Chem Notes Igcse
IGSCE Chemistry Notes
Oxides
Oxides are used to determine whether an element is a metal or a non-metal.
Most non-metals are classed as acidic oxides. While most metals are classed as basicoxides.
Acidic Oxides * Reacts with water to form acids * Neutralises alkaline solution to form salt + water
Basic Oxides * Neutralises acidic solutions to form salt + water
Amphoeteric Oxides * These are non-metals which display both acidic and basic properties
Alkaline Oxides * Reacts with water to form alkaline solutions
Neutral Oxides * Do not display either of the acidic or the basic oxides’ properties.
Giant Covalent Structures
There are 2 examples of Giant covalent structures: Diamond & Graphite
They are both allotropes of carbon, meaning they are both different types of the physical form of Carbon.
Diamond
Structure: Giant covalent lattice of carbon atoms.
Each Carbon atom is bonded to 4 others which tetrahedrally surround the atom.
They have a high melting point as a large amount of heat energy is needed to break their bonds.
They are unable to conduct electricity as they have no free mobile electrons to carry the current.
Diamond is very hard as there are many bonds within the substance. It is the hardest natural substance and is often used in drilling.
Graphite
Structure: Arranged in layers of 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 the same reasons as diamond. However, it is not hard like diamond but in fact very soft.
There are weak forces between the layers of atoms. They are able to slide over each other and therefore able to act as a lubricant.
Covalent Bonding
Definition: When an atom shares one or more pairs of electrons between atoms to obtain the electronic configuration of a noble gas.
Covalent bonds appear in
Oxides
Oxides are used to determine whether an element is a metal or a non-metal.
Most non-metals are classed as acidic oxides. While most metals are classed as basicoxides.
Acidic Oxides * Reacts with water to form acids * Neutralises alkaline solution to form salt + water
Basic Oxides * Neutralises acidic solutions to form salt + water
Amphoeteric Oxides * These are non-metals which display both acidic and basic properties
Alkaline Oxides * Reacts with water to form alkaline solutions
Neutral Oxides * Do not display either of the acidic or the basic oxides’ properties.
Giant Covalent Structures
There are 2 examples of Giant covalent structures: Diamond & Graphite
They are both allotropes of carbon, meaning they are both different types of the physical form of Carbon.
Diamond
Structure: Giant covalent lattice of carbon atoms.
Each Carbon atom is bonded to 4 others which tetrahedrally surround the atom.
They have a high melting point as a large amount of heat energy is needed to break their bonds.
They are unable to conduct electricity as they have no free mobile electrons to carry the current.
Diamond is very hard as there are many bonds within the substance. It is the hardest natural substance and is often used in drilling.
Graphite
Structure: Arranged in layers of 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 the same reasons as diamond. However, it is not hard like diamond but in fact very soft.
There are weak forces between the layers of atoms. They are able to slide over each other and therefore able to act as a lubricant.
Covalent Bonding
Definition: When an atom shares one or more pairs of electrons between atoms to obtain the electronic configuration of a noble gas.
Covalent bonds appear in