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Molecules and Ions

Molecules and Ions. Chemical bonds. Atoms are held together in compounds by chemical bonds. Covalent Bonds. If atoms are held together by sharing electrons then this is known as a chemical bond Covalent bonds form molecules Molecules are represented by chemical formulas, H2O

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Molecules and Ions

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  1. Molecules and Ions

  2. Chemical bonds • Atoms are held together in compounds by chemical bonds

  3. Covalent Bonds • If atoms are held together by sharing electrons then this is known as a chemical bond • Covalent bonds form molecules • Molecules are represented by chemical formulas, H2O • Or by structural formulas, H – O – H • Or by models

  4. Ionic Bonds • If electrons are transferred then an ionic bond is formed • NaCl • Na ----- Na+ + e- • Cl + e- ------Cl-

  5. Periodic Table • Lots of info • Charge • Atomic Mass • Atomic Number • Metals and Non-Metals • Alkali Metal (I), Alkali Earth Metals (II), Halogens (VII), Noble Gases (VIII), Trans. Met.

  6. Periods • Horizontal rows on PT

  7. Groups • Columns on PT

  8. Naming Simple Compounds • Binary Compounds • These are compounds that are composed of two types elements

  9. Binary Ionic Compounds (Type I) • These compounds contain a positive ion (cation) and a negative ion (anion) • Na+, cation • Cl-, anion

  10. Rules for Naming Type I Binary Ionic Compounds • Cation always named first • Anion always named second • A monoatomiccation is named as the element is named, Na+ is sodium • A monoatomic anion is named as the element but as an –IDE, so Cl- is ChlorIDE • See Table 2.3

  11. Name These • CsF • Cesium Flouride • AlCl3 • Aluminum chloride • LiH • Lithium Hydride

  12. Binary Ionic Compounds (Type II) • Many cations can form more than one type of ions • Especially the Transtition Metals • Use Roman Numerals to indicate charge • Ion of higher charge ends in –ic • Ion of lower charge end in –ous • Fe (II) ferrous, Fe(III) ferric

  13. Naming Type II Binary Compounds • CuCl • Copper (I) chloride • HgO • Mercury (I) oxide • Fe2O3 • Iron (III) oxide

  14. Write the formula for these • Manganese (IV) oxide • MnO2 • Lead (II) chloride • PbCl2

  15. If the cation only has one possible ion thenn DO NOT USE a roman numeral • It is understood what the charge on the ion is

  16. Polyatomic Ions • Some ions are made up of two or more atoms • These are known as polyatomic ions • SO4 -2, OH-, NO3- • See Table 2.5 • Must know formula and charge • Use flashcards

  17. Name these compounds • Na2SO4 • Sodium sulfate • KH2PO4 • Potassium dihydrogen phosphate • Na2CO3 • Sodium carbonate

  18. WriteFormulas • Sodium Hydrogen Carbonate • NaHCO3 • Potassium perchlorite • KClO4

  19. Binary Covalent Compounds (Type III) • These are compounds formed between two non-metals

  20. Rules for Naming Binary Covalent Compounds (Type III) • The first element in the formula is named first • The second is named as if it was an anion • Prefixes denote the number of atoms present • Mono- is never used for the first element as it is assumed. • Mono- is used for the second element, Co • See p. 63

  21. Review

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