Answer: Elements in Group 2
Explanation: The periodic table was arranged by Dmitri Mendeleev specifically around similarites in their chemical behaviors. He found that as atomic number increases, at some point an element starts to react in a manner similar to a previous one. When that happened, he would place the larger element under the smaller one, and eventually noticed a periodicity in the table. Elements in a column (Groups) had similiar chemical properties. We know today that these similarities are due to the electron configuration, and that these configurations repeat themselves. He left gaps in the table when he could find an existing element with properties similar to others in that group. I big leap of faith, but it worked. Elements for those missing boxes were eventually discovered.
Answer:
The correct answer is A
Explanation:
That water stops moving once it gets to the dam and turns into potential energy
Answer:
The nucleus consists of 25 protons (red) and 30 neutrons (blue). 25 electrons (green) bind to the nucleus, successively occupying available electron shells (rings). Manganese is a transition metal in group 7, period 4, and the d-block of the periodic table. It has a melting point of 1246 degrees Celsius.