Review Introduce new concepts Ionic Bonds Metallic Bonds Molecular Bonds Nomenclature

Review What is a chemical bond? …Forces that keep atoms “together” Valance Shell and Valance Electrons Very important …only these electrons in this outer shell are involved in bonding Metals …location on the table? Properties? Non-Metals Metalliods Transition Metals

New Concepts Electronegativity – The ability of an atom to attract electrons Higher the Electronegativity, the more able the atom is to acquire electrons Electropositivity- The opposite, the ability of an atom to donate electrons Higher the Electropositivity, the more able to donate electrons Octet Rule- All atoms want to have 8 electrons in their outer shell special case is H (is content with only 2 electrons)

Ionic Bonds Usually formed between Metal and a Non-Metal Metal is electropositive, the cation (positive charge) Non-Metal is electronegative, the anion (negative charge) Opposites charges attract The resulting compound is neutral Generally- hard, brittle crystals, high melting points, and conduct electricity when melted or dissolved in water Ex. NaCl, Mg 2 Cl, HCl, NH 3, H2O, KBr

Metallic Bonds Composed of 2 or more metals Metals have a low electronegativitely (tend to loose electrons) Positive metals atoms in a shared electron cloud Positive nuclei bunched together in a ‘sea’ of electrons Very conductive (electrons move easily from atom to atom) Very Ductile, Malleable, and shiny (luster)

Molecular Bonds (covalent) Usually formed between 2 Non-Metals Following the Octet rule, atoms share electrons to complete valance shell Force of attraction between the nuclei and shared electrons (weaker than ionic bonds) There can be several covalent bonds in 1 compound (more on this next lesson) Low melting /boiling points, poor conductivity

Molecular Bonds (covalent) 2 Main Types… Polar and Non-Polar Non-Polar covalent bonds are symmetrical Atoms must have similar electronegativity values Have the same “pull” on the shared electrons Ex. CO 2 Polar covalent bonds are asymmetrical Atoms have different electronegativity values One atoms “pulls” shared electrons closer to its own nucleus Ex. H 2 O

Nomenclature – Ionic compounds Ionic Bonds Metal first then non metal and appropriate ending Most of the time the 2 nd elements ending is “–ide” Exception- polyatomic ions (next slide)

Nomenclature- Polyatomic Ions AmmoniumNH 4 1+ AcetateC 2 H 3 O 2 1- ChlorateClO 3 1- Hydrogen CarbonateHCO 3 1- HydroxideOH 1- NitrateNO 3 1- NitriteNO 2 1- CarbonateCO 3 2- SulfateSO 4 2- SulfiteSO 3 2- Phosphate PO 4 3-

Nomenclature- 7 Acids and 1 Base Hydrochloric acidHCL Nitric acidHNO 3 Acetic acidHC 2 H 3 O 2 Perchloric acidHClO 4 Carbonic acidHCO 3 Sulfuric acidH 2 SO4 Phosphoric acidH 3 PO 4 AmmoniaNH 3

Nomenclature- Metals Metallic Bonds Pure metals use the single element name Steel – mainly iron with some carbon content Stainless steel - steel plus chromium and nickel Brass – copper and zinc Bronze – copper and tin

Nomenclature Dihydrogen monoxide (DHMO) Is this a dangerous chemical that should this be a banned?

Nomenclature- Binary Covalent Bonds Rule 1. The element with the lower group number is written first in the name; the element with the higher group number is written second in the name. Exception: when the compound contains oxygen and a halogen, the name of the halogen is the first word in the name. Rule 2. If both elements are in the same group, the element with the higher period number is written first in the name. Rule 3. The second element in the name is named as if it were an anion, i.e., by adding the suffix -ide to the name of the element. Rule 4. Greek prefixes (see the Table provided at the bottom of this page) are used to indicate the number of atoms of each nonmetal element in the chemical formula for the compound. Exception: if the compound contains one atom of the element that is written first in the name, the prefix "mono-" is not used. Molecules naming game

Nomenclature PreFix Number Indicated mono-1 di2 tri-3 tetra-4 penta-5 PreFix Number Indicated hexa-6 hepta-7 octa-8 nona-9 deca-10

EXTRA-Nomenclature SuffixMeaningExample -ideIon has only one element NaCL sodium chloride -atemost common number of O NClO3 sodium chlorate -iteone less ONaClO2 sodium chlorite -icending for acids in the –ate form HClO3 chloric acid -ousending for acids in the –ite form HClO2 chlorous acid PreFixMeaningExample hypo-one less O than –ite NaOCL Sodium hypochlorite per-one more O than –ate H2O2 Hydrogen peroxide Prefix and Suffix MeaningExample hypo- -icAcid with no O HCL hydrochloric acid