To allow for equations and problems in chemistry to be as precise as possible. When experiments are conducted, and even if the number is the slightest bit off, the problem or experiment could be impacted very negatively. It allows for complete accuracy to ensure nothing goes wrong, since chemistry is very touchy and risky when dealing with extremely unsafe elements.
Answer:
a. Sn or Si ⇒ Sn
b. Br or Ga ⇒ Ga
c. Sn or Bi ⇒ similar in size
d. Se or Sn ⇒ Sn
Explanation:
The larger atom has a larger atomic radius. We have to consider how varies the atomic radius for chemical elements in the Periodic Table. In a group (column), the atomic radius increases from top to bottom while in a period (file), it increases from right to left.
a. Sn or Si ⇒ Sn
They are in the <u>same group</u>. Sn is on the top, so it has a larger atomic radius.
b. Br or Ga ⇒ Ga
They are in the <u>same period</u>. Ga is located at the left so it has a larger atomic radius.
c. Sn or Bi ⇒ similar
They are not in the same group neither the same period. Bi is located more at the bottom, so it would be larger than Sn, but Bi is also at the right side, so it would be smaller than Bi. Thus, they have comparable sizes.
d. Se or Sn⇒ Sn
They are not in the same group neither the same period. Se is located at the top and right side compared to Sn, so Sn is the larger atom.
1) Calculate the volume from d = m/V => V = m/d = 2.0*10^-23 g / 1.0*10^14 g/cm^3 = 2.0*10^-9 cm^3
2) Now use the formula of volume for a sphere: V = (4/3)π(r^3) =>
r =∛[3V/(4π)] = ∛[(3*2.0*10^-9 cm^3) / (4π)] = 0.48*10^-3 cm = 4.8*10^-4 cm = 0.00048cm
