1. during a lab activity, students calculate the density of an element to be 7.78 g/cm3. the density listed on the periodic table is 7.13 g/cm3. calculate the percent error and identify the element. 2. what two sets of units can be used to describe density? why are they interchangeable?

Answer 1) The percent error will be 9.12 and the element is zinc

Explanation : The percent error has the formula as

% error =

∴% error =   = 9.12 %

And the density seems to be close to that of element Zinc which is 7.140

Answer 2) Density has two units as it is defined in terms of mass and volume.

Also, it is a unique property of every element and compound. As the material remains same the density also remains the same. The density is measured in terms of CGS or SI unit. In CGS unit it is g/mL and in SI unit it is Kg/L.

So, in both the cases we tend to multiply 1000 to g it becomes kilogram (Kg) and 1000 unit of mL is liter (L). And it is seen that the value remains the same.

these nuts

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.