Answer:
- <em>He realized that some elements had not been discovered.</em>
Explanation:
Some scientists that tried to arrange the list of elements known before Mendeleev include Antoine Lavoisier, Johann Döbereiner, Alexandre Béguyer de Chancourtois, John Newlands, and Julius Lothar Meyer.
<em>Dimitri Mendeleev</em> was so succesful that he is recognized as the most important in such work.
Mendeleev by writing the properties of the elements on cards elaborated by him, and "playing" trying to order them, realized that, some properties regularly (periodically) repeated.
The elements were sorted in increasing atomic weight (which is not the actual order in the periodic table), but when an element did not meet the pattern discovered, he moved it to a position were its properties fitted.
The amazing creativity of Mendeleev led him to leave blanks for what he thought were places that should be occupied by elements yet undiscovered. More amazing is that he was able to predict the properties of some of those elements.
When years after some of the elements were discovered, the genius of Mendeleev was proven because the "new" elements had the properties predicted by him.
Answer:
Energy was released
Explanation:
Decrease in temperature means less energy, but the energy had to have been transferred because energy can't be destroyed or created. So if the temp. went down, energy must have been lost. (If it had been absorbed, the temp. would have gone up)
Answer:
3
Explanation:
the three elements involved in this compound are Li, S, O.
lithium, sulfur, and oxygen. Which create the ionic compound, "Lithium Sulfate."
7 atoms total, since there are two lithium, four oxygen, and one sulfate atom. this is a white inorganic salt.
I think the answer is number (4)
The answer is 9.03 × 10²⁴<span> molecules.
</span><span>Avogadro's number is the number of units (atoms, molecules) in 1 mole of substance.
Make the proportion.
</span><span>6.02 × 10²³ molecules per 1 mol
</span>x per 15 mol
6.02 × 10²³ molecules : 1 mol = x : 15 mol
x = 6.02 × 10²³ molecules * 15 mol * 1 mol
x = 90.3 × 10²³ molecules
x = 9.03 × 10 × 10²³ molecules
x = 9.03 × 10²³⁺¹ molecules
x = 9.03 × 10²⁴ molecules
