Chapter U1.19, Problem 3E

Interpretation Introduction

Interpretation:

The number of electrons, protons and neutrons of Li + ion needs to be determined.

Concept introduction:

The number of electrons can be determined using the electronic configuration of the atom. The atomic number is equal to the number of protons and electrons of a neutral atom.

Answer to Problem 3E

Name	Atomic number	Protons	Electrons	Neutrons	Mass
Lithium(Li)	3	3	3	4	7
Lithium ion(Li + )	3	3	2	4	7

Explanation of Solution

The symbol for Li atom is as follows:

$\underset{6.94\left(\text{atomicmass}\right)}{Li}$

This is the configuration of Lithium metal according to the periodic table.

$\begin{array}{l}AtomicNumber=Numberofprotons\hfill \\ Numberofprotons=NumberofElectrons\hfill \\ MassNumber=Protons+Neutrons\hfill \end{array}$

According to this equation the atomic number of lithium metal(Li) is 3 so the protons are 3. The number of protons are 3 so the electrons are 3.

$\begin{array}{l}MassNumber=Protons+Neutrons\\ 7=3+?\\ 7-3=4\end{array}$

The neutrons are 4

$1s^{2}2s^1\stackrel{-e^{-}}{{\displaystyle \to }}1s^2$

The lithium metal electronic configuration is 1s² 2s¹ after the loss of electrons the lithium metal converted into lithium ion (Li ⁺ ) that is 1S². Thus, number of electrons is 2.

Conclusion

Thus, lithium ion (Li ⁺ ) has 2 electrons, 3 protons and 4 neutrons.