Lesson Notes By Weeks and Term v4 - SHS 3
MATTER AND ITS PROPERTIES
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MATTER AND ITS PROPERTIES
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Subject: Chemistry
Class: SHS 3
Term: 1st Term
Week: 15
Grade code: 1.1.1.LI.6
Strand code: 1
Sub-strand code: 1
Content standard code: 1.1.1.CS.2
Indicator code: 1.1.1.LI.6
Theme: PHYSICAL CHEMISTRY
Subtheme: MATTER AND ITS PROPERTIES
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This series of lessons forms the foundation of chemical communication. Just like we use grammar to form correct sentences in English, chemists use a set of universal rules to name compounds, write their formulas, and describe their reactions. This ensures that a chemist in Accra, a pharmacist in Kumasi, or a researcher in Bolgatanga are all speaking the same scientific language. Understanding these rules is essential for everything from reading the label on a fertilizer bag to understanding how medications work, or how our industries like VALCO operate.
This topic can be broken down into three main areas: the laws governing combinations, the language for naming and writing formulae, and the syntax for writing chemical reactions. Part A: The Laws of Chemical Combination
These are the fundamental principles that matter follows when it undergoes chemical change. Law of Conservation of Mass: Statement: In any closed system, mass is neither created nor destroyed during a chemical reaction. The total mass of the reactants must equal the total mass of the products. Explanation: Think of it like building with LEGO blocks. If you start with 10 red blocks and 5 blue blocks, you can build different structures, but you will always end up with a total of 15 blocks. In chemistry, atoms are just rearranged, not lost or gained. This is the very reason we must balance chemical equations. Example: When charcoal (carbon) burns completely in air, it forms carbon dioxide. `C(s) + O₂(g) → CO₂(g)` If you start with 12g of Carbon and it reacts completely with 32g of Oxygen, you will produce exactly 12g + 32g = 44g of Carbon Dioxide. Law of Definite (or Constant) Proportions: Statement: A given chemical compound always contains its component elements in a fixed ratio by mass, regardless of its source or method of preparation. Explanation: Pure water (H₂O) is always 88.9% oxygen and 11.1% hydrogen by mass. It doesn't matter if the water comes from the Weija Dam, a borehole in Tamale, or is made in a laboratory. The ratio is constant.