Is Matter Around Us Pure
Introduction
• Matter around us is not all pure
• Sugar (uniform particles) = pure substance
• Soil (mixed particles) = impure substance (mixture)
• Matter is of two types: Pure Substances and Mixtures
Pure Substances: Elements and Compounds
• Made up of only one kind of particle (atoms or molecules)
• Homogeneous throughout its mass
• Has fixed composition, fixed melting point and boiling point
• Cannot be separated by physical processes
• Examples: water, sulphur, hydrogen, oxygen, sodium chloride, sugar, carbon
dioxide, copper sulphate, calcium oxide, sodium hydroxide, hydrochloric acid,
sulphuric acid, nitric acid, camphor, naphthalene, sand
Impure Substances: Mixtures
• Contains two or more different kinds of particles
• Can be separated by physical processes
• No fixed composition, no fixed melting/boiling point
• May be homogeneous or heterogeneous
• Examples: salt solution, sugar solution, milk, sea-water, air, sugarcane juice,
soft drinks, rocks, petroleum, LPG, biogas, tap water, tea, coffee, paint, wood,
soil, bricks
Elements
Definition: A substance that cannot be split into two or more simpler substances by
usual chemical methods (heat, light, electric energy).
• Made of only one kind of atom
• All atoms of an element are identical
• Atoms of different elements differ in size and composition
, • 115 elements known; 92 occur in nature, 23 are artificially prepared
• Each element has a separate symbol
Common Elements: Hydrogen, Helium, Oxygen, Nitrogen, Carbon, Sulphur,
Phosphorus, Chlorine, Bromine, Iodine, Sodium, Potassium, Magnesium, Calcium,
Aluminium, Copper, Silver, Gold, Zinc, Iron, Silicon, Tin, Mercury
Diamond and graphite are allotropic forms of carbon element.
States of Elements
• Most elements are solids
• 11 elements are gases
• Only 2 elements are liquids at room temperature: Mercury and Bromine
Metals, Non-Metals and Metalloids
Elements are divided into 3 groups based on properties:
A. METALS
Definition: An element that is malleable, ductile, and conducts electricity.
Examples: Iron, Copper, Aluminium, Zinc, Silver, Gold, Platinum, Chromium, Sodium,
Potassium, Magnesium, Nickel, Cobalt, Tin, Lead, Cadmium, Mercury, Antimony,
Tungsten, Manganese, Uranium
All metals are solids except Mercury, which is a liquid.
Properties of Metals
# Property Description
1 Malleable Can be beaten into thin sheets without breaking. Best:
Gold, Silver, Aluminium, Copper
2 Ductile Can be drawn into thin wires. Best: Gold, Silver. 100
mg silver → 200 m wire
3 Good Conductors of Best conductor: Silver. Next: Copper, Gold,
Heat & Electricity Aluminium, Tungsten. Poorest: Lead, Mercury
4 Lustrous (Shiny) Can be polished. Property called metallic lustre
(chamak). Silver is best reflector of light
, 5 Generally Hard Exceptions: Sodium & Potassium are soft (can be cut
with knife)
6 High Tensile Strength Can hold large weights. Iron (steel) used in bridges,
buildings, railways
Important Applications
• Aluminium foil → packing food, medicines, chocolates, cigarettes
• Cooking utensils & water boilers → copper/aluminium (good heat conductors)
• Electric wires → copper and aluminium (good electrical conductors)
• Jewellery → gold and silver (shiny and lustrous)
• Construction → iron/steel (high tensile strength)
More Properties of Metals (continued)
# Property Details
7 Solids at All metals are solids except Mercury (only liquid metal)
Room
Temperature
8 High Melting Iron melts at 1535°C, Copper at 1083°C. Exceptions: Sodium &
& Boiling Potassium have low melting points (<100°C). Gallium melts in
Points hand
9 High Metals are heavy. Iron density = 7.8 g/cm³. Exception: Sodium &
Densities Potassium have low densities
10 Sonorous Make ringing sound when struck → used for bells, cymbals
(manjira), strings of violin, guitar, sitar, tanpoora
11 Silver or Exceptions: Copper (reddish-brown), Gold (yellow)
Grey Colour
B. NON-METALS
Definition: An element that is neither malleable nor ductile, and does not conduct
electricity.
Examples: Carbon, Sulphur, Phosphorus, Hydrogen, Oxygen, Nitrogen, Fluorine,
Chlorine, Bromine, Iodine, Helium, Neon, Argon, Krypton, Xenon, Diamond, Graphite
Diamond and Graphite are allotropic forms of carbon — they are also non-metals. All
non-metals are solids or gases except Bromine, which is the only liquid non-metal at
room temperature.
