Final answer:
Electron affinity is a measure of how strongly an atom can attract an additional electron, which is true. It reflects the energy released upon adding an electron to a gaseous atom, forming an anion. The trend varies across the periodic table and is not to be confused with electronegativity.
Step-by-step explanation:
Electron affinity is indeed a measure of how strongly an atom can attract additional electrons. To clarify, this is true. Electron affinity (EA) refers to the energy change that occurs when an electron is added to a gaseous atom, resulting in the formation of an anion (negatively charged ion). This is usually an exothermic process for non-metals, meaning that energy is released, and is commonly measured in kJ/mol.
The trend of electron affinity on the periodic table is such that it becomes more negative as we move from left to right across a period, indicating greater energy release and stronger attraction to an added electron. Conversely, electron affinity typically becomes less negative as you move from top to bottom of a group, indicating a decreasing tendency to attract an extra electron.
It's important not to confuse electron affinity with electronegativity, although they are related concepts. Electronegativity is a dimensionless quantity that reflects how strongly atoms attract bonding electrons, and unlike electron affinity, it is not directly measurable but rather a calculated value based on bonded atoms.