Elements are mostly metals (iron, copper, gold) or non-metals (oxygen, sulphur, carbon). Their properties decide their uses — copper for wires and pan bottoms, zinc to protect iron, aluminium for aircraft. Carbon is special: it forms millions of compounds, from diamond to every fuel and food. Exams love the exceptions and the everyday uses.
On this page you will learn:
- Metals vs non-metals, and the exceptions
- The reactivity series and ores
- Rusting and how galvanising stops it
- Alloys, and metals in living things
- Carbon: diamond, graphite and other forms
- Hydrocarbons, alcohols, soaps and detergents
4
Valency of carbon
It shares 4 electrons
Zn
Coat on galvanised iron
Asked in 4 PPSC/PSSSB papers
24
Carats in pure gold
Jewellery is often 22 carat
Metals and non-metals
Rule in one line: metals are shiny, malleable, ductile and good conductors; non-metals usually are not.
| Fact | Answer |
|---|---|
| Liquid metal at room temperature | Mercury |
| Liquid non-metal | Bromine |
| Metals soft enough to cut with a knife | Lithium, sodium, potassium |
| Lightest metal | Lithium |
| Metals that melt in the palm | Gallium, caesium |
| Shiny non-metal | Iodine |
| Non-metal that conducts electricity | Graphite |
| Hardest natural substance | Diamond |
| Best conductor of electricity | Silver, then copper |
| Most malleable and ductile | Gold |
| Highest melting point (bulb filament) | Tungsten |
QUICK CHECK
PYQ · PPSC OHE 2016 — Which of the following does NOT describe a metal?
Tap an option to answer
Answer: D — Brittle
Brittleness belongs to non-metals such as sulphur and phosphorus. Metals bend and stretch instead of breaking.
QUICK CHECK
PYQ · RSMSSB LDC 2024 — Which of the following metals can easily be cut with a knife?
Tap an option to answer
Answer: A — Lithium
Lithium, like sodium and potassium, is a soft alkali metal. Magnesium, aluminium and copper are much harder.
QUICK CHECK
PYQ · RSMSSB LDC 2024 — Sodium metal is stored in:
Tap an option to answer
Answer: A — Kerosene
Sodium catches fire with water and reacts with air, so it is kept under kerosene, which does not react with it.
Reactivity and ores
Rule in one line: a more reactive metal pushes a less reactive one out of its compound.
KEY TERM
Reactivity series
Metals listed from most to least reactive. Potassium and sodium at the top react violently with water. Gold and silver at the bottom hardly react, so they are found free in nature and used for jewellery.
K→Na→Ca→Mg→Al→Zn→Fe→Pb→Cu→Hg→Ag→Au
| Metal | Main ore |
|---|---|
| Aluminium | Bauxite |
| Iron | Haematite |
| Mercury | Cinnabar |
| Lead | Galena |
| Zinc | Zinc blende |
| Copper | Copper pyrites |
QUICK CHECK
PYQ · PPSC ICS 2016 — The metal extracted from the ore bauxite is
Tap an option to answer
Answer: A — Aluminium
Bauxite is purified to alumina, and aluminium is then taken out by electrolysis. Iron comes from haematite.
Rusting and how to stop it
Rule in one line: iron rusts only when both air (oxygen) and water are present.
HOW IRON RUSTS
- 1IronFe
- 2+ oxygen of air
- 3+ water or moisture
- 4RustHydrated iron oxide
| Method | How it works |
|---|---|
| Paint, oil, grease | Keeps air and water away |
| Galvanisation | A coat of zinc; zinc is more reactive and corrodes first, saving the iron |
| Tin plating | A coat of tin, used on food cans |
| Chromium plating | Shiny coat on taps and bicycle parts |
| Alloying | Stainless steel (with chromium and nickel) does not rust |
QUICK CHECK
PYQ · PPSC EO 2018 — Galvanised iron sheets are protected from rusting due to the presence of a layer of:
Tap an option to answer
Answer: C — Zinc
Galvanising is coating iron with zinc. PPSC SSO 2018 and PPSC SEVE 2016 asked the same fact.
