Answer:
The average atomic mass is closer to Si- 28 because this isotope is present in more percentage in the sample.
Explanation:
Given data:
Atomic mass of silicon= ?
Percent abundance of Si-28 = 92.21%
Atomic mass of Si-28 = 27.98 amu
Percent abundance of Si-29 = 4.70%
Atomic mass of Si-29 = 28.98 amu
Percent abundance of Si-30 = 3.09%
Atomic mass of Si-30 = 29.97 amu
Solution:
Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)+(abundance of 2nd isotope × its atomic mass) / 100
Average atomic mass = (92.21×27.98)+(4.70×28.98)+(3.09×29.97) /100
Average atomic mass = 2580.04 +136.21+92.61 / 100
Average atomic mass = 2808.86 / 100
Average atomic mass = 28.08amu.
The average atomic mass is closer to Si- 28 because this isotope is present in more percentage in the sample.
B - Atomic number. Dmitri Mendeleev organised the table according to atomic weight, however this caused problems with elements such as iodine and tellurium, Iodine has a higher mass, but a lower atomic number. And to make iodine in the same group as similar elements (halogens), Mendeleev had to break his own rules and put it before tellurium in the table. Moseley fixed this problem by ordering the elements according to atomic (proton) number.
Answer: 6
Explanation:
1) The structure shown is:
3CH₃CH₂O
2) The molecule is CH₃CH₂O. The chemical formula is CH₃CH₂O. The subscripts indicate the number of atoms of the corresponding atom in each molecule.
Then, there are 1 + 1 = 2 atoms of C, 3+ 2 = 5 atoms of H, and 1 atom of O.
3) The number in front of the molecule is the coefficient. It is 3, and it tells the number of molecules.
So, there are 3 molecules, which means that you have 3 times a many atoms as calculated previously.
That is 3×2 = 6 atoms of C, 3 × 5 = 15 atoms of H, and 3 × 1 = 3 atoms of O.
Then, the number of atoms of carbon (C) in 3 molecules is 6
Oxygen had 6 valence electrons
Scirnce uses a method of testing to declare rules or facts. myth and fairy tales have no way of being tested. cats are a physical creature we can see, test, and observe. a mythical idea canny be tested. for example: mermaids cannot be tested as we have none to observe.
