Solids:
* Metals: Most metals are solid at room temperature. Examples include iron, gold, silver, copper, aluminum, and titanium.
* Nonmetals: Some nonmetals are solid at room temperature. Examples include carbon (diamond, graphite), sulfur, phosphorus, iodine, and selenium.
* Metalloids: Metalloids can exhibit properties of both metals and nonmetals. Examples include silicon, germanium, and arsenic.
Liquids:
* Nonmetals: Only two elements are liquid at room temperature: bromine and mercury.
Gases:
* Nonmetals: Most nonmetals are gases at room temperature. Examples include oxygen, nitrogen, hydrogen, chlorine, fluorine, helium, neon, argon, krypton, xenon, and radon.
Important Notes:
* Exceptions: While the above is a general guideline, there are exceptions. For example, gallium is a metal that melts slightly above room temperature (around 29.8°C), so it can appear liquid at room temperature.
* Allotropes: Some elements can exist in different forms called allotropes, which have different physical properties. For example, carbon can exist as diamond (solid) and graphite (solid).
* Conditions: The physical state of an element can change with temperature and pressure. For instance, water (H₂O) is a liquid at room temperature and pressure but can be a solid (ice) at lower temperatures and a gas (steam) at higher temperatures.