QUICK CHECK
PYQ · PSSSB Election Kanungo 2018 — The process of coating iron pipes with a layer of zinc to prevent corrosion is termed as:
Tap an option to answer
Answer: B — Galvanization
Zinc coating is galvanization. Vulcanization is hardening rubber with sulphur; annealing is slow heating and cooling of metal.
QUICK CHECK
PYQ · RSMSSB LDC 2024 — Identify the statements which are incorrect with respect to rusting: (a) coat of paint on iron rods prevents rusting (b) galvanised water pipes are not normally used in homes (c) rusting is a physical change (d) salt water makes the process of rust formation faster.
Tap an option to answer
Answer: D — b and c only
(b) is wrong: galvanised pipes are common in homes. (c) is wrong: rusting is a chemical change. (a) and (d) are true.
Alloys and metals at work
Rule in one line: a metal is chosen for the job its properties suit best.
| Alloy | Made of | Use |
|---|---|---|
| Brass | Copper + zinc | Utensils, fittings |
| Bronze | Copper + tin | Statues, medals |
| Steel | Iron + a little carbon | Buildings, tools |
| Stainless steel | Iron + chromium + nickel + carbon | Utensils; does not rust |
| Solder | Lead + tin | Joining wires (low melting point) |
| Amalgam | Mercury + another metal | Dental fillings (older use) |
Copper
Pan bottoms, wires
Conducts heat far better than steel, so food heats evenly.
Magnesium
Chlorophyll
The metal at the centre of the green pigment of leaves.
Iron
Haemoglobin
The metal in the red pigment of blood that carries oxygen.
Mercury
Poison
Builds up in fish and people; it causes Minamata disease.
Metals at work in kitchens and in living things
QUICK CHECK
PYQ · PPSC EO 2018 — Why are stainless steel cooking pans fabricated with copper bottom?
Tap an option to answer
Answer: B — Conductivity of copper is more than the stainless steel
Copper is a much better conductor of heat. The copper base spreads heat quickly and evenly across the pan.
QUICK CHECK
PYQ · PPSC OHE 2016 — Chlorophyll is a naturally occurring compound in which the central metal is:
Tap an option to answer
Answer: D — Magnesium
Magnesium sits at the centre of chlorophyll. The similar ring in haemoglobin holds iron.
Carbon and its forms
Rule in one line: allotropes are different forms of the same element.
| Allotrope | Structure | Properties and uses |
|---|---|---|
| Diamond | Each carbon joined to 4 others in a rigid 3-D net | Hardest natural substance; does not conduct; cutting tools, jewellery |
| Graphite | Flat layers of hexagons that slide | Soft, slippery, conducts; pencil 'lead', lubricant, electrodes |
| Graphene | A single layer of graphite | Very strong and thin; conducts well |
| Fullerene | C60 molecules shaped like a football | Named after the architect Buckminster Fuller |
QUICK CHECK
PYQ · Punjab Police Constable 2021 — Diamond is made of which element?
Tap an option to answer
Answer: B — Carbon
Diamond is pure carbon. PPSC OHE 2016 asked the same: diamond is chemically pure carbon.
QUICK CHECK
PYQ · PPSC JEE 2022 — Carbon, diamond and graphite are together called:
Tap an option to answer
Answer: A — Allotropes
Diamond and graphite are allotropes: the same element, carbon, in different forms. Isotopes differ in neutrons, not in structure.
QUICK CHECK
PYQ · PPSC OHE 2016 — Which one of the following is not an allotrope of carbon?
Tap an option to answer
Answer: A — Coal
Coal is an impure mixture, not a pure form of carbon. Diamond, graphite and graphene are allotropes.
Carbon compounds, alcohols and soaps
Rule in one line: carbon shares electrons and links to itself in long chains, so it forms millions of compounds.
KEY TERM
Why carbon is special
Carbon has 4 outer electrons, which it shares to make covalent bonds (valency 4). Carbon atoms also join one another in long chains, branches and rings — this is catenation. Most carbon compounds are poor conductors and have low melting and boiling points.
