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.
The answer is B. light is reflected off the shirt
True
Explanation: Covalent bonds occur when electrons are shared between two atoms. A single covalent bond is when only one pair of electrons is shared between atoms.
Answer:
26,000 KL/kg will be the density of the Elephant.
<span>This problem is not about chemistry it is about math. the half-life of a certain thing is the time that it needs to decay 50% of what it had before. so if there is 4g, after 1 half there will be only 2g. so to become 1g it is passed 2 half-lives. 4,0g, 2,0g, 1,0g so it is the time divided by 2( numbers of half-lives). So the half-life of Francium 210 is 2,6 min.</span>
