Answer: The simplest way to use the periodic table to identify an element is by looking for the element's name or elemental symbol. The periodic table can be used to identify an element by looking for the element's atomic number. The atomic number of an element is the number of protons found within the atoms of that element.
There are ten dL in one litre, so an ideal amount of lead in a litre of blood would be no greater than 400 micrograms (ug)
There's 1000mL in a litre, so we're looking at 0.4ug of lead or less in a millilitre. 1mol of lead atoms weighs about 207.2g, therefore there's about 2.907 × 10^21 atoms per gram, or about 1.163×10^14 atoms in 0.04ug. Therefore there should be no more than 1.2×10^14 atoms of lead per millilitre.