[vivekfan]

When you use the arrow pushing notation for a reaction, are plus signs needed for reactants and products? And what's the difference between a reactant above an arrow and its normal placement?

[sjb]

Do you mean plus signs as meaning charged intermediates, or just two or more reactants? Typically reactants above arrows are catalysts, in my experience, or this style is used to place more emphasis on one reactant over another.

[vivekfan]

Do you mean plus signs as meaning charged intermediates, or just two or more reactants? Typically reactants above arrows are catalysts, in my experience, or this style is used to place more emphasis on one reactant over another.

I mean plus signs as two or more reactants. Like in the dehalogenation reaction, there's the alkyl halide but then it said a base is added to it, and put the base above the arrow instead of as a reactant...what does this mean?

Also are the plus signs (that are used to indicate more than one reactant) needed in arrow pushing?

[azmanam]

This is similar to the other question you asked.  The answer is it doesn't matter.  It's the preference of the person writing the rxn.  Sometimes reactants are before the arrow,  sometimes above, sometimes even below if there are a lot of reagents in a complex reaction.  I wouldn't get too concerned over where each part of the reaction is written.  It changes from person to person and there are no over-arching guidelines.

[vivekfan]

This is similar to the other question you asked.  The answer is it doesn't matter.  It's the preference of the person writing the rxn.  Sometimes reactants are before the arrow,  sometimes above, sometimes even below if there are a lot of reagents in a complex reaction.  I wouldn't get too concerned over where each part of the reaction is written.  It changes from person to person and there are no over-arching guidelines.

Thanks for all your help. What about in the arrow pushing notation...would you just show electrons without any plus signs between reactants or products?

[azmanam]

What about in the arrow pushing notation...would you just show electrons without any plus signs between reactants or products?

by convention, we don't normally show the + sign.  If you did, everyone would still know what you were talking about.  Just make sure it's clear it's a plus sign... don't put the + sign too close to an atom that it looks like a positive charge.