Pure Substances and Mixtures

​Pure Substances and Mixtures

​TEKS 6.5A

​I am learning about how an element is a pure substance represented by a chemical symbol and that a compound is a pure substance represented by a chemical formula.

​Essential Question: Are both elements and compounds pure substances?

Melting, freezing, cutting, smashing do not change the identity of a substance​.

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Cannot Be Formed or Broken Down by Physical Changes​

​All elements are considered a pure substance and have definite physical and chemical properties.

Examples- Sodium (Na) or Gold​

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​Made up of One Type of Particle

​Pure Substances

Compounds such as water are a pure substance as well. ​

​Vocabulary Word

​Molecule

Are atoms bonded together, representing the smallest number of fundamental unit in a chemical compound.

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Example- ​Water (H₂0) is considered a molecule

​Methane (CH₄) gas is a molecule

​The next question is a DOL

Do not worry if you get it wrong!​

Multiple Choice

Which of these common mixtures is a homogenous mixtures?

• table salt

• pure water

• whole milk

• maple syrup

Open Ended

What happens when a pure substance undergoes chemical change?

​Classification of Compounds

​How they are Classified

• pH Scale​ this means it can be classified as acidic, basic, or neutral.

• Organic vs Inorganic (organic simply means it contains a carbon) Organic compounds that are made by living things called Biochemicals. Biochemicals are carbohydrates, lipids, proteins, and nucleic acids.

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​Classification of Elements

​How they are classsified

Elements are arranged on the periodic table ​by both chemical and physical properties.

They are arranged on the periodic table as: metal, nonmetal, or metalloids.​

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Are substances that are evenly spread throughout a mixture. ​

​An example would be sugar water.

​Homogenous Mixture

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​Is a mixture that does not have a uniform or even composition.

​Pizza would be a delicious example of a heterogenous mixture!

Heterogenous Mixtures​