For complex questions, you should add more points. Nonetheless I'll still answer it.
At room temperature, substances exist in various states of matter—solid, liquid, or gas—based on their molecular or atomic structure and the intermolecular forces at play. Let's explore why different substances exhibit these states at room temperature:
Solid:
Solids have a definite shape and volume because their particles (atoms, ions, or molecules) are closely packed together in a fixed, organized pattern. The intermolecular forces, such as van der Waals forces or chemical bonds, are strong enough to keep the particles in a fixed position. The particles vibrate but do not move from their positions, maintaining the solid shape.
Liquid:
Liquids have a definite volume but no definite shape. The particles in a liquid are still closely packed, but they are not in a fixed position like in a solid. The intermolecular forces are weaker than in solids, allowing particles to move and flow past each other. The particles have more energy and are in constant motion, but they are still attracted to each other, keeping them close and maintaining the volume of the liquid.
Gas:
Gases have neither a definite shape nor volume. The particles in a gas are widely spaced and have high kinetic energy. The intermolecular forces are very weak, allowing the particles to move freely and independently, filling the available space. Gases take the shape and volume of their container. The kinetic energy of gas particles is high enough to overcome the attractive forces, leading to a highly disordered and expansive state.
The state of a substance at room temperature depends on factors such as temperature and pressure. For example, increasing the temperature can cause a solid to melt into a liquid and further heat can turn the liquid into a gas (melting and boiling points). Conversely, decreasing temperature can cause a gas to condense into a liquid and then solidify into a solid (condensation and freezing points).
These states of matter are fundamental in understanding the behavior of various substances and are influenced by the energy and interactions between their constituent particles.