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Chemical compounds and elements
A topic from the subject of Standardization in Chemistry.
Chemical Compounds and Elements
Elements are the basic building blocks of matter. They cannot be broken down into simpler substances by chemical means. Each element has a unique symbol, such as H for hydrogen, O for oxygen, and Fe for iron.
Compounds are substances that are made up of two or more elements that are chemically combined. The elements in a compound are held together by chemical bonds, which are forces that attract atoms to each other. Compounds have different properties from the elements that they are made of.
Key Points
- Elements are the fundamental units of matter.
- Compounds are substances that are made up of two or more elements.
- Chemical bonds hold the elements in a compound together.
- Compounds have different properties from the elements that they are made of.
Main Concepts
- Atomic number: The atomic number is the number of protons in the nucleus of an atom. It is a unique identifier for each element.
- Mass number: The mass number is the total number of protons and neutrons in the nucleus of an atom.
- Chemical bond: A chemical bond is a force that attracts atoms to each other. There are different types of chemical bonds, such as ionic bonds, covalent bonds, and metallic bonds.
- Molecular formula: The molecular formula of a compound shows the number of each type of atom in the compound.
Experiment: Separating Elements and Compounds
Materials
- Salt (sodium chloride)- Sand (silicon dioxide)
- Water
- Filter paper
- Funnel
- Graduated cylinder
- Beaker
Procedure
1. Measure 100 mL of water into the graduated cylinder.2. Add 10 grams of salt to the water and stir until dissolved.
3. Add 10 grams of sand to the water and stir.
4. Pour the mixture through the funnel lined with filter paper.
5. The sand will be trapped on the filter paper, while the water and salt will pass through.
6. Rinse the filter paper with water to remove any remaining salt.
7. Dry the filter paper and sand.
Observations
- The sand is trapped on the filter paper, while the water and salt pass through.- The filter paper is white after it has been dried.
- The sand is still brown after it has been dried.
Conclusion
- The experiment shows that salt and sand are different substances.- Salt is soluble in water, while sand is not.
- This experiment can be used to separate other mixtures of elements and compounds.
Significance
- This experiment is a simple way to demonstrate the difference between elements and compounds.- It can be used to teach students about the properties of different substances.
- It can also be used to separate mixtures of different substances.