Bonding. Why do atoms bond? Atoms bond to get 8 valence electrons! Octet Rule: atoms need 8 valence...
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Transcript of Bonding. Why do atoms bond? Atoms bond to get 8 valence electrons! Octet Rule: atoms need 8 valence...
Bonding
Why do atoms bond?
Atoms bond to get 8 valence electrons! Octet Rule: atoms need 8 valence electrons to be
stable.
2 ways to get 8
1. transfer electrons (forms ions)
2. Share electrons
Ionic bonding
Covalent bonding
Ionic Bonds (Review)
-Atoms lose or gain electrons electrons to become stable (like a noble gas)
-occurs between a metal and non-metal
-occurs between a positive ion and negative ion
Covalent Bonds
-Atoms share electronsshare electrons to become stable (like a noble gas)
-occurs between 2 non-metals
-covalent compounds are called moleculesmolecules
Which of the following are molecular and which are ionic?
NaBr CO2 O3 NO KCl AlBr3
Ionic
Molecular
Ionic
Molecular
Ionic Ionic
Covalent Bonding
2 Types of Covalent Bonds
Nonpolar covalent- electrons are shared equallyequally
Polar Covalent- electrons shared unequallyunequally
Naming and Writing Formulas of
Covalent Compounds
Polar Bonds
-have a partial negative charge on the more electronegative atom
-have a partial positive charge on the less electronegative atom
Nomenclature
Since electrons are shared two elements can bond in different ratios
Ex.: CO Carbon monoxide
CO2
We name covalent (molecular) compounds using prefixes to indicate the number of atoms of each.
Carbon dioxide
Prefixes
1 atom *mono- 6 atoms2 atoms 7 atoms3 atoms 8 atoms4 atoms tetra- 9 atoms5 atoms 10 atoms
hexa- di- hepta-tri- octa-
nona- penta- deca-
* Mono- is only used for the second element
Nomenclature:1) Name the first element that appears in the formula.
2) Name the second element that appears in the formula, changing its ending to –ide.
1. N2O
4
* There are 2 nitrogen atoms and 4 oxygen atomsName: dinitrogen tetraoxide
2. NOnitrogen monoxide
Naming Molecular CompoundsNaming Molecular Compounds
ExamplesNO₂
As₂O5
PCl₃
CCl₄
Nitrogen dioxide
Diarsenic pentoxide
Phosphorous trichloride
Carbon tetrachloride
Writing Formulas for Covalent Compounds
-Prefixes tell you subscripts for elements!
Ex.:
1. Nitrogen trioxide
Nitrogen has no prefix so there is 1 atom of nitrogen
The prefix tri- means there are 3 oxygens
Formula: NO3
Examples
dihydrogen monoxide
sulfur hexafluoride
xenon trioxide
tetraphosphorus trisulfide
H2O
SF6
XeO3
P4S3