Intrinsic Silicon Properties. Read textbook, section 3.2.1, 3.2.2, 3.2.3. Intrinsic Semiconductors – undoped (i.e., not n+ or p+) silicon has intrinsiccharge carriers – electron-hole pairs are created by thermal energy – intrinsic carrier concentration≡n i = 1.45x1010 cm-3, at room temp. In the current SI, the Avogadro constant (NA) is technically defined as the number of carbon-12 (carbon atoms with a total of 12 protons and neutrons) in 12 grams. That number is equal to about 6.022 x 10 23 carbon-12 atoms. This quantity constitutes one mole. Mass number is the sum of protons and neutrons in the nucleus of an atom. The atomic number of silicon is 14, so the number of protons in the nucleus of a silicon atom is 14.

• Silicon 29 Mass Number

What is the average atomic mass of silicon?

Given the following data, calculate the average atomic mass of silicon.

isotope = Si-28
amu =27.9769
abundance(%) =92.18

isotope = Si-29
amu =28.9765
abundance(%) =4.71

isotope =Si-30
amu =29.9738
abundance(%) =3.12 Download mac os x snow leopard theme for windows 7.

1 Answer

Multiply the amu by the percentage of occurrence to arrive at an average atomic mass of #28.0891#

Explanation:

We take the amu of each isotope, multiply it by the percentage of occurrence, and end up with a weighted average:

#27.9769xx.9218+28.9765xx.0471+29.9738xx.0312# (quick note - there is a bit of rounding in here - the abundance percentages add up to 1.01, so the number we calculate is going to be slightly off).

Delicious african thigh. This simplifies to:

#25.7891+1.3648+0.9352=28.0891#

Checking 'the internet' to verify our answer, I found 28.0855 u ± 0.0003 u, so the answer calculated for our question is pretty close.

Silicon 29 Mass Number

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