chemistry chapter 4

covalent bonds

formed by sharing electrons between atoms

each covalent bond represents the

sharing of 2 electrons

molecules

groups of atoms held together by covalent bonds

metal + nonmetal

form ionic compounds

nonmetal + nonmetal form

covalent (molecular) compound

bond length

the optimum distance between nuclei

diatomic gases

Br, I, N, Cl, H, O, F

group number on periodic table =

usual number of covalent bonds formed

exceptions to the octet rule

boron, forms 3 bonds 6 electrons, and elements in the third row and below

single bond

shares one electron pair

double bond

shares 2 electron pairs

triple bond

shares 3 electron pairs

O forms - bonds

double

C+N form - bonds

double and triple

characteristic: smallest component ions

ionic bonds

characteristic: metal + nonmetal

ionic compounds

characteristic: crystalline solids

ionic compounds

characteristic: high melting and boiling point

ionic compounds

characteristic: many are water soluble, conduct electricity in water

ionic compounds

characteristic: smallest component molecules

molecular compounds

characteristic: nonmetal + nonmetal

molecular compounds

characteristic: gas, liquid, or low Mp solid

molecular compounds

characteristic: low melting and boiling point

molecular compounds

characteristic: do not conduct electricity

molecular compounds

characteristic: few are water soluble

molecular compounds

molecular formula

gives numbers and kinds of atoms in one molecule

lewis structure

a representation that shows connections among atoms by using lines for covalent bonds

common bonding pattern: C

4 bonds

common bonding pattern: N

3 bonds, one lone pair

common bonding pattern: O

2 bonds, 2 lone pairs

common bonding pattern: halogens

1 bond, 3 lone pairs

common bonding pattern: H

1 bond

VSEPR

valence shell electron pair repulsion model

VSEPR represents

3d structure of molecules

2 charge clouds

linear

3 charge clouds, 0 lone pairs

trigonal planar

3 charge clouds, 1 lone pair

bent/angular

4 charge clouds, 0 lone pairs

tetrahedral

4 charge clouds, 1 lone pair

pyramidal

4 charge clouds, 2 lone pairs

bent

polar covalent bond

electrons shared unequally

electronegativity

the ability of an atom to attract electrons in a covalent bond

bond polarity

calculated by the difference in electronegativity

0-0.4 electronegativity difference

covalent

0.5-1.9 electronegativity difference

polar covalent

2.0 and above electronegativity difference

ionic

lewis structure of ions

add/subract electrons based on charge

formal charge

number of valence electrons - electrons on atom in molecule

asymmetrical molecules are

polar overall

symmetrical molecules are

nonpolar overall

binary compound

formed by a combination of 2 different elements

naming binary compounds

prefix - first element - prefix - second element(-ide)

mono

1

di

2

tri

3

tetra

4

penta

5

hexa

6

hepta

7

octa

8

nona

9

deca

10