bonding - Unit B Bonding 1. Ions – charged species. (...

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Unformatted text preview: Unit B Bonding 1. Ions – charged species. ( rearrangement of e’) Cations- positive anions- negative Octect Rule Noble gasses are extra stable because they have eight valence e’. The p orbitals are filled. All other elements want to achieve the noble gas e’ configuration. Positive ions- 2e Mg 12 p 12 e' 8e 2e 2e 1s22s22p63s2 1s22s22p6 Same as Ne Na loses 1 e’ to become Na+ 1s22s22p63s1 --------- 1s22s22p6 + 1e’ 1 Negative Ions- 2 e' 2e 8e 6e 2e S 16 p 16 e' 1s22s22p63s23p4 1s22s22p63s23p6 Same as Ne N gains 3e’ to become N3- 1s22s22p3 + 3e’ -------- 1s22s22p6 Group number will determine the number of electrons given up or accepted Group electrons Group Charge 1 +1 2 +2 3 +3 5 -3 6 -2 7 -1 Metals take on positive charges, Non-metals negative charges Examples H+ Be2+ Al3+ N3- S2- Cl- Exception is H that can be H+ or H-, in water H+ = H3O+ 2. Ionic Compounds – metal (left of periodic table, positive) + non-metal (right of periodic table, negative) Positive and negative ions come together to form a compound. Ionic bond. Physical properties- usually form solid crystals and are poor conductors. 2 Ex. K. .. :Br: + Æ K+ + Br- Æ KBr Æ Mg2+ + Cl- Æ MgCl2 Æ Al3+ + Cl- Æ AlCl3 . Ca: .. :F: + . . Al: .. :Cl: . + Write subscripts when doing ionic compounds they do not change. Two wheels per bike. 3. Covalent Compounds- sharing of e’, two non-metals Look at Cl each atom want one more e’, neither wants to form a positive charge. l C + l C l C l C Diatomic- X2, other diatomic molecules Group 7 (F2,Cl2, Br2)and N2, O2 H2 Look at NH3 3 H N H + H N H H H Covalent bonds- Non-metal, non-metal Group Number Valence e’ 1 4 5 6 7 1 4 5 6 7 Covalent bonds (neutral molecule) 1 4 3 2 1 Must full fill octet O H + H O H H C + Cl l C l C l C C l C l C l C l C Can have multiple bonds. 4 Ex. CO2 : :: : OCO Ex. C2H2 HC CH 4. Exceptions to the octet. a. : : O : :: : . NO : NO2 . N O NO : b. The filling of D orbitals FF PF F F FF F SF F F 10 e' 12 e' c. Fewer than 8 e’. F Be F 4 e' FF B F 6 e' 5. Polarity- only with covalent bonds. (two non-metals) Polar if unequal sharing on electrons, a net dipole moment, unsymmetrical e’ cloud. F F share equally F F H F share un-equally d+ dH F Depends on electronegativity- amount an element attracts e’ pairs. (look at periodic table) F has the highest at 4.0. C H bonds are declared non-polar. 5 Ex. C-Cl d+ d- C Cl 6. Metallic bonds- attraction between negative and positive metal ions delocalized e’. metals combine to form a sort of mixture- properties dependent on concentration. Brass- Cu and Zn Bronze- Cu and Sn One or more elements is an alloy. 6 ...
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This note was uploaded on 09/02/2011 for the course CHEM 2 taught by Professor Harrison during the Spring '11 term at West Valley.

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