Answer:
In chemical bonding: Arrangement of the elements. The horizontal rows of the periodic table are called periods. Each period corresponds to the successive occupation of the orbitals in a valence shell of the atom, with the long periods corresponding to the occupation of the orbitals of a d subshell.
Explanation:
The answer is 8 :)
All nobel gases have 8 outer electrons.
64: C
65: D because weathering is defined as rock being eroded/changed
hope i could help
add up the mass of protons and neutrons