4 outer electrons→Shares them→Joins other carbons→Millions of compounds
| Family | Carbon–carbon bond | First member |
|---|---|---|
| Alkanes (saturated) | Single only | Methane, CH4 |
| Alkenes (unsaturated) | At least one double | Ethene, C2H4 |
| Alkynes (unsaturated) | At least one triple | Ethyne (acetylene), C2H2 — welding |
| Name ends in | Family | Example |
|---|---|---|
| -ane | Alkane | Propane (in LPG) |
| -ol | Alcohol (–OH group) | Propanol, ethanol |
| -al | Aldehyde | Methanal (formalin) |
| -oic acid | Carboxylic acid | Ethanoic acid (vinegar) |
QUICK CHECK
PYQ · RSMSSB LDC 2024 — Identify from the following statements which are true for carbon compounds: (a) They form long chains of carbon atoms which are arranged in branch and ring structures. (b) They are good conductors of electricity. (c) They have high melting and boiling points. (d) They form covalent bonds.
Tap an option to answer
Answer: B — a and d only
Chains (a) and covalent bonds (d) are true. Carbon compounds are poor conductors and have low melting and boiling points.
QUICK CHECK
PYQ · PPSC OHE 2016 — A hydrocarbon in which all the atoms are connected by single bonds is:
Tap an option to answer
Answer: A — An alkane
Only single bonds means a saturated hydrocarbon: an alkane, such as methane. Alkenes have a double bond, alkynes a triple bond.
QUICK CHECK
PYQ · RSMSSB LDC 2024 — Propanol is an:
Tap an option to answer
Answer: D — Alcohol
The ending '-ol' means an –OH group, so propanol is an alcohol.
QUICK CHECK
PYQ · RSMSSB LDC 2024 — Identify the true statements related to soaps and detergents: (a) Soaps are sodium or potassium salts of long chain of sulphuric acids while detergents are generally sodium salts of carboxylic acids. (b) The soap molecules form micelles when they interact with water and dirt (Oil). (c) These micelles are able to pull out the dirt in water. (d) Soaps are effective in hardwater also. (e) The detergent remain ineffective in hard water.
Tap an option to answer
Answer: C — b and c
(b) and (c) are true. (a) swaps soap and detergent; soaps fail in hard water (d is false); detergents work in it (e is false).
Traps and practice
Last revision — where the options try to fool you.
COMMON TRAPS
- Brittle describes non-metals, not metals.
- Galvanising = zinc, not tin, lead or chromium.
- Vulcanisation is for rubber (with sulphur), not for iron.
- Rusting is a chemical change; salt water speeds it up.
- Chlorophyll has magnesium; haemoglobin has iron.
- Coal is not an allotrope of carbon; graphene is.
- Allotropes ≠ isotopes. '-ol' = alcohol; '-ane' = alkane.
CHECK YOURSELF
Why are electric wires made of copper and covered with plastic?
Show answer
Copper is a very good, ductile and cheap conductor; plastic is an insulator that keeps the current from reaching anyone who touches the wire.
FLASHCARDS
Metals and carbon flashcards
- Ore of aluminium
- Bauxite
- Sodium is kept in
- Kerosene
- Zinc coat on iron
- Galvanisation
- Metal in chlorophyll
- Magnesium
- Copper-bottom pans
- Copper conducts heat better
- Brass
- Copper + zinc
- Diamond and graphite
- Allotropes of carbon
- Only single C–C bonds
- Alkane
QUICK BYTES
- Liquid metal: mercury; liquid non-metal: bromine
- Li, Na, K: soft, cut with a knife, kept in kerosene
- Reactivity: K > Na > Ca > Mg > Al > Zn > Fe > Pb > Cu > Ag > Au
- Bauxite: aluminium; haematite: iron; galena: lead
- Rust needs air + water; zinc coat = galvanising
- Diamond hardest; graphite conducts; coal is not an allotrope
- Soap fails in hard water; detergent works