How did Mendeleeb come up woth the periodic table?

Mendeleev jotted down the symbols for the chemical elements, putting them in order according to their atomic weights and inventing the periodic table.

On 17 February 1869, Russian chemist Dmitri Mendeleev jotted down the symbols for the chemical elements, putting them in order according to their atomic weights and inventing the periodic table. So convinced was he of the soundness of his periodic law that he left gaps for these elements in his table.

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.