[blokeybloke]

What exactly do chemical formulas represent? For example a single sodium atom is represented by Na whereas sodium metal (the solid material) is also represented by Na. I am just confused as to how chemical formulas are used.

[chenbeier]

The formulsa are used to show the molecule of a compound. Na ist for sodium generally, but in combination with chlorine you get NaCl the easierst compound for sodiumchloride .

[Enthalpy]

Writing just Na for the solid is usual, but it's confusing. In that case, it means "one atom taken from solid sodium", which is a molecule.

Na (s) for the solid would be better practice. Feel free to write it that way more often than most people do. Usually, it serves to differentiate from other states, like Na (g) gaseous.

If you noticed that and keep aware of it, you have a chance to avoid a common mistake, in thermochemistry. The reference state of Na (and many more) is the solid. Thermo quantities, for instance the enthalpy of formation, are given by comparison with that state. Though, an atom of Na in the solid has already bonds, which must be broken before forming other molecules, and this takes energy. The writing "Na" hides this.

[Morrano]

Can you somehow highlight that Na is for the solid in this case? It sounds very confusing.

[Enthalpy]

Na (s) for the solid would be better practice.