LECTURE № 14 METALS 18.04.2016

bond
Properties of metals: physical, chemical
Extraction of metals
Applications and role of

metals. Alloys

metals.

Explain how the reactivity of metals changes across the periodic

table.

List out the uses of metals and alloys.

a material (an element, compound, or alloy) that is typically

hard, opaque, shiny, and has good electrical and thermal conductivity.
In chemical reaction: "Metals are the elements which form positive ions by losing electrons.“ They are also known as electropositive elements.
Metals are generally malleable — that is, they can be hammered or pressed permanently out of shape without breaking or cracking — as well as fusible (able to be fused or melted) and ductile (able to be drawn out into a thin wire).
About 91 of the 118 elements in the periodic table are metals (some elements appear in both metallic and non-metallic forms).

Cs, Fr
Alkali earth metals (group IIA): Be, Mg, Ca,

Sr, Ba, Ra
Transition metals (Group 3 – 12, d-elements): Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Cd, Os, Hg, Pt, Au, W
Iron Triad (Group 8, 9,10): Fe, Co & Ni = They create the magnetic field
Coinage Metals (Group 11): Cu, Ag, Au = They are used to make coins.

copper

silver

gold

Bi, Po
5) Lanthanides
6) Actinides
7) Elements which are possibly metals: meitnerium,

darmstadtium, roentgenium, ununtrium, ununpentium, livermorium, ununseptium
8) Elements which are sometimes considered metals: Ge, As, At, Sb

such as strength, malleability, ductility, luster, conduction of heat and

electricity.

Metallic bonding is the force of attraction between valence electrons and the metal positive ions.

Metallic Bonding

outer electrons to gain full shells, and become positive ions.

These negative “sea of electrons” move around between the metal ions. The negative electrons attract the positive ions, making the structure strong.
Metals are good at conducting electricity and heat because of the free electrons which are able to move around.

filament inside an electric bulb?

1) Tungsten can be drawn into

very thin metal wires.

2) Tungsten has the highest melting point (3422°C).

3) Tungsten has strong resistance to high temperature.

beaten into thin sheets.
Ductile - can be stretched into wire.
Metals

have a high melting point. They are also very dense.
Possess metallic luster.
Opaque as thin sheet.
Solid at room temperature (except Hg).

Heavy metals
Magnesium
1,74 g/cm3
Lead
11,3 g/cm3
Gold
19,3 g/cm3
Osmium
22,5 g/cm3
Lithium
0,53 g/cm3
Light metals have

density less than 5 g/cm3

Heavy metals have density greater than 5 g/cm3

be drawn into wire.
Malleable metals can be hammered into

sheets

and oxygen. This results in corrosion and rust:
Me +

O2 = MexOy
Me + [O] + H2O = Me(OH)n

The ability of metals to produce a particular sound when it is tapped on a hard surface is termed sonority.

in daily life.

shell.
Lose their valence electrons easily.
Form oxides that are basic.
Are good reducing agents
Have

lower (EN<1,5) electronegativities.

order of their reactivity is called reactivity series of metals:

K - Potassium
Na - Sodium Most
Ca - Calcium reactive
Mg - Magnesium
Al - Aluminium
Zn - Zinc Reactivity
Fe - Iron decreases
Pb - Lead
H - Hydrogen
Cu - Copper
Hg - Mercury Least
Ag - Silver reactive
Au - Gold

The activity series of metals is an empirical tool used to predict products in displacement reactions and reactivity of metals with water and acids in replacement reactions and ore extraction.

take place and how intense the reaction will be:
acid
gold
metal
reacts with
calcium
sodium
oxygen
oxygen
oxygen
silver
prediction
zinc
water
no

reaction

fizzing

burns vigorously

very slow reaction

burns moderately

oxides:
2Cu + O2 = 2CuO – Q
4Al + 3O2 =

2Al2O3 – Q
4Na + O2 = 2Na2O + Q

The most reactive metals as K, Na, Li, Ca and Mg react with oxygen and burn in air.
Metals from Al to Cu in the activity series of metals, react slowly when heated in air to form the metal oxides. Aluminium is the fastest and copper is the slowest of them.
Iron metal does not burn in dry air even on strong heating. In moist air, iron is oxidized to give rust:


Gold and platinum do not react with oxygen in air.

electrochemical series react with cold water or steam to produce

hydrogen:
Active metals at room temperature are formed hydroxides:


Medium active metals at high temperature with steam are formed oxides:


Sn, Pb, Cu, Ag, Au and Pt do not react with water or steam.

dilute HCl, forming the metal salt (either sulfate or chloride)

and hydrogen gas:






Zinc with dilute sulphuric acid is often used for the laboratory preparation of hydrogen. The reaction is slow at room temperature, but its rate can be increased by the addition of a little copper (II) sulphate. Zinc displaces copper metal, which acts as a catalyst.
Metals below hydrogen (Cu, Ag, Au, Pt), will not react with dilute acids. They cannot displace hydrogen from the non-metal anion.

