6. Metals and Non-Metals Flashcards
element
pure substance made up of same type of atoms
Total no. of elements
118 (94 are natural)
Property of some large elements
they break down spontaneously as they are radioactive
Modern Periodic Table
arrangement of elements in tabular form to make studying elements easier
What gave rise to the Bronze age
making alloys of tin and copper (which have relatively low melting points)
what gave rise to the iron age
discovery that metals like iron and copper can be mass produced
smelting
process of extracting metals from their ore
ore
naturally occuring solid material from which a metal or valuable mineral can be extracted profitably
free state
existing as an element, not a compound
minerals
since metals usually donate ions and form cations they are very reactive and exist in nature as compounds called minerals
native form of metals
pure metallic form or alloys
Silver and coppers’ occurrence in nature
found in large amounts in their free states
Chromium, Titanium, Zinc, Iron, Tin, Cadmium, Nickel’s occurences in nature
- also sometimes occur in their free states due to natural chemical processes which reduce ore to metallic state
- found in smaller quantites
Potassium, sodium, calcium, magnesium, aluminium’s occurences in nature
highly reactive and only exist as minerals
where are majority of metals obtained from
Earth’s crust
Most abundant metal in Earth’s crust
Aluminium
Most abundant metal in sea water
Sodium (+Magnesium, Potassium, Calcium)
Non - metals
elements that accept electrons to form negatively charged ions (anions)
where are non-metals found
Earth’s atmosphere, crust, oceans
what non metal exists in both a free and combined state and how
- Oxygen
- exists as oxides of compounds (COMBINED)
- oxygen in the atmosphere exists in a free state
Most abundant non-metal in Earth’s crust
oxygen
most abundant non-metals in seawater
Chlorine + Bromine
Noble gases ()
- (exist only in their free state)
- Helium, Neon, Xenon, Krypton, Radon, Argon,
(NAHRKX)
Metalloids/ Semi-Metals
elements that exhibit properties that are in between those of metals and non-metals
(form a stair step line separating the metals from the non metals)
Metalloids (8)
Boron
Silicon
Germanium
Arsenic
Polonium
Antimony
Tellurium
Astatine
(SAPTA BAG)
Properties of metalloids 4
- all solids, brittle, dull/shiny
- usually malleable and ductile
- partial conductors of electricity
- Chemically they behave more like non metals BUT chemical behaviour depends on substance they are reacting with
Example of metalloid changing chemical behaviour
Ex - Boron with Sodium reacts like a non - metal
Boron with fluorine reacts like a metal
3 properties of noble gases
- colorless and odourless
- monoatomic
- all conduct electricity and fluoresce, i.e they emit a gloww
corrosion
slow destruction or damage of metals by chemical action
examples of oxidation reactions (3) where metal corrodes due to chemical reaction
rusting of iron
green coating on copper
blackening of silver
what makes noble metals different from other metals?
they do not generally corrode and retain their lustre even after several years
what is patina
- copper reacts with atmospheric gases in the presence of moisture and forms basic copper carbonate (CuCO3) and copper hydroxide [Cu(OH)2]
- this can be seen as a green deposit formed on copper articles and is called patina
what diminishes green tarnish on copper/patina
rubbing lemon/tamarind
formula for formation of green coating
Copper + Water + Carbon Dioxide + Oxygen - Copper Carbonate & Copper Hydroxide (Green deposit)
What does blackish brown copper oxide do?
sometimes copper corrodes and fors a layer of blackish brown copper oxide
this layer protects copper from further corrosion
How does aluminium react with air?
What is the property of aluminium oxide?
- forms layer of aluminium oxide on its surface
- this layer of Al2O3 prevents further corrosion of aluminium present under the surface
why does silver turn black after being exposed to air for a while
- due to reaction of silver and sulphur compounds present in the air and formation of silver sulphate
what color is silver sulphate (Ag2SO4)
black
rust (4 keywords)
pure iron reacts slowly with atmospheric oxygen to in the presence of moisture to form a brown compound known as rust
rusting
process of formation of rust
give two properties of rust [Iron (III) Oxide]
- soft and porous
- rust comes off easily and exposes inner pure iron to air for further rusting (hence this kind of corrosion leads to weakening of metal)
word reaction for Rust formation
Iron + Water + Oxygen - Hydrated ferric oxide (Rust)
What factors affect rusting of iron? (3+1)
- Water presence
- Exposure to air
- Condition of Iron
(if submerged in water, then Condition of Water)
is rust acidic or basic in nature?
