What is the conceptual understanding of a nucleophilic attack?
A nucleophilic attack is best understood as a species with available electrons reacting with a species of positive charge or low electron density. For example, ammonia can react with a carbonyl carbon because nitrogen's lone pair of electrons attacks the partially positive carbon atom. This carbon atom has a partial positive charge because its electron density is shifted towards the oxygen atom double-bonded to it.
What is the appropriate method for graphically subtracting two vectors (a - b)?
Using the "tip-to-tail" method, we will combine the arrow end of vector a to vector b. Since this is subtraction, we must reverse the direction of vector b before attaching. Finally, we draw a resultant vector from the origin of vector a to the arrow end of our reversed vector b.
How does increased calcium ion intake at the synapse of neurons impact the ability to release neurotransmitters?
Calcium ion intake acts as a messenger in the neuron, causing vesicles containing neurotransmitters to fuse with the cell membrane and release neurotransmitters into the synaptic cleft.