What is surface tension ​

Surface tension is,  the surface where the water meets the air, water molecules cling even more tightly to each other.

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.