Uranium has three common isotopes: U-238 (99.2745%), U-235 (0.7200%), U-234 (0.0055%). Calculate the average atomic mass of uranium. (Round to two decimal places)

237.98

Explanation:

U-238 (99.2745%), U-235 (0.7200%), U-234 (0.0055%).

Multiply mass with percentage of abundance

238 × 99.2745 = 23627.331 %

235 × 0.72 = 169.2 %

234 × 0.0055 = 1.287 %

Add all the percentages.

23627.331 + 169.2 + 1.287 = 237978.818 %

As a whole number it is =

Average atomic mass of Uranium= 237.98 [rounded to 2 decimal places]

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.