A. Major Points and Concepts
* What is a bond?
* force that holds groups or 2 or more atoms together and makes them function as a unit
* Bonds
* bond energy
* energy required to break a bond
* the more energy it takes to beak a bond, the stronger the bond
* Types of Bonds
* ionic bonds
* attraction between a strongly positive ion and a strongly negative ion
* covalent bonds
* formed between atoms with electrons that are shared by the nuclei
* Ionic Compound
* compounds formed by ionic bonds
* metals react with nonmetal to form ionic compound
* Electronegativity
* ability of an atom in a molecule to attract shared electrons to itself
* chemists determine values for elements by measuring polarities of the bond between various atoms
* Bonds
* polarity between bonds depends on difference between electronegativity values of the atoms forming bond
* 0 is a covalent intermediate, polar covalent, large as ionic
* Bond Polarity and Dipole Moments
* magnitudes of separated charges times distance between charges
* if it has a polar bond it has a dipole moment
* some poly atomic molecules also have dipole moments
* arrow points towards negative charged center and tail indicates positive center of charges
* Stable Electron Configuration and Charges of Ions
* group 1 metals have charge of 1+
* group 2 metals have charge of 2+
* group 6 metals will have charge of 2-
* group 7 metals will have charge of 1-
* Electron Configuration of Ions
* representative metals from ions by losing enough electrons to achieve configuration of previous noble gas
* nonmetals from ions by gaining enough electron to achieve configuration of next noble gas
* almost all stable chemical compounds of representative elements, all atoms have achieved noble gas electron configuration
* Electron Configuration and Bonding
* when nonmetal and group 1, 2, or 3 metals react to form binary ionic compound
* ions form such a way that valence-electron configuration of nonmetal is completed to achieve configuration of next noble
gas
* valence orbital of metal are emptied to achieve configuration of previous noble gas
* both ions achieve noble gas electron configuration
* when 2 nonmetals react forming a covalent bond, they share electrons in a way completing valence electron configuration of both atoms
* Ionic Compound
* tend to form small crystals
* crystal lattice is arrangement of ions in ionic crystal
* Physical Properties and Ionic Compounds
* states at room temperature- solids
* electrical conductivity- liquid, aqueous (if soluble)
* boiling point and melting point- high
* solubility in water- often high
* thermal conductivity- low
* Octet Rule
* elements want to have 8 electrons on outer shell
* Valence Electrons
* electron on outer shell
* max number of electrons is 8
* S and P orbitals
* Molecular Structure
* geometric structure
* 3-D arrangement of atoms in molecule
* bent-bond angle 109.5º
* Linear structure 180º
* tends to have double/tripple bond
* Trigonal Planar structure 120º
* Tetrahedral structure 109.5º
* Lewis Dot Structure
* determine number of valence electrons for each molecule
* all all valence electrons together
* arrange atoms to form skeleton molecule
* place single pair of electrons between each atom
* add lone pairs to each atom until each has full outer shell
* count valence electrons
* if not equal, start over but add double or triple bond