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Lewis Structures. Electron Dot Notation. Electron Dot Notation: an way to write the electron configuration where only the valence electron are shown, indicated by dots around the elements symbol. Ex: Fluorine How many valence electrons?. F. Electron Dot Notation. Nitrogen
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Electron Dot Notation • Electron Dot Notation: an way to write the electron configuration where only the valence electron are shown, indicated by dots around the elements symbol. • Ex: Fluorine • How many valence electrons? F
Electron Dot Notation • Nitrogen • Valence Electrons? • Helium • Valence Electrons? N He
Electron Dot Notation • Practice: • Al • O • Be • C
Molecules • Molecule: A neutral group of atoms held together by covalent bonds • What does covalent mean? • Octet Rule: Chemical compounds tend to form so that each atom has an octet of valence electrons (except H and He) • Molecules for when atoms share electron in order to have 8.
Lewis Structures • Fluorine has 7 valence electrons. To get 8 it can share one with another fluorine atom. • We now have an F2 molecule. F F
Lewis Structures • The electrons being shared are called bonded pairs of electrons and can also be represented by a line. F F F F
Lewis Structures • Pairs of electrons that are not used in bonding are called lone pairs. • How many lone pairs does an F2 molecule have? F F
Lewis Structures • CH3Cl • NH3 • H2O • HCl
Lewis Structures • Practice: • SiH4 • SF2 • Br2
Multiple Bonds • Some atoms will share more then one pair of electrons. This is called a double bond O O
Multiple Bonds • N2 • This is a triple bond • CH2O • HCN • C2H4
Lewis Structures • Practice: • CO2 • C2Cl2 • BrCS
Diatomic Molecule • Diatomic Molecule: A molecule containing two atoms • There are 7 elements that are naturally found as diatomics • H2, N2, O2, F2, Cl2, Br2, I2