What does applied chemistry have to do with making ice cream?

Well you have to mix chemicals which caused a chemical reaction. When you mix salt and ice the freezing point of liquid changes. the ice gets colder

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.