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What is ionization energy trend?

Answer 1

Ionization energies decrease down a Group but INCREASE across a Period, from left to right.

As a physical scientist you should seek out the data. As nuclear charge, #Z#, increases, the nucleus has greater electrostatic attraction for the valence electrons. The result is that (i) atomic radii decrease, and (ii) ionization enthalpies increase ACROSS the Period from left to right.

Down a Group, the valence electron is further removed from the nuclear charge, and inner electrons tend to shield #Z#. Ionization energies thus decrease.

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Answer 2

Natalie Anton

The ionization energy trend refers to the pattern observed in the energy required to remove an electron from an atom or ion. Across a period (from left to right) in the periodic table, ionization energy generally increases due to increasing nuclear charge and decreasing atomic size. Down a group (from top to bottom), ionization energy generally decreases due to increasing atomic size and shielding effect from inner electrons.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.