Unit-3 Chemical Compounds CHAPTER 15

Definitions: VALENCE ELECTRON: electron(s) found in the outermost shell of an atom … it helps determine that atom’s chemical properties CHEMICAL BOND: an interaction that holds atoms or ions together … combined atoms will form molecules or ionic compounds ION: a charged particle that forms when an atom or group of atoms gains or loses 1 or more electrons … an Ionic Bond forms when electrons are transferred from one atom to another … this results in a positive ion and a negative ion

more Definitions: COMPOUNDS IONIC COMPOUND: made up of oppositely-charged ions … property characteristics (usually) : brittle at room temp … high melting points … highly soluble … electricity-conductors … COVALENT COMPOUND: formed by the sharing of electrons … most compounds are Covalent property characteristics (usually): low melting points … low solubility … electricity non-conductors …

more Definitions: ACIDS and BASES ACID: any compound that increases the number of hydronium (H 3 O + ) ions when dissolved in water … property characteristics (usually) : sour flavor … change colors in indicators … react with metals … electricity-conductors … BASE: any compound that increases the number of hydroxide (OH - ) ions when dissolved in water property characteristics (usually): bitter flavor … change colors in indicators… slippery … electricity conductors …

more Definitions: ACIDS and BASES Indicators: identifies whether a solution contains an acid or a base Neutralization Reaction: the reaction of an acid and a base to form a neutral solution of water and a “salt” (leftover ionic compound) H 3 O + + OH - = 2H 2 O + salt pH: a value (0 to 14) used to express acidity or basicity (alkalinity) 0 … 1 … 2 … Increasing Acidity Increasing Basicity … 12 … 13 … 14 Neutral (7)

ACIDS and BASES: pH Scale

more Definitions: ORGANIC COMPOUNDS ORGANIC Compounds: covalent compounds made of Carbon-based molecules. INORGANIC Compounds : any compound not considered Organic Hydrocarbon: Organic compounds that contain only Hydrogen and Carbon

Chemical Bonding CHAPTER 13

Definitions - review CHEMICAL BOND: an interaction that holds atoms or ions together … combined atoms will form molecules or ionic compounds ION: a charged particle that forms when an atom or group of atoms gains or loses 1 or more electrons … an Ionic Bond forms when electrons are transferred from one atom to another … this results in a positive ion and a negative ion MOLECULE: the smallest unit of a substance that retains all the physical & chemical properties of that substance

Definitions - review VALENCE ELECTRON: electron(s) found in the outermost shell of an atom … it helps determine that atom’s chemical properties “Lewis” ELECTRON-DOT Diagram: model that shows only the valence electrons in an atom … start with 1 on each side

Electron-Dot examples: Valence electrons … similar by Group Groups 1,2…3teen,4teen,5teen,6teen,etc

Wrap-Up / Main Points Ionic vs Covalent vs Metallic Transferred (lost/gained) vs Shared vs “Swimming” electrons Metals & non-Metals … same-element atoms … Bonds form Compounds & Molecules

Chemical Reactions CHAPTER 14

Chemical Rxn definitions Precipitate: a solid substance formed in a solution as the result of a chemical reaction “oxide”  a chemical compound that contains at least one oxygen atom and one other element in its chemical formula Script (root word): writing (script for a play … scriptures from a bible) Prefixes  super = higher/above … superscripts = math exponents … x 2 sub = lower/beneath (submarine) … subscript = H 2 To determine # of atoms in a molecule: Coefficient x Subscript

Chemical Rxn definitions

Labeling Chemical Equations/Rxn’s Atom … Coefficient … Molecule … Product(s) … Reactant(s) … Subscript … Yield

Balancing Chemical Rxn’s Law of Conservation of Mass (Lavoisier) Mass cannot be created or destroyed in chemical & physical changes … the total mass of the reactants = the mass of the total mass of the products R (g) = P (g)