Half-Lives In discussions of radioactivity, the  half-life  of an isotope refers to the time it takes for one-half of the sample to decay. If we start with 100 g of…

The Quantum Mechanical Model of the Atom Energy Is Quantized After Max Planck determined that energy is released and absorbed by atoms in certain fixed amounts kn…

Nuclear Reactions All of the processes discussed in this section are examples of  nuclear  reactions, which are different from ordinary chemical reactions. Ordinary…

Atomic Structure—What We Know Today Elements and Atoms An  atom  is the smallest particle of an element that retains the chemical properties of that element, and …

Valence Bond Theory Another topic that you’ll need to be familiar with for the SAT II Chemistry test is that of valence bond theory. By now, you are aware that two …