What are the rules for drawing Lewis diagrams for molecules?
Just to retire this question....
When given a chemical formula, we can quickly determine how many valence electrons are needed to form chemical bonds by consulting the Periodic Table. We then use VESPER to determine the geometry. In the case of organic compounds, this is relatively simple because carbon has four covalent bonds to a first approximation, nitrogen three, and oxygen two.
You can find some guidance here, but in order to determine your understanding level, you should really be reading your text and reviewing previous exam papers.
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The rules for drawing Lewis diagrams for molecules are:
- Count the total number of valence electrons in the molecule.
- Determine the central atom and arrange the outer atoms around it.
- Connect the central atom to the outer atoms with single bonds.
- Distribute the remaining electrons as lone pairs on the outer atoms to satisfy the octet rule.
- If there are remaining electrons after satisfying the octet rule for all atoms, place them on the central atom as lone pairs.
- If the central atom does not have an octet, form multiple bonds (double or triple) with outer atoms to achieve octet fulfillment.
- Ensure that each atom in the molecule has a stable electron configuration (a complete octet for most elements or a duet for hydrogen and helium).
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When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
- How do dipoles cancel out?
- The noble gas xenon forms several compounds (usually involving oxygen or fluorine), but neon, which is also a noble gas, doesn't form compounds. Why? Why couldn't Ne form NeF4 in a similar way to XeF4?
- What are induced dipole-dipole forces?
- How many single bonds are formed by boron?
- For ethane, what is the correct framework of the Lewis structure?

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