Why is electron gain enthelpy generally exothermic?

In summary, ionization energy is endothermic because energy is needed to overcome the nuclear attraction when removing electrons. However, when an atom gains an electron, it releases energy because there is a net force of attraction between the atom and the electron. Some elements, like halogens, release more energy than others due to their smaller size and increased nuclear charge, making it easier for them to gain electrons. The released energy is a result of the electron becoming bound to the nucleus.
  • #1
takando12
123
5
I understand that we need to supply energy to counter the nuclear attraction when we remove electrons and that is the reason ionization energy is endothermic. However, why does an atom release energy when we add an electron to it? And also why do some elements( like the halogens) release more energy than the rest? I can understand that it is easier for them to gain electrons than the others because of small size and increase in nuclear charge and I guess it just goes to the first question again.
Please help.
 
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  • #2
takando12 said:
I understand that we need to supply energy to counter the nuclear attraction when we remove electrons and that is the reason ionization energy is endothermic. However, why does an atom release energy when we add an electron to it? And also why do some elements( like the halogens) release more energy than the rest? I can understand that it is easier for them to gain electrons than the others because of small size and increase in nuclear charge and I guess it just goes to the first question again.
Please help.
When an atom gains an electron there must be a net force of attraction between the atom and electron. So for the atom to gain an electron, would that require energy being added from the surroundings?

AM
 
  • #3
Andrew Mason said:
When an atom gains an electron there must be a net force of attraction between the atom and electron. So for the atom to gain an electron, would that require energy being added from the surroundings?

AM
I really can't figure it out. How does the force of attraction relate to whether it releases energy or not?
 
  • #4
takando12 said:
I really can't figure it out. How does the force of attraction relate to whether it releases energy or not?

That electron has some energy associated with it. So when the electron becomes bound to the nucleus, where does all that (or some of that) energy go?
 

1. What is electron gain enthalpy and why is it important?

Electron gain enthalpy (also known as electron affinity) is the energy released when an atom gains an electron. It is an important concept in chemistry as it helps us understand the reactivity and stability of elements.

2. Why is electron gain enthalpy generally exothermic?

Electron gain enthalpy is generally exothermic because when an atom gains an electron, it releases energy in the form of heat. This is due to the attractive force between the positively charged nucleus and the negatively charged electron, resulting in a more stable system.

3. How does electron gain enthalpy vary across the periodic table?

The electron gain enthalpy varies across the periodic table depending on the element's position. Generally, it increases from left to right across a period and decreases down a group. This is because the size of the atom and the effective nuclear charge play a role in the energy released when an electron is gained.

4. What factors can affect the electron gain enthalpy of an element?

The electron gain enthalpy of an element can be affected by several factors, including the size of the atom, the effective nuclear charge, and the electron configuration. Elements with smaller atomic size and higher effective nuclear charge will have a higher electron gain enthalpy. Additionally, elements with half-filled or fully-filled orbitals will have more stable configurations and lower electron gain enthalpy.

5. Why does the electron gain enthalpy of noble gases have a slightly positive value?

The electron gain enthalpy of noble gases has a slightly positive value because these elements have stable configurations with complete outer shells. This means that they do not have a strong tendency to gain an extra electron, resulting in a small energy release or even an energy absorption. Hence, their electron gain enthalpy is slightly positive.

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