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BONDING

BONDING. General Rule of Thumb: metal + nonmetal = ionic polyatomic ion + metal or polyatomic ion = ionic (both) nonmetal + nonmetal(s) = covalent. Ch 8 & 9 – Honors Chemistry. Ionic Bonds. Isn’t it ionic that opposites attract?. Valence Electrons.

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BONDING

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  1. BONDING General Rule of Thumb: metal + nonmetal = ionic polyatomic ion + metal or polyatomic ion = ionic (both) nonmetal + nonmetal(s) = covalent Ch8 & 9 – Honors Chemistry

  2. Ionic Bonds Isn’t it ionic that opposites attract?

  3. Valence Electrons • Knowing electron configurations is important because the number of valence electrons determines the chemical properties of an element. • Valence Electrons: The e- in the highest occupied energy level of an element’s atoms.

  4. Valence Electrons • All elements in a particular group or family have the same number of valence electrons (and this number is equal to the group number of that element) • Examples: • Group 1 elements (Na, K, Li, H): 1 valence electron. • Group 2 elements (Mg, Ca, Be): 2 valence electrons. • Group 17 elements (Cl, F, Br): 7 valence electrons.

  5. Lewis Structures • Electron dot structures show the valence electrons as dots around the element’s symbol: • Li • B • Si • N • O • F • Ne

  6. Lewis Structures • Electron dot structures show the valence electrons as dots around the element’s symbol: • Li • B • Si • N • O • F • Ne

  7. Octet Rule • Noble gas atoms are very stable; they have stable electron configurations. In forming compounds, atoms make adjustments to achieve the lowest possible (or most stable) energy. • Octet rule: atoms react by changing the number of electrons so as to acquire the stable electron structure of a noble gas.

  8. Octet Rule • Atoms of METALS obey this rule by losing electrons. • Na: • Na+: • Atoms of NONMETALS obey this rule by gaining electrons. • Cl: • Cl-: • Transition metals are exceptions to this rule. • Example: silver (Ag) • By losing one electron, it acquires a relatively stable configuration with its 4d sublevel filled (pseudo noble-gas)

  9. Octet Rule • Atoms of METALS obey this rule by losing electrons. • Na: • Na+: • Atoms of NONMETALS obey this rule by gaining electrons. • Cl: • Cl-: • Transition metals are exceptions to this rule. • Example: silver (Ag) • By losing one electron, it acquires a relatively stable configuration with its 4d sublevel filled (pseudo noble-gas)

  10. Octet Rule • Atoms of METALS obey this rule by losing electrons. • Na: • Na+: • Atoms of NONMETALS obey this rule by gaining electrons. • Cl: • Cl-: • Transition metals are exceptions to this rule. • Example: silver (Ag) • By losing one electron, it acquires a relatively stable configuration with its 4d sublevel filled (pseudo noble-gas)

  11. Octet Rule • Atoms of METALS obey this rule by losing electrons. • Na: • Na+: • Atoms of NONMETALS obey this rule by gaining electrons. • Cl: • Cl-: • Transition metals are exceptions to this rule. • Example: silver (Ag) • By losing one electron, it acquires a relatively stable configuration with its 4d sublevel filled (pseudo noble-gas)

  12. Ionic Bonds • Anions and cations have opposite charges; they attract one another by electrostatic forces (IONIC BONDS)

  13. Ionic Bonds • Ionic compounds are electrically neutral groups of ions joined together by electrostatic forces. (also known as salts) • the positive charges of the cations must equal the negative charges of the anions. • use electron dot structures to predict the ratios in which different cations and anions will combine.

  14. Examples of Ionic Bonds Na+Cl- = NaCl • Na Cl • Al Br • K O • Mg N • K P Al3+Br- = AlBr3 K+O2- = K2O Mg2+N3- = Mg3N2 K+P3- = K3P

  15. Criss Cross Method • Criss-cross ionic charges down as subscripts (without +/-) and reduce (to determine lowest whole # ratio of cation:anion) • ANY TIME YOU ADD A SUBSCRIPT TO A POLYATOMIC ION, YOU MUST FIRST PUT THAT ION IN PARENTHESES.

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