In what sequence do electrons fill the atomic orbitals within a sub level

Asingle atom of an element has 21 neutrons, 20 electrons, and 20 protons. which element is it? ok o z

The tendency of water molecules to stick together is referred to as a) adhesion b) polarity c) cohesion d) transpiration e) evaporation

13. a covalent bond between two atoms is likely to be polar if: a. one of the atoms is much more electronegative than the other. b. the two atoms are equally electronegative. c. the two atoms are of the same element. d. the bond is part of a tetrahedrally shaped molecule. e. one atom is an anion.