* Scientists observed that elements have different properties, such as color, density, and reactivity.

Hypothesis:

* Mendeleev hypothesized that there was a relationship between the properties of elements and their atomic masses.

Experimentation:

* Mendeleev arranged the elements in a table according to their atomic masses and chemical properties. He organized known elements into families.

Data Analysis:

* Mendeleev noticed that elements with similar properties were grouped together in the periodic table.

Conclusion:

* Mendeleev's periodic table provided evidence to support his hypothesis that there was a relationship between the properties of elements and their atomic masses.

* Periodic Law stated that physical and chemical properties of elements were related predictable to properties of known elements their positions (in a table arrangement by properties) relative to other elements.

Further Research:

* Mendeleev's periodic table has been updated and expanded as new elements have been discovered, confirming and extend ing the periodic law.