Group Properties & Trends

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ஆசிரியர்களுக்கு: Group Properties & Trends (Chemistry, CIE)-க்கான தயாரான பாட ஸ்லைடுகள், திருப்புதல் குறிப்புகள் — உங்கள் பாடத்தில் அவற்றைப் பயன்படுத்தவும், அல்லது மாணவர்கள் நேரலை விளையாட்டாக விளையாடும் ஊடாடும் வகுப்பு செயல்பாடாக தலைப்பை இயக்கவும்.

பாட குறிப்புகள்

Group I (Alkali Metals) – Physical Properties

Group I metals are called alkali metals because they form alkaline solutions with water.
They are soft and can be cut with a knife; softness increases down the group.
Freshly cut surfaces are shiny and silvery.
They have low melting points (some melt on a hot day) and low densities compared to other metals.
Melting point decreases down the group; density generally increases (with an early exception).
They are good conductors of heat and electricity.

Group I metals on the Periodic Table

Group I – Chemical Properties & Reactivity

All have one electron in their outer shell, which they readily lose to form +1 ions.
They react vigorously with water: 2M(s) + 2H₂O(l) → 2MOH(aq) + H₂(g).
Reactivity increases down the group (Li < Na < K < Rb < Cs < Fr).
Lithium: fizzes, moves on surface; Sodium: more vigorous, melts into a ball; Potassium: burns with a lilac flame.
They react with oxygen and water vapour in air, so are stored under oil.
Rubidium and caesium react explosively with water; francium is extremely reactive but rare/radioactive.

Bohr model of sodium (Group I) showing one outer electron.

Group VII (Halogens) – Physical Properties

Halogens are diatomic non-metals (F₂, Cl₂, Br₂, I₂, At₂).
All have seven electrons in their outer shell and gain one electron to form halide ions.
At room temperature: chlorine is a pale yellow-green gas, bromine is a red-brown liquid, iodine is a grey-black solid.
Melting and boiling points increase down the group; density also increases.
Colour darkens down the group: fluorine (yellow), chlorine (pale green), bromine (red-brown), iodine (grey-black), astatine (black).
Aqueous solutions: chlorine (very pale green, often colourless), bromine (orange/yellow), iodine (brown).

Physical states of the halogens at room temperature

Group VII – Reactivity & Displacement Reactions

Reactivity decreases down the group (opposite to Group I).
A more reactive halogen displaces a less reactive halogen from its halide solution.
Chlorine displaces bromine from KBr: 2KBr(aq) + Cl₂(aq) → 2KCl(aq) + Br₂(aq) (orange colour).
Chlorine displaces iodine from KI: brown colour of iodine appears.
Bromine displaces iodine from KI: brown colour of iodine appears.
No reaction occurs if the halogen is less reactive than the halide (e.g., iodine + KCl).

Summary table of displacement reactions

Transition Elements

Transition elements are metals found in the centre of the Periodic Table (between Group 2 and 3).
They are hard, strong, lustrous, and conduct heat and electricity; most have high melting points (except mercury).
They form ions with different charges (e.g., Fe²⁺ and Fe³⁺) and have variable oxidation states.
They form coloured compounds (e.g., copper sulfate is blue, copper oxide is black).
They are useful as catalysts (e.g., iron in the Haber process).
Scandium and zinc are not considered transition elements as they have only one oxidation state and form colourless compounds.

Coloured compounds formed by transition metal ions

Noble Gases

Noble gases are in Group VIII; they are monatomic, colourless gases at room temperature.
They have very low melting and boiling points and are unreactive (inert).
Inertness is due to their full outer electron shells (e.g., He: 2, Ne: 2,8, Ar: 2,8,8).
Full outer shells mean they have no tendency to gain, lose, or share electrons.
They are used in lighting (neon signs) and as inert atmospheres (argon in welding).

