2 Ionic Compounds A transfer of electrons creates a strong bond Occurs between a metal and a nonmetal or a metal and a polyatomic ion- held together by electrostatic forceCompounds form in the simplest whole number ratiosCreates true ions- cation (+) and anion (-)All ionic compounds are polar and called a formula unitAlkali and alkaline metal compounds combined with halogens are called salts
3 Properties of Ionic Compounds Compounds are solids at room temperatureCrystalline solids (made of ions) 6 basic shapesHigh melting and boiling points – due to the lattice energy- smaller the ions involved the stronger the bondsConduct electricity when melted or dissolved in water- electrolytes
4 Properties ContinuedMany soluble in water ( the universal polar solvent) but not in nonpolar liquidThe formation of ionic compounds is always exothermic
11 Covalent Compounds Created from sharing electrons Occurs between a nonmetal and a nonmetal or a nonmetal and a polyatomic ionCovalent compounds can either be polar or nonpolarCovalent compounds are called moleculesFormulas are in whole number ratios, but do not need to be simplifiedThere can be single, double and triple bondsDiatomic elements-OHNoHalogens
12 Properties of covalent compounds Bonds have different lengths- the shorter the bond the more energy required to break itTriple bonds are stronger than double bonds, and double bonds are stronger than single bondsCompounds are usually gases or liquids, some however can be solidsLow melting and boiling points than ionic compoundsPoor electrical conductors in all phasesCompounds are either polar or nonpolar- to dissolve, use the rule “like dissolves like”
21 Resonance Structures occur when molecules can arrange themselves to form bonds in different areas yet still obey the octect rule.
22 Metallic Bonds occur because the metals’ nuclei becomes surrounded by a sea of electron This gives metals their physical properties of malleability and ductility
23 Dipole bonds- created from equal but opposite charges London dispersion forces-weak intermolecular forces that occur between nonpolar molecules and is caused by the movement of electronsHydrogen Bonds-occur between hydrogen and a higher electronegative element (O,N, halogens)