If you don't know all the answers just answer the ones you do know and number them so I know which one you are answering 1.which of the following characteristics was NOT included in Dmitri Mendeleev's periodic table A.heavier elements placed in rows closer to the bottom of the table B.Elements arranged by increasing atomic mass C. Elements placed in columns based on chemical properties or D. Distribution of elements determined by electron configuration 2. According to the periodic law what is the relationship between elements and periods A.element properties repeat from period to period B.Elements in a period have the same physical properties C. Elements have the same physical and chemical properties in any period or D. Elements in a period have the same chemical properties 3. Which of these sets of elements has similar properties consult the periodic table A.Strontium, magnesium, calcium, beryllium B. Oxygen, nitrogen, carbon C. Hydrogen, helium, neon or D. Chromium, magnesium, iron, cobalt
2. is D. 3. is B, because those 3 elements are in the same period.