4.5 Metallic Bonding and 4.6 Lewis Structures And Formal Charge Flashcards
How are metals constructed?
Made up of a regular lattice arrange,ent of positive ions surrounded by a sea of delocalised electrons, they have a giant structure.
What is the definition of metallic bonding?
An electrostatic attraction between the positive ions in the lattice and the delocalised electrons.
Why does magnesium have a higher melting point than sodium?
Mg forms a 2+ ion compared to Na with forms a 1+ ion. This means that the electrostatic attraction between the ions and the delocalised electrons is stronger in Mg. The Mg 2+ ion is smaller than the Na+ ion and therefore the delocalised electrons are closer to the nucleus of the positive ion in Mg and more strongly attracted.
What are some physical properties of metals?
Good conductors of electricity - delocalised electrons are free to move around.
Malleable - may bee hammered into shape since the layer of metal ions can slide over each other without affecting the bonding. The boding is non directional the metal ions attract the delocalised electrons in all directions.
What are alloys?
Homogenous mixtures of two or more metals, or of a metal with a non metal.
Why are alloys stronger than pure metals?
A different sized atoms will prevent planes of metal atoms sliding over each other.
What can the formal charge on atoms be used for?
Can be used to select the most appropriate Lewis structures for a particular molecule/ion.
How can formal charge be worked out?
(number of valence electrons in the uncombined atom) - 1/2(number of bonding electrons) - (number of non bonding electrons).
Which is the preferred Lewis structure?
The one in which the formal charges on individual atoms are closest to zero.
