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Bonding Notes

This is a sample of our (approximately) 8 page long Bonding notes, which we sell as part of the Chemistry AS Notes collection, a A package written at Manchester High School For Girls Sixth Form in 2013 that contains (approximately) 54 pages of notes across 17 different documents.

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Bonding Revision

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Unit 1: 3 Bonding

BONDING

>Atoms are held together in compounds by chemical bonds
>Bonds between atoms involve ELECTRON TRANSFER.
>atoms bond together in order to achieve a stable electronic structure like a noble gas.
>There are 3 types of chemical bonds - ionic, covalent and metallic.

Ionic bonding
-Compounds formed between metals and non-metals are ionic compounds.
-An ionic compound is made up of a lattice of positively charged metal ions and negatively charged non-metal ions. IONIC BONDING is the force of attraction between the positive and negative ions that form an ionic compound. Electrostatic forces of attraction are formed when electrons are transferred from the metal to a non-metal; the metal atom loses its higher energy electron(s) forming positive ions (cations) whilst the non metal gains electron(s) into its higher energy level to form negative ions (anions). Properties of ionic compounds; The model for an ionic solid consists of a giant ionic lattice containing a regular arrangement of positive and negative ions. I.

Ionic compounds have very high melting and boiling points there are strong electrostatic forces of attraction that exist between the oppositely charged ions in the lattice that require a lot of energy to overcome; therefore high mp and bps.

II.

Ionic compounds can conduct electricity when molten - when melted, the lattice breaks down and the ions are free to move, mobile ions will be able to carry charge through the liquid and therefore can conduct electricity.

III. Ionic compounds are brittle, they shatter when hit or given a sharp blow. A sharp blow can cause the ions in the lattice to displace and similarly charged particles come into contact with each other. The repulsion between like charges causes the structure to shatter. ELECTROSTATIC FORCES OF ATTRACTION INCREASE AS;
- the charge on the ions increase
- the size of the ions decrease.

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Unit 1: 3 Bonding

Covalent Bonding A covalent bond is formed when a pair of electrons is shared between 2 atoms (usually nonmetals) COVALENT BONDING involves the sharing of a pair of electrons between two atoms. A covalent bond is formed when two atomic orbitals. each containing a single unpaired electron, overlap. Each atom is then attracted to the nuclei of both atoms. It is this attraction that holds the atoms together in a covalent bond. COVALENT BONDS are stronger if the degree of overlap between the orbitals is greater. Dot & Cross Diagrams

In the displayed formula, a line between the atoms is used to represent the covalent bond.

If atoms share more than one pair of electrons, more than one line is used.

Coordinate or Dative Covalent Bonding This is where a covalent bond is made between two atoms whereby one of the atoms donates both the electrons - a LONE PAIR - to form the bond.

We represent a dative bond as an arrow.

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