Identify by group number two groups on the periodic table that are very reactive, and state the numbers of valence electrons the elements in each group have.

In 2002, the rare earth elements mine in mountain pass, california was closed because

The atomic number, or number, is the described as the number of in the nucleus of an chemical element.

Which of the following statements is true about energy quantization at the atomic level? electrons in the outermost orbits are the most stable. electrons in all the orbits around the nucleus have the same amount of energy. electrons in the orbit closest to the nucleus have the least amount of energy. electrons absorb or release the same amount of energy independent of the energy levels.