#"Moles of Chromium" = "Mass of chromium"/"Molar mass of chromium"#
#=##(5.67*g)/(51.99*g*mol^-1)##=##0.109*mol#
So what is a mole? It is simply a number, #6.022xx10^23#. It is a fact that #"Avogadro's number"# of chromium atoms have a mass of #51.99*g#. Thus #"Avogadro's number"#, #N_A#, is the link between the micro world of atoms and molecules, to the macro world of grams and litres, that which we can suitably measure in a lab.