chemical bonding and calculation notes

Chemical bonding ➔Metals ◆Giant metallic lattice structure ◆Form metallic bonds ◆Have giant metallic structures that consist of positive metal ions surrounded by“sea of electrons”that is delocalised from the metal atoms ●Valence electron of each atom are free to move about the overlapping valence shell ●When the valence electron went to the neighbouring shell, a positive metal ion is formed ●Free electrons act as “electronic glue”, as it holds positive metal ions together ●The metal is a lattice of positive ions in a “sea of electrons”

●Thestrong electrostatic forces of attraction between“sea of electrons” and “immobile” positive metal ions that form the structure of the giant metallic lattice is themetallic bonds ●“Sea of electrons” consists of free electrons, mobile electrons and delocalised electrons) ◆Properties: ●Generally exists as a solid at rtp ○Alarge amountof energy has to be absorbed to overcome tostrongmetallic bond ●Havehighmelting and boiling points ●Good heat conductor ○Sea of electrons are free to move to transfer heat ●Conduct electricity inanystate (aka good electrical conductor) ○Sea of electrons are free to move to carry electricity ●Malleable (can bend/be hammered) and ductile (can be drawn out into thin wire without breaking) ○When force is applied, the neatly arranged layers of metal atoms canenvelopeach other easily ➔Giant covalent bonds ◆Formed between thousands and million of atoms extended 3-dimensionally substance

◆ONLY covalent bonds (duh, that’s why they’re called giant covalent bonds) ◆ Giant covalent bonds → Giant covalent substances ◆Example 1 of giant covalent substance:Diamond ●Has a tetrahedral structure ●Each carbon atom covalently bonded to 4 other carbon atoms ◆ Example 2 of giant covalent substance:Graphite ●Formed by many layer of graphene (a grant molecule) ●Has a hexagonal structure ●Each carbon atom covalently bonded to 3 other carbon atoms ○This leaves 1 free electron per carbon atom not bonded ◆ Table of comparisonbetween Diamond and Graphite Diamond Graphite Structure -Tetrahedral structure -Giant molecule -Each carbon atom covalently bonded to 4 other carbon atoms -Hexagonalstructure -Layers of carbon atoms are held by weak force of attractions -Each carbon atom covalently bonded to 3 other carbon atoms, leaving 1 free electron per carbon atom not bonded substance waswas i n a usedforbandit Tu a re gantmilee

Property 1.High melting point 2.High boiling point 3.Low volatility Same applies here ReasonLarge amount of energy to be absorbed to break the strong covalent bonds between the carbon atoms Same applies here Property 4.Non-electrical conductor4. Electrical conductor ReasonNofree moving ion or electron to carry electric current Onefree electron per carbon atom to carry around electric current Property 5.Hard 5. Soft and slippery ReasonLarge forceneeded to break thestrong covalent bonds between the carbon atoms Low forceneeded to break theweak intermolecular forces of attractionto allow to