First ionization energy of group 1 and group 2 elements

In summary, the first ionization energy is the amount of energy needed to remove an electron from the outermost energy level of an atom in its gaseous state. Across group 1 elements, the first ionization energy decreases as you move down the group due to the increasing distance between the outermost electron and the nucleus. This is also caused by the shielding effect of inner electrons, which reduces the attractive force between the nucleus and the outermost electron. Group 1 elements generally have a lower first ionization energy compared to group 2 elements, as they have one outermost electron instead of two. The trend of first ionization energy in group 2 elements is also a decrease, with a slight increase between beryllium and
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ianc1339
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Why does the first ionization energy between group 1 and group 2 elements increase?
The first ionization energy decreases between group 5 and group 6 due to the repulsion between the electrons in the p orbital.

Although I understand that the effective nuclear charge increases between group 1 and group 2 elements, why isn't this the case between group 1 and group 2 elements? Shouldn't the first ionization energy decrease between group 1 and group 2 due to the repulsion between the electrons?
 
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s orbitals extend to the nucleus, so there is a strong increase in potential energy when the nuclear charge increases. This more than compensates for the added electron-electron repulsion.
 
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Related to First ionization energy of group 1 and group 2 elements

What is the definition of first ionization energy?

First ionization energy is the amount of energy required to remove one electron from a neutral atom in its gaseous state.

How does the first ionization energy of group 1 elements compare to that of group 2 elements?

The first ionization energy of group 1 elements is generally lower than that of group 2 elements. This is because group 1 elements have one valence electron in their outermost energy level, making it easier to remove, while group 2 elements have two valence electrons which require more energy to remove.

What is the trend of first ionization energy within group 1 and group 2 elements?

The first ionization energy generally decreases down the group within both group 1 and group 2 elements. This is due to the increasing distance between the outermost electron and the positively charged nucleus, making it easier to remove the electron.

Why does the first ionization energy of group 1 elements decrease more significantly than group 2 elements?

The first ionization energy of group 1 elements decreases more significantly because the outermost electron is shielded by the filled inner energy levels, reducing the attractive force between the nucleus and the electron. In group 2 elements, the outermost electrons are shielded by only one filled inner energy level, resulting in a smaller decrease in first ionization energy.

What is the exception to the trend of first ionization energy within group 1 and group 2 elements?

The exception is helium, which has a higher first ionization energy than the element above it in group 1, hydrogen. This is due to the stability of helium's filled energy level, making it more difficult to remove an electron.

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