Basic (red litmus paper turns blue, blue litmus paper stays the same)
what is fascinating about the iron pillar next to the Qutub Minar
7.2 metres tall and stands rust free even after 1600 years (prime evidence of ancient Indian chemical engineers who had advanced knowledge of rusting)
8 what are some ways of prevention of rust?
Oiling and greasing
Painting
Enamelling
Galvanisation
Tinning
Electroplating
Alloying
Anti - Rust solution
what two liquids are applied as paint to prevent contact with air on iron
Red Lead Oxide Paint
Tar ( thick black water resistant)
what is enamelling?
coating a mixture of ground glass, clay and water on iron at high temperatures
what is galvanisation
coating iron with a layer of zinc
what is the principle of galvanisation?
- zinc is more reactive than iron, so when in contact with air, it reacts first to form zinc oxide
- this protects the iron inside
why is galvanisation not used in food containers
- food materials are mostly acidic in nature
- react with zinc to produce a poisonous substance
- tinning is the most preferable method
two properties of tin which make it useful for tinning
- corrosion resistant metal (noble metal)
- non - toxic
how is the process of tinning carried out
- wrought iron sheets are dipped in molten tin and then used to make cans, boxes, etc
what happens in electroplating
- non- corrosive metals (tin, chromium, nickel) are made too form a thin coating on the iron object using electric current
- this also enhances look of the object
what act as anti - rust solutions?
Alkaline phosphates/ alkaline chromates
what happens when an iron article is boiled in anti-rust solution
film of iron phosphate/chromate is formed which protects it from rusting
general uses of metals 2
- due to their hardness and strength, they are used in construction of machinery, bridges, buildings
- metals are sonorous and hence used for making bells
3 general uses of iron
- biologically, iron in our blood carries oxygen around
- iron beams provide support for buildings
- iron is used to make parts for a variety of machinery
types of iron based on carbon content
wrought iron (less than 0.1% of carbon)
- soft and ductile
- railings, electromagnets, nails and bolts
pig iron (cast iron) - 2-4% of carbon
- drain pipes, manhole lids, sanitary fittings
steel 2% carbon
- high tensile strength
- rails, bridges, buildings, ships, automobiles, etc.
what is pig iron also called and why
cast iron
it easily forms cheap cast
what are gold and silver used for
- artificial teeth and filling teeth cavities
- used to make jewellery because they are SHINY
gold: thin films are used on satellites (temperature control) to reflect infrared radiation + mobile phones
silver: make electrodes and in electroplating
3 what is copper used for
- (good conductor) electrical transmission wires, coils of electric motors, generators
- utensils, coins, jewellery
- electroplated coating + pipes for plumbing
what is aluminium used for? 5
- foils and cans for food, beverages, utensils, doors, furniture
- electrical transmission wires (cheaper than copper)
- bodies of aircraft, automobiles, machine parts,
- being anti - corrosive, it is used in anti-rust paint
- very good reflector, used to make concave mirrors for astronomical telescopes
4 what is zinc used for
- boosts our immune system
- galvanisation of iron
- alloys such as brass and german silver
- extraction on metals
4 what is lead used for
- (heavy toxic metal) good absorber of radiation ( used in car batteries)
- protective shielding from X-rays and radioactive radiation
- alloys (solder and type metal)
- sanitary fittings ( does not react with impure water, or mild acids/alkalis)
what is magnesium used for
- helps in human metabolism
- used in fireworks since it produces a bright white dazzling light
- alloys used in aeroplanes and cars
use of tungsten
(highest melting point) used as filament in electric bulbs
use of sodium and pottasium
- make strong bases and used in the manufacture of soap and salts
use of calcium
- makes our bones and teeth strong
- used in alloys for special uses
use of mercury
- used as the liquid in thermometers
- used as an amalgam in dental fillings
use of platinum
- jewellery, electrodes, crucibles
- catalyst for many chemical processes
what is goitre and how is it caused
iodine deficiency
it is a prominent swelling in the front of the neck
what are general uses of metalloids 4
- making transistors, computer chips, and other electronic devices
- metalloids are used to make glass
- used with metals to make alloys as they add strength
- make heat and flame resistant objects
what is boron used for
binding agents in magents
what is silicon used for
- makes silicon chips
- makes silicone which has various uses
- silicon dioxide is useful for domestic glassware
what is antimony used for?
- batteries, bullets, lead shots, musical instruments
what is germanium used for?
transistors and thermal imaging cameras
