Final answer:
Ionization energy is always positive because it represents the energy needed to remove an electron from an atom. Electron affinity can be positive or negative because it indicates the energy change when an electron is added to a neutral atom; a negative value indicates energy is released (atom becomes more stable), while a positive value means energy is required (electron is repelled by the atom).
Step-by-step explanation:
In chemistry, ionization energy and electron affinity are fundamental aspects related to atomic structure and periodic table trends. The ionization energy is always positive because it is the energy required to remove an electron from an atom, which involves breaking the attractive forces between the electron and the nucleus, hence necessitating energy.
On the other hand, electron affinity could be positive or negative. Electron affinity is the energy change that occurs when an electron is added to a neutral atom to form a negative ion. If an atom can easily accommodate another electron in its outermost shell and become more stable, then energy is released, so electron affinity is negative. If forcing an electron into an already full orbit, it will repel it, requiring energy, so the electron affinity is positive.
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