Saturday, 27 August 2011

Chemical Bonding


Why atoms bond:
v  Noble gases are stable
v  Atoms bond to achieve electronic configuration of a noble gas
v  Do so by transfer or sharing of electrons with other atoms
v  Atom will achieve stability by having an electric configuration of a noble gas
Ø  2 electrons in 1st shell
Ø  8 electrons in 2nd shell
Chemical bonding:
v  Ionic bonding
Ø  Usually formed between non-metals and metals
Ø  Is the electrostatic force of attraction between oppositely charged ions in an ionic compound
Ø  Example: sodium chloride
§  Sodium passes one electron to chlorine so that both can achieve a full valence
§  Have opposite charges
§  Attract with each other
§  Forms an ionic bond
v  Covalent bonding
Ø  Form bonds by sharing electrons to gain electronic configuration of a noble gas
Ø  Is a bond formed by the sharing of a pair of electrons
Ø  Are generally formed between atoms of non-metal
Ø  Can be formed between atoms of same elements or between atoms of different elements
Ø  Example: Hydrogen gas
§  Hydrogen atom has 1 valence electron
§  Requires one more electron to obtain the electronic configuration of a noble gas
§  Share a pair of electrons between themselves to form hydrogen molecules

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