Example: Sulfur Trioxide
Chemical formula: SO3
Valence e-: ?
Needed e-: ?
Difference/Bond: ??
Please help me!
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To find the valence electrons in an atom or molecule, you first need to determine the electron configuration. In the case of sulfur (S), its atomic number is 16, so its electron configuration is as follows: 1s2 2s2 2p6 3s2 3p4. The valence electrons are the outermost electrons, which in this case would be the electrons in the 3s and 3p orbitals. Thus, sulfur has 6 valence electrons.
For oxygen (O), its atomic number is 8, and its electron configuration is 1s2 2s2 2p4. The valence electrons in this case are in the 2s and 2p orbitals, giving oxygen 6 valence electrons as well.
Since there are three oxygen atoms in sulfur trioxide (SO3), we need to add up the valence electrons of each atom. Sulfur contributes 6 valence electrons, and each oxygen contributes 6 valence electrons. So the total number of valence electrons in SO3 is 6 + (3 × 6) = 24.
To determine the number of electrons needed to achieve a stable, full valence shell for each atom, you can refer to the octet rule. Generally, atoms tend to gain, lose, or share electrons to achieve a stable configuration with 8 valence electrons (except for the first period nonmetals, which only require 2 valence electrons).
Both sulfur and oxygen need 2 more electrons to achieve their respective stable configurations. So the total number of electrons needed in SO3 is 2 + (3 × 2) = 8.
The difference or bond can be calculated by subtracting the number of valence electrons from the number of needed electrons. In this case, it would be 8 - 24 = -16. The negative sign indicates that there is an excess of electrons.
Hope this helps clarify the concept for you!