I think its A because some scientist from the Department of Physics of Northeastern University found out that is not a part of Dalton's atomic theory.
The periodic table is one of the most important tools in the history of chemistry. It describes the atomic properties of every known chemical element in a concise format, including the atomic number, atomic mass and relationships between the elements. Elements with similar chemical properties are arranged in columns in the periodic table.
The table thus is a quick reference as to what elements may behave the same chemically or which may have similar weights or atomic structures.
Hope this answer helps you
Answer:
1s2 2s2 2p6 3s2 3p6
Explanation:
Calcium is the 20th element. It has 20 electrons in it's neutral state. The electronic configuration is given as;
1s2 2s2 2p6 3s2 3p6 4s2
However in the compound; calcium chloride, it does not exist in it's neutral state.
CaCl2 --> Ca2+ + Cl-
In Ca2+ state, it has lost two electrons, The total number of electrons becomes; 20 - 2 = 18 electrons.
The electronic configuration is given as;
1s2 2s2 2p6 3s2 3p6
