In 1869 he published a table of the elements organized by increasing atomic mass.
Mendeleev is called the "father of the modern periodic table
stated that if the atomic weight of an element caused it to be placed in the wrong group, then the weight must be wrong. (He corrected the atomic masses of Be, In, and U)
was so confident in his table that he used it to predict the physical properties of three elements that were yet unknown.
After the discovery of these unknown elements between 1874 and 1885, and the fact that Mendeleev's predictions for Sc, Ga, and Ge were amazingly close to the actual values, his table was generally accepted.
However, in spite of Mendeleev's great achievement, problems arose when new elements were discovered and more accurate atomic weights determined.
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Answer:
the individual atom in the molecule
Explanation:
In chemistry, the ball-and-stick model is a molecular model of a chemical substance. Invidual spheres there represent atoms in the molecule. The bigger atomic number the atom has, the larger diameter of the spheres this atom has in this model.
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Answer:
2. Co(NO3)2 + H2
Explanation:
Hello,
In this case, we are evidencing a simple displacement reaction wherein the cobalt is able displace the hydrogen to produce cobalt (II) nitrate and gaseous hydrogen as a result of cobalt's higher activity:

Therefore, answer is 2. Co(NO3)2 + H2.
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