Noble gases on the Periodic Table

Trends Summary

Group I: reactivity increases down; melting point decreases; density increases (with early exception).
Group VII: reactivity decreases down; melting/boiling point increases; colour darkens; density increases.
Noble gases: all are unreactive; boiling points increase down the group (He lowest, Rn highest).
Transition elements: high melting points, variable oxidation states, coloured compounds, catalytic activity.

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1.How many electrons are in the outer shell of a Group I metal atom?
Easy
- A1
- B2
- C7
- D8
2.Which of the following is a physical property of Group I metals?
Easy
- AThey are hard and strong
- BThey have high melting points
- CThey are soft and easy to cut
- DThey are gases at room temperature
3.What is the trend in reactivity of Group I metals as you go down the group?
Easy
- AReactivity decreases
- BReactivity increases
- CReactivity stays the same
- DReactivity first increases then decreases
4.Which halogen is a red-brown liquid at room temperature?
Easy
- AChlorine
- BBromine
- CIodine
- DFluorine
5.What is the trend in reactivity of Group VII elements as you go down the group?
Easy
- AReactivity increases
- BReactivity decreases
- CReactivity stays the same
- DReactivity first decreases then increases
6.Which of the following is a characteristic property of transition elements?
Easy
- AThey form colourless compounds
- BThey have only one oxidation state
- CThey form coloured compounds
- DThey are gases at room temperature
7.Why are noble gases unreactive?
Easy
- AThey have a full outer shell of electrons
- BThey have one electron in their outer shell
- CThey are diatomic molecules
- DThey have low melting points
8.Which of the following is a physical property of noble gases?
Easy
- AThey are coloured
- BThey are monatomic
- CThey are liquids at room temperature
- DThey are reactive

