Ionisation enthalpy increases across the period. Explain the exceptions , if any observed to this statement. Class 11......answer fast.....I will also mark you Brainliest....no wrong answers
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Ionisation enthalpy increases across the period. Explain the exceptions , if any observed to this statement. Class 11......answer fast.....I will also mark you Brainliest....no wrong answers
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Explanation:
Ionization Energy Trend in the Periodic Table
General periodic trends:
In a group, while moving from top to bottom it decreases.
It increases from left to right across a period.
1. Trends in ionization enthalpy in a group:
The first ionization enthalpy of elements decreases as we move down in a group. While moving down in a group, the atomic number increases and the number of shells also increases. Outermost electrons are far away from the nucleus and thus can be removed easily. The second factor that decreases the ionization energy is the shielding effect due to an increasing number of shells as we move down a group.
2. Trends in ionization enthalpy across a period:
As we move from left to right across a period, the ionization energy of elements increases. This is due to the decrease in the size of atoms across a period. The valence electrons get closer to the nucleus of an atom as we move from left to right due to increased nuclear charge. The force of attraction between the nucleus and the electrons increases and hence more energy is required to remove an electron from the valence shell.
Factors affecting Ionization Energy
Ionization energy depends on two factors:
The force of attraction between electrons and the nucleus.
The force of repulsion between electrons.
The effective nuclear charge felt by the outermost electrons will be less than the actual nuclear charge. This is because the inner electrons will shield the outermost electrons by hindering the path of nuclear charge. This effect is known as the shielding effect. For example, In Na, the 3s1 electrons will be shielded by its core electrons (1s2, 2s2 and 2p6). Generally, the shielding effect is more prominent when the inner orbitals are completely filled.