Comprehensive Notes on Metals and Non-metals

Metals and Non-metals

A metal is a chemical element that is a good conductor of both electricity and heat.
Metals form ionic bonds with non-metals.
In a metal, atoms readily lose electrons to form positive ions (cations).
These ions are surrounded by electrons and are not bound to any specific atom. This is responsible for the conductivity.
The solid thus produced is held by electrostatic interactions between the ions and the electron cloud, which are called metallic bonds.
Metals occupy the bulk of the periodic table.
Non-metallic elements can only be found on the right-hand side of the Periodic Table of the Elements.
Metals are usually inclined to form cations (positive ions) through electron loss.
Metals react with oxygen in the air to form oxides over changing timescales (iron rusts over years, while potassium burns in seconds).
Examples:
- 4 Na + O2 \rightarrow 2 Na2O (sodium oxide)
- 2 Ca + O2 \rightarrow 2 CaO (calcium oxide)
- 4 Al + 3 O2 \rightarrow 2 Al2O3 (aluminium oxide)
The transition metals (such as iron, copper, zinc, and nickel) take much longer to oxidize.
Others, like palladium, platinum, and gold, do not react with the atmosphere at all.
Some metals form a barrier layer of oxide on their surface which cannot be penetrated by further oxygen molecules and thus retain their shiny appearance and good conductivity for many decades (like aluminum, magnesium, some steels, and titanium).
The oxides of metals are generally basic.
Chromic oxide Cr2O3 and metalloid antimony oxide (Sb2O3) are acidic.
Some metals like Zinc (Zn) and Aluminum (Al) form amphoteric oxides, which react with acids as well as alkalis.
- Al2O3 + 6HCl \rightarrow 2AlCl3 + 3H2O (reaction with acid)
- Al2O3 + 2NaOH \rightarrow Na2Al2O4 + H2O (reaction with base)
Oxides of nonmetals usually are acidic. Example: SO2, NO2, CO2.
Some nonmetals form neutral oxides (CO, NO, N2O, H2O).
Metals in general have:
- High electrical conductivity
- Thermal conductivity
- Luster
- Density
- The ability to be deformed under stress without breaking
The majority of metals have higher densities than the majority of nonmetals.
There is wide variation in the densities of metals; lithium is the least dense solid element and osmium is the densest.
The high density of most metals is due to the tightly packed crystal lattice of the metallic structure.
Descending order of density: Osmium, iridium, platinum, gold, mercury, lead, silver, copper, brass, iron, tin, zinc, cast iron, aluminum, marble, granite, glass.
Metals are ductile (They can be drawn into wires).
Metals also have Malleability (Means they can be transformed into sheets).
Non-metals are very few in number (only 18).
They are poor conductors of heat and electricity when compared to metals.
They form acidic oxides (whereas metals generally form basic oxides).
In solid form, they are dull and brittle, rather than metals which are lustrous, ductile, or malleable.
Usually non-metals have lower densities than metals.
They have significantly lower melting points and boiling points than metals (with the exception of Carbon).
Nonmetals make up most of the crust, atmosphere, and oceans of the earth.
Bulk tissues of living organisms are composed almost entirely of nonmetals.
Most nonmetals are monatomic noble gases or form diatomic molecules (like O2, N2) in their elemental state.
Metals do not form such molecules in the element stage. They form a crystalline structure.

Important Points About Metals and Non-metals

Silver reacts with sulfur, forming black silver sulfide. Hence, silver articles turn black if they come into contact with eggs or are kept open in the air.
Mercury is a liquid metal. Gallium, cesium, and rubidium are liquid metals at room temperature. Bromine is a liquid non-metal.
Mercury can dissolve gold and form an amalgam.
Cooking vessels are made up of metals as they are good conductors of heat. Copper and brass vessels are tinned (a thin layer of tin is applied) because they form toxic substances after reacting with acids.
Aqua regia is a mixture of HCl : HNO3 (3:1). Gold and platinum can be dissolved into it.
Most abundant metal on earth's crust – aluminum and iron.
Most abundant non-metal – oxygen and silicon.
Reactivity series in decreasing order – K, Na, Ca, Mg, Al, Zn, Fe, Pb, (H), Cu, Ag, Pt, Au.
Uranium, thorium, and plutonium are used in atomic furnaces to get energy. They are radioactive elements, emitting alpha, beta, and gamma rays.
Radium was discovered from ores of pitchblende by Madam Curie.
Titanium compounds are used in paints. A tin and lead alloy is used for soldering.

