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Names and Formulas of

Names and Formulas of. Ionic Compounds. Chemical Bonds . The bond is the force that holds two or more atoms together to form a molecule of a compound- two types Ionic and covalent Atom is to element as H He Fe Na Molecule is to compound H 2 O. Na +   , Cl−, Ca  ++   , S  =  H2SO4.

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Names and Formulas of

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  1. Names and Formulasof Ionic Compounds

  2. Chemical Bonds • The bond is the force that holds two or more atoms together to form a molecule of a compound- two types • Ionic and covalent • Atom is to element as H He Fe Na • Molecule is to compound H2O

  3. Na+  , Cl−, Ca ++  , S = H2SO4 • Formula shown is simplest form of the molecule that is formed when ions combine

  4. Ions • Formed when atoms lose or gain valence electrons • May be + or - ions • They form a stable electron configuration of 8 outer electrons like the noble gases

  5. Cation is + charged ion; loses e- • Anion is – charged ion; gains e- • Ionic bonds form when anion and cations close to each other attract and form a geometric lattice

  6. Force of attraction must be broken to free atoms from each other- usually energy • Physical properties of ionic solids (NaCl salt) like m.p., b.p. hardness, ability to conduct electricity(melted or in solution) attest to strength of bond • Electrolyte: conducts electric current in liquid solution

  7. Atomic Radius • What happens to atoms as they lose electrons? Radius decreases • Opposite? Radius increases • What trends of atomic radius would one expect as atomic number increases? • As one moves from metals to non –metals? • As one moves up and down the table?

  8. Ionization Energy • The energy needed to overcome the attraction between the +positively charged nucleus and the -negatively charged electron • Measured in Joule • Energy required to ionize increases from left to right on pt • Alkali metals –low ionization energies- lose e- readily

  9. Noble gases have EXTREMELY high IE • rare to lose e- • remain stable • He, Ne, Ar, Kr, Xe, Rn

  10. Octet Rule • Atoms tend to lose or gain e- to finalize a full set of 8 valence electrons • This occurs in ionization • Natural occurrence • Makes compound formation possible

  11. PT right side, gain e- - ions or anionsPT left side, lose e- +ions or cations

  12. Electronegativity • Electronegativity is a number that describes the relative ability of an atom, when bonded, to attract electrons.

  13. Where are highest –neg.? • Electronegativity effects properties such as melting and boiling points of substances • Increases from left to right on PT • And decreases from top to bottom

  14. Subscripts in ionic compounds indicate ratio of cations to anions to form electrically neutral atoms H2CO3

  15. Monoatomic ions- form from one atom • -1 is the oxidation state or oxidation number

  16. Polyatomic ions are formed from 2 or more atoms-act as single unit with net charge

  17. Naming • Name of cation first followed by name of anion • NaCl Sodium chloride • Mg SO4 Magnesium sulfate

  18. Charge on cation and anion must = zero for an ionic compound to form • If charge is -1 it can only form bond with other ion +1 • If charge is -2, can form compound with +2 or two ions of +1

  19. Barium Nitrate • Ba (NO3)2 Barium is +2 Nitrate is -1.. (need 2 ions)

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