What was johann dobereiner’s contribution to the development of the periodic table ?
a. he arranged the elements according to increasing mass
b. he arranged the elements according to increasing atomic number
c. he identified triads of elements that had similar properties
d. he organized elements into four groups based on their properties

Which element in the third period would you expect to have the larger atomic radius, sodium (na) or sulfur (s)? a. sodium, because it has a higher effective nuclear charge attracting electrons in fewer energy levels. b. sodium, because it has fewer protons attracting electrons in the same energy levels. c. sulfur, because it has more protons attracting electrons in more energy levels. d. sulfur, because it has a higher effective nuclear charge attracting electrons in the same energy levels.

What mass of natural gas (ch4) must you burn to emit 276 kj of heat?

When water dissolves sugar, which process is not involved? o dissociation o hydration o surface area of the solute increases sa