Chemical Properties

Reaction of Metals with Acids like HCl / H2SO4

Metals K, Na - Explosive reaction even with dilute acids, liberating H2
- K + 2HCl \rightarrow 2KCl + H2 \uparrow
Metals (Ca, Mg, Al, Zn, Fe) – with dilute acids, the reaction is less vigorous; H2 is liberated with decreasing vigor for the metals in sequence.
- Ca + 2HCl \rightarrow CaCl2 + H2 \uparrow
- Mg + H2SO4 \rightarrow MgSO4 + H2 \uparrow
- 2Al + 6HCl \rightarrow 2AlCl3 + 3H2 \uparrow
- Zn + H2SO4 \rightarrow ZnSO4 + H2 \uparrow
- Fe + H2SO4 \rightarrow FeSO4 + H2 \uparrow
Metals (Pb, Cu, Hg, Ag): No action with dilute acids. Only Pb reacts with concentrated HCl.
- Pb + [conc] HCl \rightarrow PbCl2 + H2 \uparrow
Metals Platinum (Pt) and Gold (Au) don’t react even with concentrated acids.

Reaction with Water

K, Na, Ca react with cold water to release H2 and form hydroxides.
- 2Na + 2H2O \rightarrow 2NaOH + H2 \uparrow
Mg reacts with water only if it is heated with steam. It releases H2 and forms oxide.
- Mg + H2O \rightarrow MgO + H2 \uparrow
Aluminum shows no reaction with water.
Fe has a reversible reaction with water.
- 3Fe + 4H2O \rightarrow Fe3O4 + 4H2\uparrow
Pb, Cu do not react with water or steam.

Rusting of Iron (in presence of oxygen and water)

4Fe + 3O2 + H2O \rightarrow 2Fe2O3 . nH2O (rusting is faster if water contains acids or electrolytes or if iron is impure).

Reduction of Metal Oxides

Many metals are found in the form of oxides. They are reduced to obtain pure metals.
Coke is a preferred reducing agent as it is widely available and cheap.
Other reducing agents are carbon monoxide and hydrogen.
Highly reactive metals like K, Na, Ca, Mg, Al cannot be reduced by using such agents.

Examples:
- Fe2O3 + 3CO \rightarrow 2Fe + 3CO2 \uparrow
- PbO + C \rightarrow Pb + CO \uparrow
- ZnO + C \rightarrow Zn + CO \uparrow
- CuO + H2 \rightarrow Cu + H2O \uparrow
Less reactive metals can be reduced by thermal decomposition
- 2HgO \rightarrow 2Hg + O2 \uparrow
- 2Ag2O \rightarrow 4Ag + O2 \uparrow
Pt, Au do not form oxides.

Properties of Hydroxides, Carbonates, Nitrates

Metal	Carbonate in water	Carbonate when heated	Hydroxide in water	Hydroxide when heated	Metal nitrate
K	Soluble	Stable to heat	Soluble	Stable to heat	Nitrate + O2 \newline 2KNO3 \rightarrow2KNO2 + O2\uparrow
Na	Soluble	Stable to heat	Soluble	Stable to heat
Ca	Insoluble	CaCO3\rightarrow CaO+C O2\uparrow	Soluble	Ca(OH)2\rightarrow CaO + H2O\uparrow
Mg	Insoluble	Insoluble
Al	Insoluble	Carbonate→oxide + carbon dioxide	Insoluble		Nitrate → oxide + O2 + NO2
Zn, Fe	Insoluble
Pb	Insoluble				2Pb(NO3)2 \rightarrow 2PbO + 4NO2 + O
Cu	Insoluble
Hg	Insoluble
Ag	Insoluble	Metal + O2 + CO2
Pt, Au	Don’t form	Don’t form	Don’t form

Metal Oxides

Zincite (ZnO)
Hematite (Fe2O3)
Bauxite (Al2O3.2H2O)
Cuprite (Cu2O)

Carbonates

Marble (CaCO3)
Calamine (ZnCO3)
Siderite (FeCO3)
Magnesite (MgCO3)

Halides

Fluorspar (CuF2)
Cryolite (Na3AlF6)
Horn silver (AgCl)
Rock salt (NaCl)

Sulphides

Zinc blende (ZnS)
Galena (PbS)
Iron pyrite (FeS2)
Cinnabar (HgS)

