Bonding & Forming Compounds

Chemical Bonds When two atoms move close together, their valence electrons interact. Atoms want to become stable Atoms, ions and compounds become stable when they have a full valence shell (also called a “stable octet.”)

Types of Bonds There are two main types of bonds: Ionic Bonds: between cations (+ ions) and anions (- ions) (generally metals and non-metals) 2. Covalent Bonds: between non-metal atoms

Ionic Bonding The non-metal atom “steals” an e- from the metal atom - + The non-metal becomes a (-) ion and the metal becomes a (+) ion Since they are oppositely charged ions, they attract each other and stick together

Electrons are transferred from the lithium to the oxygen e.g.: lithium and oxygen form an ionic bond in the compound Li2O + Lithium Oxygen Electrons are transferred from the lithium to the oxygen 1+ 2- 1+ Li2O has a ratio of 2:1 as shown. Each Li2O has one oxygen ion for every two lithium ions. Li+ O2- Li+ Lithium oxide, Li2O

Covalent Bonding In covalent bonding, atoms overlap slightly, and one unpaired electron from each atom will pair together. A covalent compound is formed when non-metallic atoms share electrons. A shared pair of electrons is called a “bonding pair.” A pair of electrons in the valence shell that is not used in bonding is called a “lone pair.”

e.g.: Hydrogen and oxygen form a covalent bond in the compound H2O + Hydrogen Oxygen Bonding pair Lone pair Each molecule of H2O has exactly one oxygen atom bonded with two hydrogen atoms.

Building Compounds Activity Step 1: Research to find the chemical formula Step 2: Classify as ionic or covalent Step 3: Cut and paste the elements to build your compound