Chemical Bonds Key Terms Chemically Stable Describes an atom that has a full outer energy level. All noble gases have the maximum number of electrons possible in their outer shell making them stable, and this unreactive. Chemical Bond A force that holds atoms together in a compound. Chemical Formula Shorthand that tells what elements a compound contains and the exact number of atoms of each element in a unit of the compound. Common Name: Chalk Chemical Name: Calcium Carbonate Chemical Formula: CaCO3 Binary Compound A compound composed of two elements. Salt Crystals Common binary compounds include salt (NaCl), ammonia (NH3), and water (H20). Ion A charged particle that has either more or fewer electrons than protons. Ionic Comfort Air Purifier WAS $359.99NOW $329.99 Ionic Bond The force of attraction between the opposite charges of the ions in an ionic compound – result of loss or gain of electron(s). Covalent Bond The attraction that forms between atoms when they share electrons. Polar Molecule Molecule that has a slightly positive end and a slightly negative end. Water is a polar molecule with positive charges on one side and negative charges on the other. Nonpolar Molecule Molecule made of two identical atoms that share the electrons equally, or molecules that are symmetric, such as CO2. The electrical charges in nonpolar Carbon Dioxide are evenly distributed. Oxidation Number Number that indicates how many electrons an atom must gain, lose, or share to become stable. Polyatomic Ion Positively or negatively charged, covalently bonded group of atoms. Carbonate CO32- Sulfate SO42- Hydrate A compound that has water chemically attached to it. = + Carbonate CO3 + Water H2O Carbonic Acid H2CO3 Hydrates are commonly found in skin care products such as moisturizer, shampoo, and lip balm. Hydrates replace the skin’s moisture and repair the tissue damaged by cold and dryness.