Sulphates

Anglesite (PbSO4)
Barite (BaSO4)
Gypsum (CaSO4.2H2O)
Epsom salt (MgSO4.7H2O)

Metallurgy

Metallurgy is a material science that studies the physical and chemical properties of metals.
Extraction of metals from their ores is also studied under metallurgy.
The compounds of various metals found in nature associated with their earthly impurities are called minerals.
The naturally occurring minerals from which metals can be extracted profitably and conveniently are called metal ores.
The rocky impurities associated with ore (like silica SiO2) are called ‘matrix’ or ‘gangue’.
Some chemicals, called flux, are added to get rid of earthly impurities. Due to flux, impurities get converted into a ‘slag’ which can be separated from pure metal easily.
For extraction of metal form the impure ore first the soil impurities are removed. This is called concentration of the ore.
Then the ore is treated in a suitable way to obtain pure metal.

Concentration of the Ore

This method is used to remove the impurities, mud, silica from the ore.
This increases the concentration of the required compound.

Methods to Achieve Concentration

Electromagnetic process
- This method is useful to separate magnetic ore from non-magnetic gangue.
- Pulverized (crushed to small pieces) ore is put on a conveyor belt.
- The magnetic particles are attracted to the magnetic wheel and fall separately apart from non-magnetic particles.
- This is a cheaper and faster method for magnetic metals like iron.
Froth floatation process
- This process separates ore and gangue by preferential wetting.
- It is useful for those metals whose ore is preferentially wetted by oil and gangue is preferentially wetted by water.
- This method is generally useful for sulfide ores.
- The ore is taken in a large tank containing oil and water.
- It is agitated with compressed air.
- The ore is wetted by the oil and forms froth bubbles which float on the tank.
- The gangue gets settled at the bottom of the tank.
Gravity separation
- This method is based on separation of ore and gangue due to differences in the density of the particles.
- The ore is poured over a vibrating sloped table with grooves.
- A jet of water is allowed to flow over it.
- Denser ore particles settle down in the grooves, and lighter gangue particles are washed down by the water.

Extraction of Metal from Concentrated Ore

Different methods are used to obtain pure metal form the concentrated ore.
Generally, the metals are to be reduced with a suitable agent like coke, carbon monoxide, or hydrogen.
For this purpose, various types of furnaces are used.
For separating iron, a blast furnace is used.

Extraction of Iron

First, the ore is crushed and washed with water to remove sand and clay.
Then the ore is enriched by magnetic separators.
The concentrated ore is then put into a blast furnace.
Along with ore, limestone and coke powder are added to the furnace.
Hot air is blown into it.

Reactions in the Blast Furnace

C + O2 \rightarrow CO2\uparrow + heat
CO2 + C \rightarrow 2CO
CaCO3 \rightarrow CaO + CO2
CaO + SiO2 \rightarrow CaSiO3 (slag)
Fe2O3 + 3 CO \rightarrow 2Fe + 3CO2
Molten iron is collected at the bottom of the furnace.
The slag of calcium silicate floats on the molten iron and is removed.

Extraction of Aluminum

Purification of bauxite (Al2O3.2H2O)
Powdered bauxite is heated with NaOH under high pressure.
Al2O3 of the ore forms sodium aluminate which is water-soluble.
Silica reacts with sodium hydroxide to form soluble sodium silicate.
The iron oxide impurities from the ore are removed by filtration.
Aluminum hydroxide is added to it, due to which ore gets precipitated.
It is then heated and is converted to Al2O3.
This mineral is heated in an electric furnace. It melts at 1000 degrees Celsius.
Cryolite (Na3AlF6) is added as flux.
Al2O3 is reduced by graphite rods to pure aluminum.

Roasting

It is a process of heating concentrated ore in excess air.
Due to this, volatile gases escape out.

Calcination

It is a process of heating concentrated ore in the absence of air with calcium compounds at temperatures less than the melting point of the ore.

