The reason that some of the elements of period three and beyond are steady in spite of not sticking to the octet rule is due to the fact of possessing the tendency of forming large size, and a tendency of making more than four bonds. For example, sulfur, it belongs to period 3 and is big enough to hold six fluorine atoms as can be seen in the molecule SF₆, while the second period of an element like nitrogen may not be big to comprise 6 fluorine atoms.
The existence of unoccupied d orbitals are accessible for bonding for period 3 elements and beyond, the size plays a prime function than the tendency to produce more bonds. Hence, the suggestion of the second friend is correct.
Moles He = 7.83 x 10^24 / 6.02 x 10^23 =13.0
<span>mass He = 13.0 mol x 4.00 g/mol = 52.0 g</span>
the correct answer is A.
Each atom has three sub particles, which are electron, proton and neutron. To get the atomic mass for each atom, one has to add the masses of the proton, neutron and electron in an atom. For each atom, the major contributors to its mass are proton and neutron, this is because the mass of the electron is very small indeed. Thus, the atomic mass of an element is usually in the range of its mass number, which is obtained by the summation of proton and neutron. Since it is the number of proton that indicate an atomic number and it is the mass number that indicate atomic mass, therefore, atomic mass can be greater than the atomic number.
Answer:
0.0457 M
Explanation:
The reaction that takes place is:
- 2HBr + Ca(OH)₂ → CaBr₂ + 2H₂O
First we<u> calculate how many moles of acid reacted</u>, using the <em>HBr solution's concentration and volume</em>:
- Molarity = Moles / Volume
- Molarity * Volume = Moles
- 0.112 M * 12.4 mL = 1.389 mmol HBr
Now we <u>convert HBr moles to Ca(OH)₂ moles</u>, using the stoichiometric ratio:
- 1.389 mmol HBr *
= 0.6944 mmol Ca(OH)₂
Finally we <u>calculate the molarity of the Ca(OH)₂ solution</u>, using the <em>given volume and calculated moles</em>:
- 0.6944 mmol Ca(OH)₂ / 15.2 mL = 0.0457 M
