chemistry: bonding and lewis structure

covalent bond

sharing electron pairs

nonpolar covalent

identical

polar

unequal attraction for the shared electrons

high electronegativity

strong attraction for electrons (halogens- fluorine)

polar covalent

bonds that have 5%-50% ionic character

ionic character

The greater the electronegativity difference between two bonded atoms, the greater the percentage of ___ in the bond

valence electrons

electrons in the formation of a chemical bond

ionic bond

bond that results from the electrostatic attraction between positive and negative ions

how does a covalent bond hold two atoms together

A pair of electrons is attracted to both nuclei of the two atoms bonded together

electronegativity

determines whether or not the bond will be polar

electronegativity greater than 1.7

ionic

exceptions from the octet rule

hydrogen, boron,, beryllium, phosphorus, sulfur, xenon

resonance structures

show delocalized electrons

NH3

ammonia

H20

water

CH4

methane

C2H2

Acetylene

The atoms in a polyatomic ion are held together with

covalent bonds

polyatomic ions combine with ions of opposite charge to form

ionic compounds

in metals the valence electrons are

shared by all surrounding atoms

as light strikes the surface of a metal, the electrons

absorb and re-emit the light

strength of the metallic bond

increases left to right across

metals

outer electrons in s orbitals

nonmetals

outer electrons in p orbitals

what makes metals good conductors

mobility of electrons

ionic compound

A compound that consists of positive and negative ions

what determines whether a molecule is polar

shape of molecule, electronegativity difference

attraction between molecules

dipole-dipole, london dispersion, hydrogen bonding

dipole-dipole

attractions between oppositely charged regions of polar molecules

London dispersion forces

weakest

hydrogen bonding

where a hydrogen atom is bonded to a highly electronegative atom is attracted to an unshared pair of electrons of an electronegative atom in a nearby molecule

water (H20)

bent, 104.5 angle, polar, 2 lone pairs (4 dots on O) and 2 covalent bonds (lines connecting H to O)

exponent on element

tells how many symbols you use on the lewis diagram

Steps of Lewis structure

1. determine which is central (least EN)

1A. To find the least electronegative, use how far away it is from fluorine and oxygen

2. Count v e- (add up all of valence electrons)

3. placing lone electron pairs on the outer atoms until each outer atom fulfills the octet. Place any rem lone electron pairs on the central atom.

4. if necessary add double/triple bonds to complete octet/duet

5. Formal charge (cation/anion) FC = # of valence electrons - # of lone pair electrons - ½(number of bonding electrons)

dots

pairs, count for 2 valence electrons

ionic bonds with models

opposite charge, don't share ve- , don't have - bc that is represented in covalent only

steps

find how many ve-, and put however many bonds needed to complete octet rule (use - for covalent)