Chemistry Help! Ive done the work.but can you please check it!?

Question

The Diameter of Chromium(Cr) atom is about 2.4 A( w/ accent above A)...

(A) Express this distance in nanometers..my answer .240

Express this distance in picometers.. my answer 240

(B) How many chromium atoms would have to be lined up to span 1.00 cm. My answer 4.17E-13..or 4.178 x 10 ^-13

Please let me know if they are right or wrong, if wrong, how can I fix them! Thanks!

Answer 1

A - Does this stand for Armstrong unit ? If so, the Armstrong unit is: Å = 1 x 10^(-10) m. (That is 1 by 10 in the power of minus 10 meters).

Diameter of Cr. = 2∙4Å
Diameter of Cr. = 2∙4 x 10^(-10) m. [Nanometers = 10^(-9) m].
Diameter of Cr. = 0∙24 x 10^(-9) m.
Diameter of Cr. = 0∙24 nanometers.

100cm = 1 m.
1 cm = 0∙01 m.
1 cm = 1∙0 x 10^(-2) m.
Now divide the diameter length into the given distance.
= 1∙0 x 10^(-2) m / 0∙24 x 10^(-9) m
= 1∙0 x 10^(+7) / 0∙24
= 4∙1666......x 10^(+7) (A repeating 6).
= 41,666,666∙666666...... Number of Cr atoms.

Answer (A) is correct. Answer (B) should have an exponential of +7, the base number is correct.

Answer 2

First, Your answer for first question is correct. 1 A = 10^-10 m (1 angstrom = 10^-10 meters) and 1 nm = 10^-9 m (1 nanometer = 10^-9 meters)

So, 1 A = 10 nm and 2.4 A/10 = 0.240 nm (right!)

On the other hand, 1A = 100 pm (1 Angstrom = 100 picometers)

So, 2.4 A * 100 = 240 pm

Part (B). Sorry, but it is incorrect whatever the sign you put in exponential number.

If you need to span 1 cm that is equal to 10E-2 m then,

1 cm = 10E10 pm

The question is how many times 240 pm are contained in 10E10 pm?

10E10 pm/240pm = 4.17E+7 atoms will be needed to span 1.00 cm and that is the right answer.

Good luck!

Answer 3

1 angstrom is 10^-10 meter
1 nanometer is 10^-9 meter
1 picometer is 10-12 meter

So you're right for A)

B) Logically, your B is wrong. Many atoms can fit in the distance of 1 cm. Your number suggests otherwise.

Answer 4

(a) is correct since 1 A = .1 nm = 100 picometers

(b) 4.178 x 10 ^ 13

I didn't check the math but this number is more 4.178, not less than, think that it would take A LOT of chromium atoms to span 1.00 cm, not less than 4.17

Answer 5

I would recheck A. I don't think the Agstrom conversion is right. I don't think its even like the one you have. Also, maybe another zero for picometers. Its a factor of 1000. nano to pico

On B, no minus, you are counting how many to make one centimeter, so 4.17 to the 13th, no minus

Answer 6

you lost me