As he began to teach inorganic chemistry, Mendeleev could not find a textbook that met his needs. Since he had already published a textbook on organic chemistry in 1861 that had been awarded the prestigious Demidov Prize, he set out to write another one. The result was Osnovy khimii (1868–71; The Principles of Chemistry), which became a classic, running through many editions and many translations. When Mendeleev began to compose the chapter on the halogen elements (chlorine and its analogs) at the end of the first volume, he compared the properties of this group of elements to those of the group of alkali metals such as sodium. Within these two groups of dissimilar elements, he discovered similarities in the progression of atomic weights, and he wondered if other groups of elements exhibited similar properties. After studying the alkaline earths, Mendeleev established that the order of atomic weights could be used not only to arrange the elements within each group but also to arrange the groups themselves. Thus, in his effort to make sense of the extensive knowledge that already existed of the chemical and physical properties of the chemical elements and their compounds, Mendeleev discovered the periodic law.
Is this a multiple choice? Anyways I will just give you a written answer and hopefully it helps.
A: Helium is made up of two electrons held by electromagnetic force to two protons that are inside of a nucleus along with one or two neutrons.
It was discovered in 1868.i hope this helps you .
The mass of nitric acid required to make the given solution is 0.0627 g.
The given parameters:
- <em>Volume of the acid, V = 250 mL</em>
- <em>pH of the acid, = 2.4</em>
The hydrogen ion (H⁺) concentration of the nitric acid is calculated as follows;
The molarity of the nitric acid is calculated as follows;
The number of moles of the nitric acid is calculated as follows;
The molar mass of nitric acid is calculated as;
The mass of the nitric acid contained in the calculated number of moles is calculated as;
Thus, the mass of nitric acid required to make the given solution is 0.0627 g.
Learn more about molarity of acids here: brainly.com/question/13864682
A decrease in the amount of gas in a container will mean a decrease in pressure.
