Position in the periodic table.
1. What is the difference between a period and a group on the periodic table of elements?
2. How does the number of valence electrons in sodium (Na) compare to the number of
valence electrons in calcium (Ca)?
A. Na has one more valence electron than Ca.
B. Na and Ca have an equal number of valence electrons.
C. Na has two fewer valence electrons than Ca.
D. Na has one fewer valence electron than Ca.
Bond Formation

Ithink its solid. hope this

Vander waals forces are inter molecular bonds that exist within molecules of the same substance. a water molecule is made up of oxygen and hydrogen atoms which share electrons between each other. the vander waals forces are forces that exist between multitude of different  molecules of water. dipole dipole forces is the type of vander waals force that exist in water. the oxygen atom which is more electronegative pulls the shared electron closer to itself thus generating a partial negative charge while the hydrogen acquire a partial positive charge. these two different charges causes attraction to occur in water molecules.