Chemistry teacher

Metals and Non-Metals – Notes 1. Introduction There are 115 known chemical elements . Elements show similarities and differences in their properties. On the basis of properties, elements are classified into: (a) Metals (b) Non-Metals 2. Important Terms Malleable → can be hammered into thin sheets. Ductile → can be drawn into thin wires. Brittle → breaks easily when hammered or stretched. 3. Metals Definition : Metals are elements that: Conduct heat and electricity Are malleable and ductile Form positive ions by losing electrons (electropositive). General Properties of Metals : Good conductors of heat and electricity Malleable and ductile Lustrous (shiny) Hard, strong, heavy Sonorous (produce ringing sound) Mostly solids (except mercury which is liquid) Examples : Iron, Aluminium, Copper, Silver, Gold, Platinum, Zinc, Sodium, Potassium, Calcium, Magnesium. Abundance in Earth’s Crust : Aluminium (7%) → most abundant metal Iron (4%) Others: ...

Acids, Bases and Salts – Notes Introduction There are about 115 known chemical elements . They combine to form thousands of compounds . Based on chemical properties, compounds are mainly classified into: Acids Bases Salts To identify acids and bases, we use indicators . Indicators An indicator is a dye that changes colour in acidic or basic solutions. 1. Litmus (Natural Indicator) Extracted from lichens . Neutral colour = Purple . Available as red litmus and blue litmus . Reactions: Acid → Turns blue litmus red . Base → Turns red litmus blue . Examples: Orange juice turns blue litmus → red → Acidic. NaOH solution turns red litmus → blue → Basic. 👉 Note: Water-soluble bases are called alkalis . 2. Methyl Orange (Synthetic Indicator) Neutral colour = Orange . Acid → Red Base → Yellow 3. Phenolphthalein (Synthetic Indicator) Neutral colour = Colourless . Acid → Colourless Base → Pink 4. Universal Indicator A mixture of indicators....