Periodic table is the representation of elements in an order
The history of periodic table can be summarized as
a) 1829 : Johann Dobereiner proposed the triad rule. According to him we can classify the elements in a triad where the atomic mass of middle element is average of atomic mass of the near by two atoms.
For example : Li, Na and K is a triad. Where atomic mass of Na is average of atomic mass of K
atomic mass of Na = 7+ 39 / 2 = 23
However, with the further discovery of elements the law was rejected.
b) 1864 : John Newland proposed the law of octave. According to him we can arrange the elements in a set of seven elements where the property of second set of seven elements will resemble the properties of first of seven elements or property will be repeated after seven elements. This was also rejected due to its limited applicability.
c) Meyer : He arranged some 28 elements into six different families based on their atomic masses. The members of each familiy shared some common properties.
d) 1869 : Mendleev : He actually developed a periodic table based on atomic mass of elements. He arranged the elements into groups and periods. He even left space for some undiscovered elements, which were later on discovered.
e) 1916 : Henry Moseley : He finally arranged elements based on their atomic number based on X-ray studies. He proposed the modern periodic law that the periodic properties of elements are due to atomic number of elements.
Answer:
1,144 grams
Explanation:
Mass = Density * Volume
220mL * 5.2 g/mL = 1,144 grams
Hmm. This is very unspecific but it could either be indicating the pH of the solution or just saying it is an aqeous solution.
Answer:
It can:
1. make more pollution
2. release more greenhouse gases
3. affect the Earth
4. melts icebergs
5. animals lose home in Antarctica.
This difference in environments inside and outside of cells is important, and living organisms need to maintainthese cellular barriers for growth, reproduction, and homeostasis, which is the ability to maintain stable, constant internal conditions.