Explain the formation of (i) Sodium ion, and (ii) Chloride ion, from their respective atoms giving the number of protons and number of electrons in each one of them. What is the reason for a positive charge on a sodium ion and a negative charge on a chloride ion?
Explain the formation of (i) Sodium ion, and (ii) Chloride ion, from their respective atoms giving the number of protons and number of electrons in each one of them. What is the reason for a positive charge on a sodium ion and a negative charge on a chloride ion?
(i) The atomic number of sodium is 11 and its electronic configuration is 2, 8, 1. It needs to lose one electron in order to achieve the nearest noble gas configuration. So, it forms Na+ ion by losing one electron. Because in Na+ ion, the number of electrons is less than the number of protons, therefore there is an overall charge of +1. Hence in Na+ ion,
number of electrons = 10
number of protons = 11
electronic configuration = 2, 10
(ii) Now let us consider chlorine atom. The atomic number of chlorine is 17 and its electronic configuration is 2, 8, 7. It needs to gain one electron in order to achieve the nearest noble gas configuration. So, it forms Cl- ion by gaining one electron. Because in Cl- ion, the number of electrons is more than the number of protons, therefore there is an overall charge of -1. Hence in Cl- ion,
number of electrons = 18
number of protons = 17
electronic configuration = 2, 8, 8
An important point to note is that the number of neutrons remains the same as in the parent atom. So in both Na and Na+ ion, the number of neutrons is 12. Similarly, in both Cl and Cl- ion, the number of neutrons are 18.
(i) The atomic number of sodium is 11 and its electronic configuration is 2, 8, 1. It needs to lose one electron in order to achieve the nearest noble gas configuration. So, it forms Na+ ion by losing one electron. Because in Na+ ion, the number of electrons is less than the number of protons, therefore there is an overall charge of +1. Hence in Na+ ion,
number of electrons = 10
number of protons = 11
electronic configuration = 2, 10
(ii) Now let us consider chlorine atom. The atomic number of chlorine is 17 and its electronic configuration is 2, 8, 7. It needs to gain one electron in order to achieve the nearest noble gas configuration. So, it forms Cl- ion by gaining one electron. Because in Cl- ion, the number of electrons is more than the number of protons, therefore there is an overall charge of -1. Hence in Cl- ion,
number of electrons = 18
number of protons = 17
electronic configuration = 2, 8, 8
An important point to note is that the number of neutrons remains the same as in the parent atom. So in both Na and Na+ ion, the number of neutrons is 12. Similarly, in both Cl and Cl- ion, the number of neutrons are 18.
