Why the first electron gain enthalpy of oxygen negative while the second one is positive?
When an electron is added to Oxygen atom to form O- ion, energy is released. Hence, first electron gain enthalpy of oxygen is negative. But when another electron is add to O- ion to form O2- ion, it feels stronger electrostatic repulsion. That’s why the 2nd electron gain enthalpy of oxygen is positive.
Why is the second electron gain enthalpy negative?
Why is the second electron gain enthalpy negative (i.e. energy is absorbed)? Second is to be added to negatively charged ions which will repel the incoming electron. The energy required to overcome repulsion is more than energy released on adding electron.
Why first electron gain enthalpy of Sulphur is more negative than oxygen?
Oxygen is more electronegative and has more density compared to sulphur. Thus, sulphur has more negative electron gain enthalpy.
Why oxygen has positive second electron gain enthalpy?
When an electron is added to an isolated oxygen atom, it becomes uninegative ion. Now if one more electron has to be added, then it will experience a repulsive force or columbic force of repulsion. Therefore , the second electron gain enthalpy is positive for oxygen.
Why is second electron gain enthalpy of oxygen positive?
After adding one electron to the oxygen atom, it becomes a uni-negative ion. Due to this, the size of oxygen atom increases and the nuclear force of attraction on the electrons decreases. So, energy has to be supplied to add the second electron. Hence, the second electron gain enthalpy for oxygen is positive.
Why is the first electron affinity of oxygen positive?
So, it is positive now. 1st Electron Affinity is usually exothermic as the energy released when the nucleus attracts the the additional electron is larger than the energy absorbed to overcome inter-electronic repulsion. 2nd Electron Affinity is always endothermic since an additional electron is added to a negative ion.
Why oxygen has less electron gain enthalpy?
(ii) Due to the small size and compact nature of the oxygen atom, the incoming electron is not accommodated with ease. As a result, oxygen has less electron gain enthalpy with a negative sign than sulphur.
Why the electron gain enthalpy of chlorine and sulphur is more negative?
Chlorine is a smaller atom when compared to sulphur and it requires very less amount of energy to add an extra electron. So, it has more negative electron gain enthalpy than sulphur.
Would you expect the second electron gain enthalpy of oxygen positive or more negative?
Thus, the first electron gain enthalpy of O is negative. But when another electron is added to Oө to form O2- ion, energy is absorbed to overcome the strong electrostatic repulsion between the negatively charged Oө ion and the second electron being added. Thus,the second electron gain enthalpy of oxygen is positive.