The atomic number of lithium is 3. how many neutrons does an atom of lithium have if it is represented by the symbol shown below?

7li

6. using 3 – 4 sentences explain (in your own words) why water expands when it freezes? 7. using your knowledge of colligative properties explain whether sodium chloride or calcium chloride would be a more effective substance to melt the ice on a slick sidewalk. use 3 – 4 sentences in your explanation.