Properties and Uses of Some Metals and Alloys

Zinc
- Galvanizing (thin layer of zinc on iron sheets).
- Dry cells (zinc container as cathode).
- Zinc alloys are brass, bronze, german silver.
- Zn gives hardness to base metal copper.
Aluminum
- Household utensils as it is a good conductor of heat and unaffected by food acids.
- Powder is used in anti-corrosive paint.
- Foil used for packaging.
- Duralumin, magnalium are alloys with copper and magnesium, used to make aircraft parts.
- Al powder + Fe2O3 is used as thermite mixture for welding iron.
Pig iron
- Is impure iron.
- Drain pipes, gutter covers, railings.
- Easy to cast.
- Expands after solidification.
Steel
- Iron with many different elements to give desirable properties.
Copper
- Electric cables, calorimeters, utensils, alloys of copper – brass, bronze, german silver, bell metal and gun metal.
Lead
- High specific gravity.
- Used in bullets.
- Uses – flexible pipes, lead alloys like solder with low melting point, fuse wire, type metal (printing blocks).
Magnesium
- Fire works, photography powder (burns with dazzling light).
Amalgam
- An alloy in which the base metal is mercury.

Heat Treatment

A treatment is given to metal alloys to improve its desirable qualities like hardness, toughness is called heat treatment.
It involves heating and cooling the alloy to a required temperature in a controlled way.

Hardening or Quenching

It is a process in which steel is heated till it becomes red hot to temperatures above 800 degrees Celsius.
Then it is suddenly plunged into cold water or oil.
Due to this, hardness increases, but steel also becomes more brittle.

Annealing or Tempering

It is a process in which hardened steel is heated at temperatures between 220 degrees Celsius to 300 degrees Celsius.
Then it is cooled very slowly over a period of four to five hours.
This increases the toughness of the steel.
It retains the hardness but reduces the brittleness.

Some Metals and Ores from Which They Are Extracted

Aluminum
- Aluminum oxide (hydrous). Al2O3.2H2O (bauxite, alumina).
- It is a very stable compound and cannot be reduced by carbon. Hence, it is electrolyzed to get pure metal.
- Sodium aluminum fluoride (cryolite) Na3AlF6
Iron
- Hematite (Fe2O3)
- Magnetite (Fe3O4 – it is magnetic).
- Iron pyrites FeS2
- Siderite (ferrous carbonate FeCO3).
Copper
- Copper pyrites CuFeS2
- Copper glance Cu2S
- Cuprite Cu2O
- Malachite Cu(OH)2.CuCO3
- Azurite Cu(OH)2.2CuCO3

Allotropy

It is the existence of an element in more than one form in the same physical state having the same chemical properties but different physical properties.

Non-Metals

Sulphur

Sulfur is an odorless and tasteless yellowish solid. It is insoluble in water and slightly soluble in organic solvents.
It is readily soluble in carbon disulfide CS2.
It is a bad conductor of heat and electricity.
It is a non-metal with crystalline allotropes of shape rhombic and monoclinic.
It can also exist in a close structure of 8 atoms forming S8 molecule.
The Frasch process is used to get sulfur from underground.
Sulfur has a low melting point (115 degrees Celsius).
Heating of natural rubber with sulfur to definite temperatures for a required period of time is called vulcanization of rubber.
Sulfur atoms act as bridges between rubber molecules and initiate cross-linking, converting the soft rubber into hard rubber.
Sulfur is also useful in making sulfuric acid, matches, gunpowder, explosives, antiseptic creams.

Carbon

Though it is a non-metal, it is a good conductor of electricity.
It is used as electrodes.
Charcoal, lamp black, coke, graphite, and diamond are all forms of carbon.
Diamond is the hardest substance naturally found.
It has a very high refractive index of 2.41.
It is not a good conductor of electricity, but is a very good conductor of heat.
If it is burnt, carbon dioxide gas is formed.
It is naturally found near volcanoes or coal mines.
It is used as gemstones, tools to cut glass, mirrors, drilling rocks, and diamond knives are used in surgery.
To make artificial diamonds, 100,000 atm pressure and 3700 degrees Celsius temperature are used.
Artificial diamonds are used to make cutting tools.

Graphite

Graphite is an allotrope of carbon.
It is made up of layers of carbon that can slide over each other easily.
Graphite is a soft material and a good conductor of electricity.
It has a density of 1.9 to 2.3 g/cc, and a melting point of 3730 degrees Celsius.
It burns and produces carbon dioxide.
Graphite and clay are used in pencils.
It is black and slippery.
Each layer is made up of 6 carbon atoms.
Forces between two layers of graphite are weak.
It is used as a lubricant in machines, to make electrodes, in pencils, printer ink, and graphite fibers used to reinforce plastic, fishing rods, dish antennas, tennis rackets, and bicycle frames.

