Answer:
Ok I will help you in your chemistry
Explanation: The atomic mass of iron (Fe) is 55.85 amu. The atomic mass of radium (Ra) is 226 amu. One mole of atoms of any element contains 6.022 X 1023 atoms, regardless of the type of element. The mass of one mole of an element depends on what that element is, and is equal to the atom mass of that element in grams.
Aufbau principle:
Electrons are added one at a time from the lowest energy orbitals available until all the orbitals are filled.
According to the Aufbau principle, electrons fill lower energy orbitals first.
(i) Boron (Z = 5)
Electronic configuration =
(ii) Neon (Z = 10)
Electronic configuration =
(iii) Aluminium (Z = 13)
Electronic configuration =
(iv) Chlorine (Z = 17)
Electronic configuration =
(v) Calcium (Z = 20)
Electronic configuration =
[Image]
Answer:
230
Th
90
Explanation:
The left side shows the element uranium with mass number 234 (superscript to the left of ths symbol) and atomic mass 92 (subscript to the left of the symbol).
So, you have to find the mass number and atomic numbers missing on the right side which added to those shown for the helium atom reach 234 and 92.
This the the mathematics:
1) Mass number of U - mass number of He = 234 - 4 = 230 ⇒ the mass number of the missing element is 230.
2) atomic number of U - atomic number of He = 92 - 2 = 90 ⇒ the atomic number of the missing element is 90.
Now, you use the atomic mass to identify the element. You do it by simply searching in a periodic table. There you find that the atomic number 90 corresponds to thorium, whose symbol is Th.
Now you have that the product that completes the right side of the decay equation is:
230
Th
90
