[adaumus]

Just wondering if you count the lone pairs only on the central atom of a molecule, or do you count all lone pairs. I just started a chemistry class and have confused myself. Also wondering if O2 is considered to not have a central atom? Thanks.

adaumus

[chenbeier]

Each Oxygen in O₂ has 2 lone pairs.

[adaumus]

Thanks. Yeah, I'm just wondering on something like BeCl2, if you count the 6 lone pairs on the 2 Chlorine atoms, or do you consider the compound to have 0 lone pairs because the central atom Beryllium doesn't have any. I'm confused.

[chenbeier]

You have to check any atom, each chlorine has 3 and Beryllium 0 lone pair. To count lone pair for a molecule make no sense.

[adaumus]

Thanks. I'm trying to answer a school question of e.g. "how many lone pairs does BeCl2 have?" I don't know whether to say 0 (since central atom doesn't have a lone pair) or 6 (since the 2 Chlorine atoms have 3 each) as the answer. I don't know what protocol is. Adam

[adaumus]

or e.g. BF3, the 3 fluorine molecules have 9 lone pairs, and Boron has 0 lone pairs. I don't know the correct way to answer "how many lone pairs does BF3 have?" Do I go off of what the central atom has, or look at the whole compound molecule to answer. Cheers, Adam

[chenbeier]

If they asking for the molecule then you have to count all of them. No choice then. But again each atom has some or no lone pairs. Normally it should be asked how many lines or has Be in BeCl₂.
If in the protocol there is no multiple choice answer, then I would write in words how I described it.