Answer:
Energy levels
Explanation:
Elements in one row of the periodic table have the same energy levels. A row on the periodic table is the horizontal arrangement of elements. These rows are called periods.
There are 7 periods on the periodic table.
- Each elements on a period begins with an atom having one valence electrons and then ending with completely filled orbitals.
- Elements in the same period are known to have the same electronic shells which is the energy level.
- The principal quantum number of their electrons is the same.
Answer:
is the symbol for an oxide ion
Answer : Option C) Early modern era
Explanation : The historical era which was marked by the beginnings of European explorations, conquests of the Americas, trans-Atlantic slave trade and the rise of a globally intertwined economy was Early modern era. It was later followed by the medieval period.
<span>The addition of a catalyst to a chemical reaction provides an alternate pathway that c</span>atalysts lowers the activation energy.
