Spin Quantum Number: This is one of the four quantum numbers. It describes the spin direction (up or down) of an electron - kind of like whether our student prefers to sit upright or slouch!
Hund's Rule: This rule states that every orbital in a subshell is singly occupied before any orbital is doubly occupied. It's like ensuring every desk in a classroom has one student before any desk gets two students.
Quantum Mechanical Model: This model describes the behavior of electrons in atoms. It's like the school handbook that outlines how students should behave and where they should be at certain times.