In the first recrystallization, after the solid has been dissolved in warm acetone, the solution is allowed to cool slowly to room temperature. in an older procedure the warm solution was placed directly into an ice bath. how does this older procedure differ from a normal recrystallization and what might be the consequences

See explanation below.

Explanation:

In the older procedure, the solution is cooled so quickly that the recrystallization can be less effective. By allowing the solution to cool slowly, the maximum amount of crystal is formed, and also the impurities are trapped, so the process is more controlled than by the older one.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

a:

by the combination of an unlimited number of elements