As in: Helium is a gas but Lithium is a metal, even though they’re right next to each other on the Periodic table.
Or: Carbon is a gas but Silicon is a mineral, even though their chemical behavior is exceedingly similar due to their similar position (on different rows) of the table?
In: Chemistry
Firstly, an elements state depends on its intermolecular bonding, which is the bonding between atoms in a molecule. Not to get into a large amount of details, metals form metallic bonds while non-metals will form covalent bonding. The difference between a gas, solid and liquid is the strength of the intermolecular bonding.
If there is a lack of any significant IMF between atoms, then the element will act as a gas. The amount of energy needed to break these bonds differ on the chemical structure and type of bonding’s present, if the amount of energy needed to break the bonds is very low, for example room temperature, the element will appear as a gas. If the melting/boiling temperature is very high, it will show as a solid etc.
So, Lithium atoms bond via metallic bonding, which is strong and requires relatively large amounts of energy to break the bonds and get it to change state. Helium atoms do not have any attraction between other molecules so do not need a large amount of energy to overcome IMF. Helium is only a solid at below freezing.
That’s the simplest way I can explain without getting into a large amount of details
Carbon and silicon is a different ballpark, and carbon is not a gas, it is a solid, You can have two forms of solid carbon, more known as Graphite and Diamond both with different structures and IMF which change its behaviour completely!
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