Additional Chemistry Part 3

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Ionic Bonding

Ionic bonding holds oppositely charged ions together in Giant structures. There are strong electrostatic forces of attraction in all different directions. Every ion in the lattice is surrounded by ions which are oppositely charge which makes them stay in a firm place. Sodium Chloride structure has equal numbers of sodium and Chloride ions NaCl. The sodium ions and chloride ions alternate and form a cubic lattice.

(http://chemwiki.ucdavis.edu/@api/deki/files/7597/=edited.png)

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Covalent Bonding

Covalent bonding occurs between non-metals they gain electrons to have a stable arrangement of electrons. They do this by sharing electrons, shared pair of electrons have strongly attracts the two atoms which form a 'covalent bond'. Atoms in group 7 need one electron so they form a covalent bond, group 6 need to gain two electrons and form two covalent bonds. Group 5 can form three bonds and group 4 can form four bonds.

(http://lgfl.skoool.co.uk/uploadedImages/coord11.2%20_covalentbonding1(small)_v2.gif)

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Metallic Structure

The atoms are the same size in metallic elements, they form giant structures so the layers are arranged in regular patterns. You can see some metal crystals on the syrface of some metals. You can grown metal crystals by displacement reaction.  

Higher- Tier - When the metals are packed together the electrons in the highest energy level so the outer shell delocalise and move from one atom to another. Which produces a positive ions in a 'sea' of moving electrons. The delocalised elcetrons strongly attract the positively charged ions which hold the structure together. 

High melting and boiling points There are very strong forces between the fixed bonds and electrons so alot of energy is required to break the bonds. Very good electrical and thermal conductivity. The delocalised electrons are able to move freely in the 'sea'. Therefore are able to carry charge or heat energy.

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Metallic Structures continued ...

Poor Solubility

The electrostatic attraction between ions and electrons is too strong to be broken by the solvent.

metallic bonding (http://scienceaid.co.uk/chemistry/fundamental/images/metallic.jpg)

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