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Formation of Compounds

Formation of Compounds. Ch. 4. Forming Compounds. Valence electrons: Out most electrons Ions: - Cations ; positively charged by losing electrons; Na + - Anions ; negatively charged by gaining electrons; Cl - Octet Rule: Atoms are most stable when they have 8 valence electrons

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Formation of Compounds

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  1. Formation of Compounds Ch. 4

  2. Forming Compounds • Valence electrons: • Out most electrons • Ions: -Cations; positively charged by losing electrons; Na+ -Anions; negatively charged by gaining electrons; Cl- • Octet Rule: • Atoms are most stable when they have 8 valence electrons • Isoelectronic: • Having the same number of valence electrons K+ = Ar F = ClXe= Ba2+

  3. Compounds and their Properties Compounds have very different properties than the elements that the are made of

  4. How Compounds Form • Octet rule • Elements was to achieve a “Noble Gas” configuration • Transition metals have a “Pseudo-Noble Gas” configuration • Have a filled outer level (s-level) but space in d-level allows for bonding to occur • Bonding types: • Ionic: Electron “taking” bonds • Covalent: Electron “sharing” bonds

  5. Ionic Compounds • Bond between cations and anions • Cation are always metals • Anion are always non-metals • Compound should have a net charge of “0” • Anion “takes” the electron because it is always more electronegative than the cation • Naming: First element- regular element name Second element- replace ending with “ide” NaCl- Sodium + Chlorine = Sodium chloride KI- BaCl2- Al2O3- Barium chloride Potassium iodide Aluminum Oxide

  6. Ionic Compound Structure • Ionic compounds form crystal lattice • Makes compound brittle and hard • Ionic compounds dissolve and H2O and become free floating ions • Electrolytes • Compound that helps electricity flow through water

  7. Ionic Compound Lewis Dot Structure • When drawing ions set to form a compound use different colors or dot styles for each element • When drawing the ionic compound: • The cation has no dots • The anion must have a full shell (8 dots) • Net charge of the compound is 0

  8. Ionic Compound Lewis Dot Structure • Al3+ + Cl- ?

  9. Covalent Compounds • Electron “sharing” between non-metals; use the term “molecule” • Weaker than ionic bonds • Can form multiple bonds between multiple pairs of electrons • 1 pair is a single bond (weakest) • 2 pair is a double bond • 3 pair is a triple bond (strongest) • Bonding occurs to achieve “Noble Gas configuration”

  10. Covalent Compound Lewis Dot Structure • Draw ions using normal dot structure rules • Draw the molecule with bond lines replacing the shared electrons

  11. Covalent Compound Naming • Naming rules differ from ionic compounds • First element uses the normal element name • Second element uses “ide” ending rule • Number of each element must be stated CO2- N2O4- H2O- Dihydrogen oxide Dinitrogen tetraoxide Carbon dioxide

  12. Covalent vs. Ionic Compounds • Interparticle Forces • Forces between particles of a substance Ionic compounds have very strong interparticles forces due to + and – charges from the ions -commonly found as solids Covalent compounds have no charge so their interparticles are very weak -commonly found as liquids and gases -solid covalent compounds melt at low temps. -many do not dissolve in water

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