs) around each Se atom to complete their octets.
- Now, we have used 4 (for the bonds) + 12 (for 2 Se lone pairs) = 16 electrons.
The final Lewis structure will look like this:
:Se:
|
:C:
|
:Se:
In summary, the electron dot formulas for SeCl2 and CSe2 showcase the arrangement of valence electrons to fulfill the octet rule where possible.