Final answer:
Chlorine has seven valence electrons and gains one electron in forming an ionic bond with potassium in KCl, resulting in a structure with eight electrons around chlorine, but not all as its valence electrons.
Step-by-step explanation:
The statement that chlorine has 8 valence electrons in the Lewis structure for KCl is false. Chlorine, from the element's position on the periodic table, has seven valence electrons in its neutral state. When it forms an ionic bond with potassium (K) in KCl, it gains one electron to achieve a stable noble gas configuration.
The Lewis structure for KCl represents this with chlorine having a total of eight electrons around it, reflecting its gain of one electron to form the chloride ion, Cl-. However, these are not all valence electrons from the chlorine atom alone; one is from the potassium atom.