Chemical Bonding

Compounds Compound: two or more elements bonded together chemically Compounds have different properties than their individual parts

Formulas Chemical formula: tells what elements a compound contains and the exact number of the atoms of each element in the compound Examples: NaCl = 1 sodium and 1 chlorine H₂O = 2 hydrogen and 1 oxygen C₆H₁₂O₆ = 6 carbon, 12 hydrogen and 6 oxygen

Atomic Stability Atomic Stability: Atoms with a full outer energy level are more stable Atoms form compounds to gain stability by losing, gaining or sharing electrons

Chemical bonds Chemical bonds: the force that holds atoms together in a compound

Ions Ion: an atom that has gained or lost an electron Becomes a charged particle because it has either more or fewer electrons than protons Example: Elements in groups 1 and 17 form ions easily Na⁺ Cl⁻

Ions Iodine: “Wanted: one electron to borrow” Potassium: “Available: one electron to lend”

Ionic bonds Ionic bond: when electrons are gained or lost Caused by the attraction of opposite forces Results in a compound with a neutral charge

Covalent bonds Covalent bond: when electrons are shared between 2 atoms Molecule: a neutral compound that is formed during covalent bonding

Covalent bonds Single covalent bonds: made up of 2 shared electrons Example: water H₂O, ammonia NH₃, Sulfur Dioxide SO₂

Covalent bonds Multiple covalent bonds: contains more than one pair of electrons being shared Example: atmospheric nitrogen: N₂

Sharing of Electrons Unequal Sharing of electrons: sometimes the electron spends more time around one of the elements in the compound Polar molecule: a molecule that is slightly positive on one end and slightly negative on the other end because of unequal sharing of electrons Example: water

Polar vs non-polar Nonpolar molecule: a molecule in which electrons are shared equally Example: methane CH₄ ,Hydrogen H₂, chlorine Cl₂, Carbon dioxide CO

Formulas Binary compound: a compound that is composed of two elements Example: potassium iodide = KI, carbon monoxide = CO Oxidation numbers: the number of electrons an atom has gained or lost in order to become stable Examples: Sodium ion = Na⁺¹ Chloride ion = Cl⁻¹

Formulas Polyatomic ion: a positively or negatively charged, covalently bonded group of atoms Example: Baking soda: hydrogen carbonate = HCO⁻₃

Hydrates Hydrate: a compound that has water chemically attached to it Example: cobalt chloride hexahydrate CoCl₂ + 6 H₂O

Prefixes Prefixes: used when naming binary covalent compounds Example: NO = nitrogen oxide NO₂ = nitrogen dioxide N₂O = dinitrogen oxide

Chemical Reactions Chemical Reaction: a change where one or more substances are converted into new substances Reactants: the substances that react Products: the new substances produced

Conservation of Mass Conservation of Mass: Mass cannot be created or destroyed The mass of the reactants ALWAYS equals the mass of the products

Father of Chemistry Antoine Lavoisier: explained the conservation of mass Described what was happening in combustion reactions Experimented on cellular respiration and metabolism

Chemistry Nomenclature: the science of naming things Chemical Equation: a way to describe a chemical reaction using chemical formulas and other symbols NiCl₂(aq) + 2NaOH(aq)  Ni(OH)₂(s) + 2NaCl(aq)

Chemistry symbols  produces + plus (s) solid (l) liquid (g) gas (aq) aqueous (dissolved in water) Heat  reactants are heated Elec.  electric current is applied to reactants Light  reactants are exposed to light