Identify an element that is NOT a semi-metal. 

The correct answer is Caesium.

 Key Points

•  A semi-metal, also known as a metalloid, is an element that has properties of both metals and non-metals. It typically has a shiny appearance, but is brittle and can be a poor conductor of electricity.
•  Cesium is a highly reactive alkali metal and is not a semi-metal. It is a soft, silvery-golden alkali metal with a melting point of only 28.5, making it one of the few metals that are liquid at or near room temperature.
• The chemical elements known as semimetals or metalloids are those that share characteristics with both metals and nonmetals.
• Important semiconductors and metalloids are frequently utilized in computers and other electrical devices.
• Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium, and Tennessine are examples of semimetals.
• Metalloids are often solids that have a shiny appearance and are brittle. They function as insulators while they are at room temperature, but transform into conductors when they are heated or mixed with other elements.
• On the periodic table, metalloids are arranged in a zigzag pattern between boron and aluminum and continue down to polonium and astatine.

Additional Information 

•  Germanium is a semi-metal, with properties similar to both silicon and metals. It is used in the production of semiconductor devices, infrared optics, and as a catalyst.
•  Arsenic is also a semi-metal, with properties similar to both metals and non-metals. It is used in the production of pesticides, semiconductors, and as a doping agent in the production of transistors.
•  Silicon is a semi-metal and is widely used in the production of semiconductors, solar cells, and other electronic devices.