Question: I read this background article the other day: The increase in electrons across the periodic table explains why elements go from metals to metalloids and then to nonmetals from left to right across the table. Look at period 2 in Figure below as an example. Lithium (Li) is a metal, boron (B) a metalloid, and fluorine (F) and neon (Ne) are nonmetals. The inner energy level is full for all four elements. This level has just one orbital and can hold a maximum of two electrons. The outer energy level is a different story. This level has four orbitals and can hold a maximum of eight electrons. Lithium has just one electron in this level, boron has three, fluorine has seven, and neon has eight.  I am facing a new situation today: James is memorizing the periodic table and some of the features of the elements on it. He is currently working on the fourth row which starts with Potassium (K) on the far left and ends with Krypton (Kr) to the far right.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which of the two elements, Potassium (K) or Krypton (Kr) is a metal?
Answer:
Potassium (K)