[blokeybloke]

Hey guys,

I was just wondering why metal solids are reactive. Don’t the metal atoms become stable once they become cations and form metallic bonds with delocalised electrons?

Thanks

[Borek]

Don’t the metal atoms become stable once they become cations and form metallic bonds with delocalised electrons?

Apparently they don't.

Please remember "stable" is almost always a relative concept, we can usually say what is more stable at given conditions, but nothing is stable forever.

[blokeybloke]

Don’t the metal atoms become stable once they become cations and form metallic bonds with delocalised electrons?

Apparently they don't.

Please remember "stable" is almost always a relative concept, we can usually say what is more stable at given conditions, but nothing is stable forever.

Hi thanks for the help although reactivity is still a concept that is quite confusing to me. For example, when we say chlorine is very reactive do we mean that a chlorine atom (Cl) is reactive or do we mean that Cl2 is reactive. If it is the latter then why is that the case? In a Cl2 molecule, don't both chlorine atoms have 8 electrons in their outer shell?

[Borek]

For example, when we say chlorine is very reactive do we mean that a chlorine atom (Cl) is reactive or do we mean that Cl2 is reactive.

Both, although atomic Cl exists only in rather exotic conditions, so we mostly mean Cl₂.

If it is the latter then why is that the case? In a Cl2 molecule, don't both chlorine atoms have 8 electrons in their outer shell?

Again - it is relative. Yes, in Cl₂ both Cl atoms have their octets filled. They are more stable (less reactive) than atomic Cl. They are still much more reactive than most other elements though. They will be much more stable after they are converted to two Cl^- anions, each with its own octet. But - given right conditions - Cl^- can still easily react, for example when put in solution with Ag⁺ it will immediately create a precipitate.

[Enthalpy]

Single atoms, excepted for rare gases, are so reactive that they are extremely uncommon. Under normal conditions, they have already formed molecules. Chemical reactions use to happen between these already formed molecules (or ions too), at least if considering only the reactants and the products. Reaction intermediates, which can be far less abundant than the reactants and products, can be more exotic, like radicals.

The octet rule isn't the whole picture. Some molecules are less stable despite following the octet rule. Cl₂ is such one, which a different theory called molecular orbitals explains nicely.

Some metallic solids are very stable, for instance gold, which forms no oxide with air. Others are not, like caesium which catches fire in air.