The number of atoms in 21g of Lithium is: [tex]18.327*10^{23}[/tex] atoms. Number of atoms can be find out by using the number of moles.
The Number of moles:
The number of moles is defined as the given mass over molar mass.
It is given by:
Number of moles = Given mass / Molar mass
Given:
Mass of Li = 21 grams
Molar mass of Li= 6.9 grams/mol
Thus,
Number of moles = 21 g / 6.9 g/mol
Number of moles = 3.043 moles
One mole:
A mole is the amount (10) of material containing [tex]6.02214 * 10^{23}[/tex] particles.
Thus, 3.043 moles of Li will contain = [tex]3.043* 6.02214 * 10^{23}=18.327*10^{23} atoms[/tex]
Thus, the number of atoms of Li are [tex]18.327*10^{23}[/tex] atoms.
Find more information about the Number of moles here:
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