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Definitions. Atom : smallest particle of an element that can exist and still have the properties of the element. Compound : A pure substance that can be broken down into two or more simpler pure substances by chemical means
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Definitions • Atom: smallest particle of an element that can exist and still have the properties of the element. • Compound: A pure substance that can be broken down into two or more simpler pure substances by chemical means • Molecule: group of two or more atoms that function as a unit because the atoms are tightly bound together
MOLECULAR COMPOUNDS • All atoms are nonmetals • Electrons are shared to form a bond • IONIC COMPOUNDS • Metal and a non metal • Electrons are transferred to form cations and anions
Molecular or Covalent bond Valence Electrons are shared
Homonuclear molecules (diatoms)and Heteronuclear molecules(polyatomic molecules)
Homonuclear molecules HONFIBrCl I never fly high over brown clouds
Molecule is the smallest particle of a compound capable of a stable, independent existence Phosphorus exists in a stable form of P-P-P-P Sulfur exists in a stable form of S-S-S-S-S-S-S-S What would be an easier way to write these symbols?
Compounds • H2O # H ____, # O ___ • C6H12O6 # C______, # H _____, # O____ • Mg(OH)2 # Mg_____, # H_____, # O____ • Ca10(PO4)6(OH)10 • 2 H2O #H in each molecule? _____________
Tell whether the following have ionic or covalent bonds • CaCl2MgO • CO2 NH4Cl • H2O HCl • BaSO4 KI • K2O NaOH • NaF NO2 • Na2CO3 AlPO4 • CH4 FeCl3 • SO2 P2O5 • LiBr N2O5
Naming Molecular compounds • Binary compounds (not hydrocarbons) • Two nonmetals • Shared electrons • Name ends in ide • No ions formed • Use Greek prefixes • Mono*, di, tri, tetra, penta, hexa, hepta, octa, nona, deca
Lewis structures • Atoms combine to form molecules so they will have lower energy • Using only valence electrons try and give each atom a complete valence shell (complete octet except Hydrogen) • Then try and give them the number of bonds they want : called covalency
VSEPR • Valence Shell Electron Pair Repulsion
Give the molecular geometry and bond angles of each structure