Fullerenes

Hardest substance – made in 1985 by heating graphite to a very high temperature.
It was named as ‘Buckminster fullerene’.
It had 60 carbon atoms in a hexagon-like structure making a football-like arrangement.
Now C70, C90, and C120 are also discovered.
They are used as superconductors, lubricants, catalysts, and to reinforce plastic.

Silicon

Each atom of silicon can join with 4 other silicon atoms, forming a silicon wafer.
It is a gray-colored metalloid and is abundant on the earth's crust, present in sand as silicon dioxide SiO2.
It is also present in flint, quartz, opal, and mica.
It is a semiconductor and is used to make microprocessor chips.
SiC (silicon carbide) is a very hard substance used to make cutting tools.
It has a high melting point of 1410 degrees Celsius.
Sodium silicate Na2SiO3 is called water glass. In this solution, different salts like copper sulfate, ferrous sulfate are dropped. After a few hours, they form tube-like structures which look like artificial plants. This is called silica garden.

Phosphorus – P4

Occurrence - Phosphorite Ca3(PO4)2; Chlorapatite 3Ca3(PO4)2.CaCl2; Fluorapatite 3Ca3(PO4)2.CaF2
Bones of animals contain phosphorus.
In pure form, it is white waxy, soft, and poisonous with a garlic-like odor.
It turns yellow because of the coating of red phosphorus and catches fire at 30 degrees Celsius. Hence, it is kept under water.
It shows phosphorescence and glows in the dark with slow combustion.
Red phosphorus is produced by heating yellow phosphorus in an inert atmosphere of CO2 or N2. Iodine is used as a catalyst. Red phosphorus is not as reactive as yellow, and it does not show phosphorescence.
Phosphorus can react with oxygen to form phosphorus pentachloride or trichloride.
White phosphorus can react with hot concentrated sodium hydroxide to form phosphine and sodium hypophosphite.
- P4 + 3NaOH + 3 H2O \rightarrow PH3 + 3NaH2PO2

Study of Some Compounds of Metals and Non-Metals

Baking soda (sodium bicarbonate) NaHCO3
- White amorphous powder, soluble in water.
- Used in baking as it makes bread lighter and spongy and in fire extinguishers.
- 2NaHCO3 (heating)\rightarrow Na2CO3 + H2O\uparrow + CO2\uparrow
Washing soda (sodium carbonate) Na2CO3.H2O
- White crystalline solid, soluble in water, efflorescent (loses water of crystallization and forms powder).
- It is used as a cleaning agent for domestic purposes, softening of hard water, making detergents, paper and water glass (sodium metasilicate Na2SiO3 used as refractories, and in cements, automobiles.).
- Na2CO3 + HCl \rightarrow NaCl + H2O + CO2\uparrow (similar reaction with H2SO4).
Calcium carbonate (limestone) CaCO3
- Present in chalk, marble. White amorphous powder, insoluble in water. If heated, it disintegrates to CaO and CO2.
- Uses: marble, paints, tooth powders, tooth pastes.
Ferrous sulfate (green vitriol) FeSO4.7H2O
- Light green crystalline solid, efflorescent. In air forms white anhydrous powder FeSO4.
- It acts as a reducing agent and can reduce KMnO4 and make it colorless. Used as an insecticide, as a reagent in the laboratory, preparing ink, making Mohr’s salt.
Copper sulfate (blue vitriol) CuSO4.5H2O
- Blue crystalline solid, soluble in water, efflorescent. Uses – Bordeaux mixture as insecticide and pesticide, electroplating of copper, in Daniell cell, used with Benedict's solution to find the presence of sugar in urine.
Potassium aluminum sulfate (alum) K2SO4.Al2(SO4)3.24H2O
- Crystalline colorless solid, water-soluble, has astringent taste, and is acidic. Used in medicine, in the paper industry, to stop bleeding, and in the purification of drinking water.
Plaster of Paris (calcium sulfate anhydride) (CaSO4)2.H2O
- It is prepared from gypsum.
- 2(CaSO4.2H2O) (heat) \rightarrow (CaSO4)2.H2O + 3H2O \uparrow.
- If water is added into plaster of Paris, after drying it gets hardened. Used for sealing laboratory equipment to make them airtight and to set fractured bones at the right positions.
Bleaching powder (calcium oxychloride) or chloride of lime CaOCl2
- It has a strong smell of chlorine, is soluble in water, and is used for bleaching clothes, in the paper and textile industries, and for disinfecting water.