Whilst the general trend that metals are solids and non-metal are gases, liquids and solids hold true and as you progress down the non-metals there are more solids there are some key exceptions.
The shiny metal Mercury at room temperature unlike all metals in the periodic table exists as a liquid. Used by the Ancient Greeks as makeup and to form alloys with other metals Mercury exhibits the peculiar behavior of being a liquid. This is because unlike other metals Mercury is bad at sharing electrons in its metallic bonded structure. This means unlike other metals its keeps hold of its electrons leaving it with a low melting point and poor conductivity of electricity.
Again another liquid in the periodic table, located in Group 7 Bromine is the only other known liquid in the periodic table. Unlike Fluorine and Chlorine as gases and Iodine as a solid Bromine exists as a brown-red liquid. This is because the simple covalent diatomic molecule of bromine Br2 is large enough that the intermolecular forces are strong enough that at room temperature it will not become a gas. What can be seen however is that at room temperature at the surface molecules of bromine will escape so often bromine liquid in a sealed container is accompanied with a brown-red gas.
Next, to its neighbors Oxygen and Nitrogen, it is often thought that Carbon would have been a gas, and the most well-known compound of Carbon Dioxide exists as a gas. However, Carbon exists in allotropes. Allotropes are different physical forms of which an element can exist. Carbon is a very good example of this. The two most common forms of Carbon are Diamond and Graphite. Carbon is commonly considered to be a solid due to the existence of these two giant covalent structures which both have very high melting points.
Particles in a gas are far apart and can move around a lot freely
Metallic bonding is the bonding between metallic ions where the metallic atoms lose their electrons and form positive metal ions
An alloy is a metal structure that has different sized atoms in preventing the layers from sliding over each other and giving it different properties. An example is steel which is a mixture of iron and carbon.
Intermolecular forces are temporary interactions between ions, atoms or compounds that are not considered to be sharing electrons.
Allotropes are different forms of the same element just bonded in different structures. Carbon is a good example as it can be in the form of diamond and graphite with different structures and properties
Giant covalent structures is the term used to describe large non metallic strucutres that are made of many covalent bonds