How many atoms are in 1.4 mol of phosphorus trifluoride (PF3)?

Number of atoms in 1.4 mol of Phosphorus trifluoride (PF₃) : 8.428 x 10²³

The mole is the number of particles(molecules, atoms, ions) contained in a substance  

1 mol = 6.02.10²³ particles

Can be formulated

N=n x No

N = number of particles

n = mol

No = Avogadro's = 6.02.10²³

1.4 mol of Phosphorus trifluoride (PF₃), number of atoms :

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.