3. Calculate the number of particles for each of the following: a) 2.5 mol Ca
b) 7.26 mol Al
c) 3.89 mols
d) 1.35 mol Pb

a.  1.505 x 10²⁴

b.  4.37 x 10²⁴

c.  2.34 x 10²⁴

d.  8.127 x 10²³

Given

Number of moles of elements

Required

The number of particles

Solution

1 mol = 6.02 x 10²³ particles(molecules, ions, atoms)

Can be formulated :

N = n x No

No = Avogadro's number

n = mol

a. 2.5 mo Ca x 6.02 x 10²³ = 1.505 x 10²⁴

b. 7.26 mol Al x 6.02 x 10²³ = 4.37 x 10²⁴

c. 3.89 mol S x 6.02 x 10²³ = 2.34 x 10²⁴

d. 1.35 mol Pb x 6.02 x 10²³ = 8.127 x 10²³

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72