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Unit 4 Chemical Bonding. ICP Mr. Patel SWHS. Topic Outline. Valence electrons Cations /Anions – The Octet Rule Metallic Bonding Ionic Bonding Covalent Bonding Nomenclature . A Look Back…. So far we have covered (and mastered): Evolution of the Atomic Model
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Unit 4Chemical Bonding ICP Mr. Patel SWHS
Topic Outline • Valence electrons • Cations/Anions – The Octet Rule • Metallic Bonding • Ionic Bonding • Covalent Bonding • Nomenclature
A Look Back… • So far we have covered (and mastered): • Evolution of the Atomic Model • Democritus, Thomson, Rutherford, Bohr, QM • Bohr Model and Bohr Diagram • Quantum Mechanical Model and Orbitals • Rules of Electron Configuration • Writing Electron Configurations
Electrons • Chemical reactions are the breaking and forming of bonds • There are two types of bonds: covalent and ionic (and metallic) • Bonding involves the movement of electrons
Valence Electrons • Valence Electron: electrons in the highest occupied level • These are the electrons that participate in bonding!!!
Valence Electrons • You do not have to draw a Bohr Model every time you need to determine the VE’s • The valence electrons (valency) for an atom is the same as the group number • Note: In general, transition metals have two valence electrons.
Determine the valence electrons for: • Ca • Be • O • Si • H • Ne • Ar • 2 • 2 • 6 • 4 • 1 • 10 • 10
Lewis Dot Structures • Show bonding electrons • These structures show only valence electrons. • How to draw: • Write Symbol for element • Determine group number • Place that many (group number) dots around symbol N B
Lewis Dot Structures 1 2 3 4 5 6 7 8
The Octet Rule • Remember that Noble Gases were very stable • They all have 8 valence electrons (2 for He) • FULL outer shell of electrons • Every element will try to become like a noble gas • The Octet Rule – atoms will try to have a full outer shell (= 8 electrons) when bonding
Cations • Metals tend to lose electrons to have a full outer shell • Cation – positively charge ion • Results from metals losing electrons • Naming: element name + ion • Ex: Na = Sodium but Na1+= sodiumion
Anions • Nonmetals/Metalloids tend to gain electrons to have a full outer shell • Cation – positively charge ion • Results from nonmetals gaining electrons • Naming: element name with –ide ending + ion • Ex: Br = Bromine but Br1- = bromide ion
Cations/Anions • To determine the charge of an element’s ion, look at the group/column that it is in • Group 1: 1+ • Group 2: 2+ • Group 3: 3+ • Group 4: 0 • Group 5: 3- • Group 6: 2- • Group 7: 1-
Lewis Dot Structures for Ions • Draw the normal Lewis Dot structure for the neutral element • Add electrons if gained or remove electrons if lost • Place the appropriate charge 3- N N Nitride ion: Nitrogen:
Draw the Lewis Dot Structure for Phosphorus. • Will this element for a cation or anion? • What charge will it have? • What will be the name of the ion? • What noble gas is it similar to? • Draw the Lewis Dot Structure for the ion.
Draw the Lewis Dot Structure for Barium. • Will this element for a cation or anion? • What charge will it have? • What will be the name of the ion? • What noble gas is it similar to? • Draw the Lewis Dot Structure for the ion.