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.
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 Metalloids is the term given to the elements in the periodic table that exist between metals and non metals on the right hand side. These are elements that exhibit both properties of metals and non metals.