The key idea
Some textbooks instead quote the attachment enthalpy itself. Its sign is opposite. To avoid ambiguity, Mendeleev never mixes these two conventions.
Why it matters
Start with the central idea, then test it against a concrete element or example. A scientific model is useful when we know what it explains — and where its limits are.
A picture to remember
Start with the central idea, then test it against a concrete element or example. A scientific model is useful when we know what it explains — and where its limits are.
Convention used on Mendeleev
Start with the central idea, then test it against a concrete element or example. A scientific model is useful when we know what it explains — and where its limits are.
The key idea
Before calculating, identify what the quantities represent, their units and the direction in which you expect the result to change. For Electron affinity, this simple prediction is a useful check: it forces you to connect the symbols or vocabulary to a physical or chemical meaning.
Start with the central idea, then test it against a concrete element or example. A scientific model is useful when we know what it explains — and where its limits are.