Chapter Notes and Summary
• Objects around us can be made up of one or more materials.
• Different materials have different properties and they are grouped on basis of differences and similarities in their properties.
• systematic arrangement of things on basis of certain similarities or difference is called sorting.
• Things can be grouped on basis of material they are made of.
• Matter is any thing that has mass and occupies space.
• An atom is smallest indivisible particle of matter.
• An element is a substance made of same type of atoms.
• A compound is a substance made of different types of elements.
• Some materials are lustrous or shiny in appearance (e.g., metals) and some are not (e.g., chalk, wood and paper).
• Some materials are soft (e.g., candle and chalk) and some are hard (e.g., metals and wood).
• materials that can be compressed are called soft.
• materials that can not be compressed are called hard .
• feel of any material is called its texture.
• Substances that completely dissolve in water are called soluble substances. e.g., sugar, salt, lemon juice etc.
• Substances that do not dissolve in water are called insoluble substances. e.g., sand, chalk powder, dust, kerosene etc.
• Substances through which things can be seen are called transparent substances. e.g., glass, water and air.
• Substances through which things can be seen but not clearly are called translucent substances. e.g., oiled paper, muslin cloth etc.
• Materials through which things can not be seen are called opaque substances e.g., wood, metals etc.
• Materials can be grouped on basis of their solubility in water.
• Liquids that mix with each other are called miscible liquids and which do not mix with each other are called immiscible liquids.
• Density of a substance is defined as mass per unit volume.
• Metals are good conductors of heat and electricity.
• Materials can be grouped as solids, liquids or gases according to physical state in which they exist.