Introduction
• Matter around us is not all pure
• Sugar (uniform particles) = pure substance
• Soil (mixed particles) = impure substance (mixture)
• Matter is of two types: Pure Substances and Mixtures
Pure Substances: Elements and Compounds
• Made up of only one kind of particle (atoms or molecules)
• Homogeneous throughout its mass
• Has fixed composition, fixed melting point and boiling point
• Cannot be separated by physical processes
• Examples: water, sulphur, hydrogen, oxygen, sodium chloride, sugar, carbon
dioxide, copper sulphate, calcium oxide, sodium hydroxide, hydrochloric acid,
sulphuric acid, nitric acid, camphor, naphthalene, sand
Impure Substances: Mixtures
• Contains two or more different kinds of particles
• Can be separated by physical processes
• No fixed composition, no fixed melting/boiling point
• May be homogeneous or heterogeneous
• Examples: salt solution, sugar solution, milk, sea-water, air, sugarcane juice,
soft drinks, rocks, petroleum, LPG, biogas, tap water, tea, coffee, paint, wood,
soil, bricks
Elements
Definition: A substance that cannot be split into two or more simpler substances by
usual chemical methods (heat, light, electric energy).
• Made of only one kind of atom
• All atoms of an element are identical
• Atoms of different elements differ in size and composition
, • 115 elements known; 92 occur in nature, 23 are artificially prepared
• Each element has a separate symbol
Common Elements: Hydrogen, Helium, Oxygen, Nitrogen, Carbon, Sulphur,
Phosphorus, Chlorine, Bromine, Iodine, Sodium, Potassium, Magnesium, Calcium,
Aluminium, Copper, Silver, Gold, Zinc, Iron, Silicon, Tin, Mercury
Diamond and graphite are allotropic forms of carbon element.
States of Elements
• Most elements are solids
• 11 elements are gases
• Only 2 elements are liquids at room temperature: Mercury and Bromine
Metals, Non-Metals and Metalloids
Elements are divided into 3 groups based on properties:
A. METALS
Definition: An element that is malleable, ductile, and conducts electricity.
Examples: Iron, Copper, Aluminium, Zinc, Silver, Gold, Platinum, Chromium, Sodium,
Potassium, Magnesium, Nickel, Cobalt, Tin, Lead, Cadmium, Mercury, Antimony,
Tungsten, Manganese, Uranium
All metals are solids except Mercury, which is a liquid.
Properties of Metals
# Property Description
1 Malleable Can be beaten into thin sheets without breaking. Best:
Gold, Silver, Aluminium, Copper
2 Ductile Can be drawn into thin wires. Best: Gold, Silver. 100
mg silver → 200 m wire
3 Good Conductors of Best conductor: Silver. Next: Copper, Gold,
Heat & Electricity Aluminium, Tungsten. Poorest: Lead, Mercury
4 Lustrous (Shiny) Can be polished. Property called metallic lustre
(chamak). Silver is best reflector of light
, 5 Generally Hard Exceptions: Sodium & Potassium are soft (can be cut
with knife)
6 High Tensile Strength Can hold large weights. Iron (steel) used in bridges,
buildings, railways
Important Applications
• Aluminium foil → packing food, medicines, chocolates, cigarettes
• Cooking utensils & water boilers → copper/aluminium (good heat conductors)
• Electric wires → copper and aluminium (good electrical conductors)
• Jewellery → gold and silver (shiny and lustrous)
• Construction → iron/steel (high tensile strength)
More Properties of Metals (continued)
# Property Details
7 Solids at All metals are solids except Mercury (only liquid metal)
Room
Temperature
8 High Melting Iron melts at 1535°C, Copper at 1083°C. Exceptions: Sodium &
& Boiling Potassium have low melting points (<100°C). Gallium melts in
Points hand
9 High Metals are heavy. Iron density = 7.8 g/cm³. Exception: Sodium &
Densities Potassium have low densities
10 Sonorous Make ringing sound when struck → used for bells, cymbals
(manjira), strings of violin, guitar, sitar, tanpoora
11 Silver or Exceptions: Copper (reddish-brown), Gold (yellow)
Grey Colour
B. NON-METALS
Definition: An element that is neither malleable nor ductile, and does not conduct
electricity.
Examples: Carbon, Sulphur, Phosphorus, Hydrogen, Oxygen, Nitrogen, Fluorine,
Chlorine, Bromine, Iodine, Helium, Neon, Argon, Krypton, Xenon, Diamond, Graphite
Diamond and Graphite are allotropic forms of carbon — they are also non-metals. All
non-metals are solids or gases except Bromine, which is the only liquid non-metal at
room temperature.
