CHEMISTRY COMMUNITY

I am aware different periodic tables give different amounts for the atomic mass. Is there a certain decimal place we should round to or should we put in the whole number for the atomic mass and in calculating molar mass?

Hi,

I would just use the entire number that is given from the periodic table, just for extra accuracy. I think it's best to reference the periodic table that's in the textbook since our homework probems are also in there.

My recommendation is 2 to 3 decimal places. I don't think the professor is too strict on the rounding since not rounding at all is super excessive and could leave more room for error when typing it on the calculator to solve a problem.

I would use the entire number and then use sig figs in your final answer.

For more accuracy, you should use all decimal places on the periodic table that is provided. Feel free to round to the amount of sig figs needed at the end of the problem.

Personally I use two to three decimal places but I feel like in test, we should use all of the decimals for extra accuracy in our calculation

I use all of the decimal places given usually, but I stop at 3 if pressed for time. I think using sig figs at the end is the best way to ensure accuracy in your calculations. But, on the exam we all should be given the same table so any problems from slight differences in masses we see on the homework shouldn't be an issue.

I usually use the full number the periodic table gives you in all my calculations, then use sig figs for the final answer.

I think the most accurate way to go about taking masses from a periodic table is by taking the entire number that's given on the sheet and using in your calculations. This way you are sure to prevent rounding error and can then use the sig figs from the problem to round later on

I also usually use the full number given on the periodic table just to be exact as well, but I have noticed some people round their masses from the periodic table to about 2 or 3 decimal places.

I round at the end, so just take the exact number from the periodic table, which is usually to two decimal places, except for hydrogen- I always use 1.008.

It's more accurate to use the whole number when doing the actual problem but you should round your answer and used scientific notation if necessary.

I usually use the entire mass given on the table, so 2 decimal places, and then follow my sig figs from there

I usually use the entire mass given on the table, so 2 decimal places, and then follow my sig figs from there

Atomic numbers are usually carried out to four significant figures such as with hydrogen being 1.008 and carbon being 12.01. So I would just use four significant figures, and it should be fine.

A student asked Professor Lavelle this same question in lecture on Friday. He said he uses all the decimal places, and waits to round until the final answer.

I would recommend using the entire number to begin with so you have the most accurate answer and then when you have the solution you can use sig figs to decide where to round.

Just make sure to stay consistent. I typically always use 2 decimal places and I would recommend not using less but if you wanna use more that's fine too.

I think it is best to use the entire figure given, then round the final answer based on sig figs.

I would say to use the entire number given on the periodic table and then to round your final answer based on the rules of sig figs.