Solids tend to be dense and difficult to __1__. They do not flow or take the shape of their containers, like liquids do, because the particles in solids vibrate around __2__ points. When a solid is heated until its particles vibrate so rapidly that they are no longer held in fixed positions, the solid __3__. The __4__ is the temperature at which a solid changes to a liquid. The melting and __5__ of a substance are at the same temperature. In general, ionic solids tend to have relatively __6__ melting points, while molecular solids tend to have relatively low melting points. Most solids are __7__. The particles are arranged in a pattern known as a crystal __8__. The smallest subunit of a crystal lattice is the __9__. Some solids lack an ordered internal structure and are called __10__ solids.