1. 5.2 Ionic and Covalent Bonding I CAN: -RECOGNIZE THAT THE BONDS IN MOST COMPOUNDS FALL ON A CONTINUUM BETWEEN THE TWO EXTREME MODELS OF BONDING: IONIC AND COVALENT -EXPLAIN THAT AN IONIC BOND INVOLVES THE ATTRACTION OF TWO OPPOSITELY CHARGED IONS, TYPICALLY METAL CATION AND A NONMETAL ANION FORMED BY TRANSFERRING ELECTRONS BETWEEN THE ATOMS. -EXPLAIN THAT COVALENT BONDING RESULTS IN THE SHARING OF ELECTRONS BETWEEN TWO ATOMS, USUALLY NONMETALS. -RECOGNIZE THAT COVALENT BONDING CAN RESULT IN THE FORMATION OF STRUCTURES RANGING FROM SMALL INDIVIDUAL MOLECULES TO THREE-DIMENSIONAL LATTICES, LIKE DIAMONDS

2. Bonded atoms usually have a stable electron configuration  Valance electrons want to have full outer shell.  Hydrogen Bond:  INTERMOLECULAR: BETWEEN 2 MOLECULES  Proton-electron attraction, electron clouds cross  Some bonds are able to flex making some bond lengths averages

3. Ionic Bonds  Ionic Bond: formed by the attraction between oppositely charged ions.  Metals with non metals  Salt  Strong  Networks not molecules… why?  1 sodium to 6 chlorines.  Ratios  If every Na+ pairs to one Cl-, then the ratio is 1:1 (NaCl)  Twice as many fluoride ions to calcium = 1:2 (CaF 2 )  Will conduct electricity in water only (ions move free)

4. Electrons move freely between Metal Atoms  Copper can be hammered flat because of bond  Metallic bond: formed by attraction between positively charged metal ions and the electrons around them.  Attraction occurs between one atom’s nucleus and electrons of neighboring atoms.  Close packed energy levels overlap.  Valence electrons are shared collectively by all atoms.  Atoms can slide past each other without breaking bonds.

5. Covalent Bonds  Formed when atoms share one or more pairs of electrons.  Occur in non metal atoms  Solids, liquid, or gases.  Low melting points (<300 o C)  Will not conduct electricity (no charge)

6. Atoms may share more than one pair of electrons

7. Electronegativity (want of electrons)  If shared electrons are equally attracted to nucleus: non polar covalent bond.  If shared electrons are unequally shared: polar covalent bond.  As you go up, atoms becomes smaller, as you move right, you increase positive charge.

8. Polyatomic Ions (Poly=many)  Polyatomic ions: covalently bonded group of atoms that have a charge.  (NH 4 ) 2 SO 4 or N 2 H 8 SO 4  Parentheses remind us that what is inside acts like a single ion.