Chem Notes Igcse Essay Example for Free

Chem Notes Igcse EssayGiant Covalent Structures There are 2 examples of Giant covalent structures Diamond Graphite They are twainallotropesof carbon, meaning they areboth differenttypes of the physicalform of Carbon. Diamond Structure Giant covalentlatticeof carbon fragments. Each Carbon mote is bonded to 4 others which tetrahedrally surround the constituent. They pick up ahigh melting pointas a large amount of heat energy is needed to breakage their bonds. They areun satisf spelloryto conduct electricity as they have no free mobileelectrons to carry the current. Diamond is veryhardas in that location are many bonds within the substance. It is the hardest natural substance and is often used in drilling. Graphite Structure Arranged inlayersof atoms. Each carbon atom is joined to 3 others, leaving one outer shell electron on each carbon is free to move and able to cary the current. Therefore, they are able to conduct electricity. Graphite also has a high melting point for t he same reasons as diamond. However, it is not hard like diamond but in fact very soft. There are weak forces betweenthelayers of atoms.Theyare able to slide over each other and therefore able to act as a lubricant. Covalent Bonding DefinitionWhen an atom shares one or much pairs of electrons between atoms to obtain the electronic configuration of a dire artillery. Covalent bonds appear innon-metalsand createmolecules. They can even appear in atoms of the same element,H2. MoleculeTwo or more atomschemicallybonded together. The covalently bonded atoms are held together bystrong attractionbetween thebonding pair of electronsand thenucleiof the atoms.Covalent bonds can be classified intotwogroupssimple molecularstructures fiend covalentstructures Simple molecular Structures They have low melting/boiling points dueto the fact thatthereareweakintermolecular forces of attraction. Although, they do have strong covalent bonds. Therefore, they need less heat energy to overcome and break the weak bonds. Some substancessumblimeunder heating. i. e. They turn directly into a gas from a solid. Giant molecular StructuresSee post on giant Molecular structures , Ionic BondingDefinitionThe transfer of one or more electrons between 1 atom to another Why? To obtain the electronic configuration of a noble gas. Thisis because noble gases are inert/very unreactive. If an atomlosesan electron then the atom will form apositiveion. This is because there are now more protons than electrons in the atom. If an atomgainsan electron, the atom forms anegativeion as there are now more electrons than protons in the atom. Thechargeof an ion is related to where the elements position is in the periodic table.