Final answer:
The ion formed when potassium achieves noble-gas electron configuration is a potassium ion or K+. Potassium prefers to lose its one valence electron, resulting in a cation with a +1 charge.
Step-by-step explanation:
The ion formed when potassium achieves a noble-gas electron configuration is a potassium ion, denoted as K+. Potassium has an atomic number of 19, meaning it has 19 protons. In its neutral state, potassium also has 19 electrons. The element has one electron in its valence shell, making it very likely to lose this single electron and form a positively charged ion, which would achieve the electron configuration of the nearest noble gas, argon.
When potassium atom loses one electron, it becomes a potassium cation (K+) with a +1 charge. This is because potassium now has 19 protons (positive charge) and only 18 electrons (negative charge), resulting in an overall positive charge.