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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?
What is a chemical substance?
A chemical substance is a form of matter that has a definite chemical composition. They are composed of one or more atoms that are bonded together. There are different forms of chemical substances such as elements and compounds.
Nature of substance
Metallic/Nonmetallic
Describe the shapes
linear
triagonal planar
tetrahedral
bent
triagonal pyramidial
Bonding
Ionic, covalent, metallic
Freezing, melting and boiling point
bunsen burner
Temperature
periodic table
Groups and Periods
Compounds, mixtures, elements
Limitations
Limitation of resources, there may not be a method that is available in the lab.
Not having the right resources limit the amount of methods that can be tested, therefore during the practical the "best" method to identify a chemical substance may not be found
Ethical consideration, if the chemical substance plays a significant role in society to a point where it shouldn't be used for an experiment
Evolving knowledge, change of information due to new data. New information could possibly reveal unknown knowledge on a substance's properties.
Complexity of each chemical substance, not all substances may suit the methods that are prepared. Examples such as incomplete octect and expansion of octect
Limited time can create a sense of rush during the pracitcal, therefore not letting the experimenter do their best potential. Another reason that lack of time can be a limitation is because not all methods may be able to be tested during the lesson time.
Risk Assessments
Using a bunsen burner to test the melting point can be dangerous, wear safety gear and use the right procedures to use a bunsen burner
Toxic Substances, can go into open wounds, eyes and exposed areas which could cause serious harm to the human body
Glass breaking, therefore be careful with glass, always make sure to wear proper gear
Spilling and leaking of chemical substances, someone may slip if you spill a liquid on the floor
Background Information
Ionic compounds is a substance that has a combination of metallic and non-metallic elements to create a stronger. They tend to form when a metal reacts with a non-metal so that the metallic element is able to lose an electron, turning it into a cation. Most rocks, gemstones and minerals are ionic compounds as an ionic compound will be stronger than one raw element.
A chemical bond is the force of attraction that holds atoms together which are formed by the interaction of valence electrons. They are responsible for stability and structure of compounds and molecules in a chemical substance. There are three primary chemical bonding, ionic, covalent and metallic bonding.
Ionic Bonding
Most atoms prefer to have 8 valance electrons so that its more stable, so they prefer to lose or gain electrons. When cations and anions are next to each other, they attract to each other
Dissolving in water, high melting point (1,800 Celcisu is considered high melting point), hard/brittle, electrical conductivity are all methods to test if they are ways to see if they have ionic bonding
If the substance is a solid, dissolving it in water can show that it has an ionic or polar covalent bond.
By using a bunsen burner to melt the substance can be another method. Substances with ionic bonds tend to have a high melting point, therefore measuring the substance to see if melted at a high temperature can be an effective way to test to see if it has an ionic bond.
By touching the substance, if it is hard or brittle the substance may have an ionic bond. This can be a way to test it.
By using a conductivity measurer, we can see if the substance has an ionic bond. Substances with ionic bonds will be able to conduct electricity therefore making it another effective way to test it.
Covalent Bonding
Covalent bonding is formed between non-metals. The atoms become stable by sharing electrons with neighbouring atoms rather than transferring.
Doesn't dissolve in water, not solid at room temperature, doesn't conduct electricity in any form, low melting point (233 Celcius considered low melting point) are ways to test if they have a covalent bonding
Attempting to dissolve it in water can be a great way to see if the substance has a covalent bond because substances with covalent bonds do not dissolve.
By just looking it at the substance at room temperature can tell us if it has covalent bonds or not. Substances with covlaent bonds are not solid at room temperature.
By using a conductivity measurer, if the substance does not conduct electricity then it has covalent bonding. If it does conduct electricity then it will have ionic bonds.
By using a bunsen burner to see if the substance melts at a low temperature. Substances with covalent bonds have a low melting point therefore it will show us if it has covalent bonds or not.
Metallic Bonding
Metallic bonding is formed between metals. They tend to lose electrons rather tha gaining, therefore the electrons that are removed are no longer bound to the atom and are able to move around freely.
High melting point, malleable, lustrous, ductile, thermal conductor are ways to test out if a substance has metallic bonding
By using a bunsen burner, to see if it has a high melting point as substances with metallic bonds have a high melting point
By looking at it, if the substance is lustrous and is shiny, it may be a substance with metallic bonding.
Using a conductivity tester can allow experimenters to see if the substance has a metallic bonding or ionic bonding.
By touching the substance, if the substance is ductile and malleable then the substance most likley has metallic bonds.
Factors that effect the methods to classify a chemical substance?
Physical property, whether if its a solid, liquid or gas at room temperature
Environment, the temperature of the room, any possible toxins around the room (cross contamination)
Toxcidity of the substance, if the substance is too toxic for usage then it would be most ethical to not use it as the experimenter can get put in a dangerous position.
What are some “categories” of chemical substances?
Elements
A pure element is a chemical substance that is composed of one single type of atom. Elements are on the perodic table.
Compounds
Chemical substances that are composed of two ore more types of atoms. They are held by bonds such as ionic, covalent and metallic. They are formed together to create compounds such as H2O which consists of two parts hydrogen and one part oxygen.
Mixtures
Mixtures are substances that can contain both elements and compounds. They are not held together by bonds. An example of a mixture is air, which is composed of elements and compounds but are not bonded together.
Gas, solid, liquid
Chemical substances are able to exist in different states of matter, gas, liquid and solid. There are ways to switch a substance from on matter to another such as evaporating a liquid into a gas and freezing a liquid to a solid and vice versa. In order to complete the method of evaporation to test if the substance is an ionic bond, the substance would have to be a solid that is mixed with a liquid.
Acids and Bases
Acids and Bases are based on a substance's ph level. If it is high then it is an acid and if it is relatively low, then it is a base. Some everyday examples of acids are lemons, oranges or any citrus fruits. Some examples of bases is water and soap.
Minerals
Minerals are compounds or elements that occur naturally. Some examples are quartz, diamonds and sulfur.
Nanomaterials
Substances that have a structure and property at a nanoscale. Some examples are nanotubes.
Solutions
Solutions are when a substance (solute) is dissolved in another substance (solvent), one common example would be salt dissolved in water, which can be used to test out if a substance has an ionic bond.