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What is the best method to classify a chemical substance - Coggle Diagram
What is the best method to classify a chemical substance
Substance: a chemical element and its compounds in the natural state.
3 types of bonds, 4 types of structures
Covalent network, covalent molecular, metallic, ionic
How are these substances are different
Ionic: Bonding between two or more metallic and non metallic ions, creating a network
They have high melting points and are a good conductor in liquid form
Covalent network: non-metallic atoms creating a lattice
They have high melting point and are poor conductors
Covalent molecular: Bonding between two or more non-metallic atoms to form 8 valence electrons in the outer shell
They have low melting points and have poor conducticity
Metallic: two or more metallic atoms forming a network with positive ions surrounded by a sea of delocalised electrons
They have high melting points and are good conductors of electricity and heat. They are also melleable and ductile
Types of tests
Melting point
(The blue bit goes up to 400 degrees) This gives an indication of whether the substance has a high or low melting point
Wave the test tube containing the substance over the tip of the blue flame.
If the substance melts, this is covalent molecular
If the substance does not melt, this is not covalent molecular
Conductivity in solid state
Using a conductivity tester
Place the electrodes of the conductivity tester in the substance in solid state
If the substance conducts in solid state, this is metallic
If the substance does not conduct in solid state, this is either covalent or ionic
Conductivity in solution
If the substance does not melt, conductivity in molten form (limitation)(+melting point)
Melt the substance in pure water and place the elctrodes of the conductivity tester
If the solution does not conduct electricity, this crosses out ionic substance and metallic substance
If the solution does conduct electricity, this an ionic substance
Solubility
Melt the substance in water
If the substance dissolves, the substance is highly likely to be covalent molecular or ionic substance
If the substance does not melt this crosses out the covalent molecular
Hammering
Hammer the substances and observe whether their is a cut or is squashed
If there is a clean cut, there is a high chance that the substance is form by a network/lattice.
If the substance is squashed, it is mellable
Appearance under microscope
Observing the shape and how it physically looks like
A crystalline substance will be formed by a network/lattice
Risk assessment
goggles and aprons will be worn to protect our eyes and clothes
Fire mat will be used when fire is used
Substances that are physically dangerous will not be used to determine the type of structure it is created with
Appropriate equipment in the right way will be used to conduct each of the experiments
While testing the melting point, the test tube will be facing towards the opposite side of where the face is
Limitations
The melting point will not be exact and is approximated
Since the experiments are done at school by student, there will be a limit of resource and test students can utilise
While testing for conductivity in solution form, the substance may not dissolve in the water
The hammering experiment will be able to be conducted if the substance is in a state that is not in solid form or is too small to be observed
There are exceptions to the results of the experiments conducted such as graphite
While testing for conductivity in solid state, the substance needs to be in an appropriate size and not too small