Lesson Notes By Weeks and Term v4 - JHS 3
MATERIALS
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MATERIALS
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Subject: Science
Class: JHS 3
Term: 1st Term
Week: 2
Grade code: B9.1.1.1.2
Strand code: 1
Sub-strand code: 1
Content standard code: B9.1.1.1
Indicator code: B9.1.1.1.2
Theme: DIVERSITY OF MATTER
Subtheme: MATERIALS
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Materials around us (water we drink, salt in our food, rust on iron roofing sheets, limestone used for cement, gases in car exhaust) are made of elements and compounds. Many common compounds in Ghana are binary compounds—compounds made from only two different elements. Understanding how binary compounds form helps learners explain everyday phenomena such as corrosion (rusting), burning of fuels, salt formation, and why some substances conduct electricity while others do not.
A. Distinguishing: Element, Molecule, Ion, Compound 1) Element A pure substance made of only one type of atom. Examples: Fe (iron), O (oxygen), C (carbon), Mg (magnesium), Cl (chlorine). 2) Molecule Two or more atoms chemically bonded together as a neutral particle. Can be of the same element or different elements. Examples: O₂ (oxygen molecule) – same element H₂O (water molecule) – different elements 3) Ion An atom or group of atoms that has gained or lost electrons, so it has a charge. Cation: positive ion (lost electrons), e.g., Na⁺, Mg²⁺, Fe²⁺ Anion: negative ion (gained electrons), e.g., Cl⁻, O²⁻, S²⁻ 4) Compound A substance made when two or more different elements combine chemically in a fixed ratio. Examples: NaCl, H₂O, CO₂, MgO, FeS
> Binary compound: a compound made of exactly two different elements. Examples: NaCl (Na + Cl), MgO (Mg + O), CO₂ (C + O), FeS (Fe + S), H₂O (H + O)
B. How Binary Compounds Form (Main Indicator Focus)
Binary compounds form mainly in two ways: 1) Ionic Bonding (Electron Transfer) → Ionic Binary Compounds Usually between a metal and a non-metal. The metal loses electrons to form a positive ion. The non-metal gains electrons to form a negative ion. The opposite charges attract to form an ionic compound. Example 1: Formation of Sodium Chloride (NaCl) Sodium (Na) is a metal with 1 valence electron. Chlorine (Cl) is a non-metal needing 1 electron to complete its outer shell.