REACTION WITH ACIDS

evolved when metals react with nitric acid (HNO3) because it

is a strong oxidising agent and it oxidizes the H2 produced to water and is itself reduced to nitrogen dioxide:
1) With active metals:
Mg + HNO3(dilut) = Mg(NO3)2 + H2O + NH3 (NH4NO3)
Mg + HNO3(conc) = Mg(NO3)2 + 4H2O + 2N2O
2) With passive metals:
Cu + HNO3(dilut) = Cu(NO3)2 + H2O + NO
3Cu + 8HNO3(conc) = 3Cu(NO3)2 + 4H2O + 2NO2

Reaction with concentrated sulfuric acid:
Me + H2SO4 (conc) = MeSO4 + H2O + (H2S, S, SO2)

Fe and Al will not react with conc H2SO4 acid, they are passivated.

they are passivates
Cr, Fe, Al, Pt, Ta, Ir
Concentrated acid

affect at the heavy metals, they are produced salt, water and NO2 gas

Heavy metals as
Cu, Ag, Au, Bi

Diluted acid affect at the heavy metals, they are produced salt, water and NO gas

Alkali and alkali earth metals and Sn, Fe

Concentrated acid affect at these metals, they are produced salt, water and N2O gas

Diluted acid affect at these metals, they are produced salt, water and NH3 gas (or salt NH4NO3)

if a metal will react with a metal compound. If

the metal is more reactive than the metal in the compound, it pushes out, or displaces, the less reactive metal from its compound.

If the metal is less reactive than the metal in the compound, it will not compete and so there is no reaction.

more reactive metal

less
reactive metal compound

more
reactive metal compound

less reactive metal

+



+

less reactive metal

more reactive metal compound

no reaction

+



reaction is one where a more reactive metal will displace

a cation of less reactive metal from a compound (salt, oxide:

-2,37 V
active
metal

+0,34 V
passive
metal

CuSO4

ZnSO4 + Cu
Iron displaces copper from copper (II) sulfate:
Fe + CuSO4 FeSO4 + Cu

after 15 – 20 minutes

reactive iron.
The reaction gets so hot that the iron

melts! It is used to weld railway tracks.

Aluminium + Iron oxide => Aluminium oxide + Iron

In this reaction, aluminium reacts with iron oxide to make aluminium oxide and iron:

gold, silver, platinum etc are found in the free state

(nugget) in the earth’s crust because they are least reactive. Most metals are found as oxides, carbonates, sulfides, halides etc.
Minerals: are elements or compounds which occur naturally inside the earth’s crust.
Ore: is a mineral from which metals can be extracted profitably.
Gangue: is the impurities present in the ore like rock particles, sand particles, clay particles etc.

metals

Passive, noble or precious metals
High active metals
are found in

the salt types (chloride, sulfate, carbonate, silicate, phosphate):

are found in the oxides and sulfides types:

are found in the free state (nuggets)

in the extraction of metals from their ores and refining

them are known as metallurgy.
Metals are extracted from their ores in three main steps. They are :
Concentration of the ore (Enrichment of the ore).
Reducing the metal compound to the metal (by O2, H2, C, CO, Al and electrolysis)
Refining (Purification of the metal by electrolysis).

in cryolite

Extracted by electrolysis of molten chlorides


Extraction by reduction of

oxides using carbon

Roasting ore by heating alone

Metals of Metals of Metals of
high reactivity medium reactivity low reactivity

Electrolysis of
molten ore Carbonate ore Sulfide ore Sulfide ore


Pure metal Calcination Roasting Roasting


Oxide of metal Metal

Reduction to metal Refining

Refining

Ore

are composed of two or more elements, with at least

one being metallic element.
Metals can be divided into two basic categories:
Ferrous
Non ferrous
Alloys are stronger and harder than pure metals and they also can with stand corrosion better. Pure metals are relatively a little softer (but they are still hard) and they have a low resistance to corrosion as they are affected by air and water easily. Hence alloys are used more often instead of pure metals. Nowadays, complex alloys have been made with specific desired properties. Usually, transition metals are used in the production of alloys.

includes steel and cast iron. Pure iron has limited commercial

use, but when alloyed with carbon. Iron has more uses and greater commercial value than any other metal.

Non ferrous (colored):
They include the other metallic elements and their alloys. They include metals and alloys of aluminum, copper, gold, silver and other metals.

with other metals or non metal:
Steel and cast iron –

iron, carbon
Stainless steel – iron, carbon, cobalt, nickel
Brass – copper, zinc
Bronze – copper, tin
Solder – Lead, tin (used for welding electrical wires together)
If one of the metals in an alloy is mercury, it is called an amalgam.