Answer:
Modern periodic law
Explanation:
There are many ways of stating the modern periodic law. Generally, the modern periodic law states that the properties of elements are a periodic function of their atomic numbers. That means, similar properties recur periodically when elements are arranged according to increasing atomic number.
Two scientists were largely responsible for our present day understanding of the modern periodic law, they are, Mendeleev and Moseley. Their work laid the foundation for the periodic table in its current form.
About 1.051 moles (depends on how u round it)
Answer:
d. Radon-222
Explanation:
²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂He
Alpha particle is a helium nucleus with mass number 4 and atomic number 2. According to the law of conversation of mass, the sum of the mass number and atomic number must be equal on both side of the reaction.
Since the mass number of Ra is 226 and that of He is 4. The mass number of the unknown element must be 226 - 4 = 222.
Since the atomic number of Ra is 88 and that of He is 2. The atomic number of the unknown element must be 88 - 2 = 86.
Now looking in the periodic table Radon is the only element with atomic number 86.
