* Radon (Rn) and Neon (Ne) are noble gases. They are extremely unreactive because they have a full outer shell of electrons, making them very stable. They don't readily form bonds with other elements, including hydrogen.
* Calcium (Ca) is an alkaline earth metal. While it can react with hydrogen to form calcium hydride (CaH2), this compound is not an acid. Acids are generally defined as substances that donate protons (H+) when dissolved in water. Calcium hydride is a base, as it reacts with water to release hydroxide ions (OH-), increasing the pH.
What makes an acid?
* Hydrogen (H) in its ionic form (H+) is the key component of acids.
* Acids typically have a sour taste, can turn blue litmus paper red, and react with bases to form salts and water.
Examples of acids:
* Hydrochloric acid (HCl)
* Sulfuric acid (H2SO4)
* Nitric acid (HNO3)