மேலும் கேள்விகள்

9.What is the colour of iodine in aqueous solution?
Easy
- APurple
- BBrown
- COrange
- DColourless
10.Which of the following statements about Group I metals is correct?
Easy
- AThey are stored under oil to prevent reaction with air
- BThey have high densities compared to other metals
- CThey have high melting points
- DThey are non-metals
11.Which of the following is a difference between transition elements and Group I metals?
Medium
- ATransition elements are softer
- BTransition elements have lower melting points
- CTransition elements form ions with different charges
- DTransition elements are more reactive with water
12.A student adds chlorine water to a colourless solution of potassium bromide. Which colour change is observed?
Medium
- AColourless to orange
- BColourless to brown
- CColourless to green
- DColourless to purple
13.The table shows the melting points of some Group I metals. Which melting point is most likely for rubidium? | Element | Melting point (°C) | |---|---| | Lithium | 180 | | Sodium | 98 | | Potassium | 63 | | Rubidium | ? |
Medium
- A39 °C
- B85 °C
- C120 °C
- D200 °C
14.Astatine is a halogen below iodine in Group VII. Which of the following is the most likely colour and physical state of astatine at room temperature?
Medium
- ABlack solid
- BPale yellow gas
- CRed-brown liquid
- DGrey-black solid
15.The electronic configuration of a noble gas is 2,8,8. Which element is this?
Easy
- AArgon
- BNeon
- CKrypton
- DXenon
16.A student reacts sodium with water and collects the hydrogen gas produced. If 0.46 g of sodium produces 240 cm³ of hydrogen at room temperature and pressure, what volume of hydrogen would be produced from 0.23 g of sodium?
Medium
- A120 cm³
- B240 cm³
- C480 cm³
- D60 cm³
17.Which of the following is a property of transition elements but not of Group I metals?
Medium
- AThey form coloured compounds
- BThey are soft and easy to cut
- CThey have low melting points
- DThey react vigorously with water
18.A student adds bromine water to a solution of potassium iodide. What colour change is observed?
Medium
- AColourless to brown
- BColourless to orange
- COrange to colourless
- DBrown to colourless
19.The melting points of the halogens increase down Group VII. Which of these halogens has the highest melting point?
Easy
- AIodine
- BBromine
- CChlorine
- DFluorine
20.A student investigates the reaction of lithium with water. Which observation is correct?
Medium
- AThe lithium fizzes and moves on the surface
- BThe lithium burns with a lilac flame
- CThe lithium dissolves rapidly
- DThe lithium reacts explosively
21.The density of sodium is 0.97 g/cm³ and the density of potassium is 0.86 g/cm³. What is the trend in density down Group I?
Medium
- ADensity increases
- BDensity decreases
- CDensity stays the same
- DDensity fluctuates
22.A student adds a few drops of chlorine water to a colourless solution of potassium iodide. Which colour change is observed?
Medium
- AColourless to orange
- BColourless to brown
- CColourless to green
- DColourless to purple
23.A student adds bromine water to a solution of potassium chloride. Which colour change is observed?
Medium
- ANo change
- BOrange to colourless
- CColourless to orange
- DColourless to brown
24.A student investigates the reaction of sodium with water. The student measures the temperature change and finds it increases from 20°C to 30°C. Which statement about the reaction is correct?
Easy
- AThe reaction is endothermic because the temperature increases.
- BThe reaction is exothermic because the temperature increases.
- CThe reaction is endothermic because the temperature decreases.
- DThe reaction is exothermic because the temperature decreases.
25.A student adds a piece of lithium to cold water. Which observation would NOT be made?
Medium
- AFizzing
- BThe lithium moves on the surface of the water
- CA lilac flame
- DThe lithium dissolves slowly
26.A student is given a sample of an unknown element. It is a grey-black solid at room temperature. It forms a diatomic molecule and has seven electrons in its outer shell. Which element is it most likely to be?
Medium
- AChlorine
- BBromine
- CIodine
- DAstatine
27.A student adds chlorine water to a solution of potassium bromide. The mixture turns orange. Which equation represents the reaction?
Medium
- ACl2 + 2KBr → 2KCl + Br2
- BCl2 + KBr → KCl + Br2
- CBr2 + 2KCl → 2KBr + Cl2
- DCl2 + 2KBr → 2KCl + 2Br
28.Which element is a transition element?
Easy
- ASodium
- BIron
- CChlorine
- DNeon
29.What is the colour of iodine vapour?
Easy
- ABrown
- BPurple
- CGrey-black
- DYellow-green
30.What is the general name for the Group I metals?
Easy
- Aalkali metals
- Balkaline earth metals
- Chalogens
- Dnoble gases
31.Why are Group I metals stored under oil?
Easy
- ATo keep them shiny.
- BTo stop them reacting with oxygen and water vapour in air.
- CTo prevent them from melting.
- DTo make them easier to cut.
32.When potassium reacts with water, what colour flame is produced?
Easy
- Ayellow
- Blilac
- Cgreen
- Dorange
33.What is the trend in melting point of Group I metals as you go down the group?
Easy
- AIt increases.
- BIt decreases.
- CIt stays the same.
- DIt increases then decreases.
34.Which of the following is a property of transition elements that is NOT typical of Group I metals?
Medium
- AThey conduct electricity.
- BThey are lustrous.
- CThey form coloured compounds.
- DThey have low densities.
35.How many electrons are in the outer shell of a halogen atom?
Easy
- A1
- B2
- C7
- D8
36.What is the colour of bromine at room temperature?
Easy
- Apale yellow-green gas
- Bred-brown liquid
- Cgrey-black solid
- Dcolourless gas
37.Group I metals are called alkali metals because they react with water to form alkaline solutions.
Easy
True or false?
38.Arrange the following Group I metals in order of increasing reactivity (least reactive first).
Medium
- potassium
- lithium
- sodium
39.Halogens are monoatomic.
Easy
True or false?
40.Which statement explains why the reactivity of halogens decreases down the group?
Medium
- AThe atomic radius decreases, making it easier to gain an electron.
- BThe number of electron shells increases, reducing the attraction for an incoming electron.
- CThe outer shell has more electrons, making it harder to gain an electron.
- DThe melting point increases, making the halogen less reactive.
41.Match each halogen to its colour in aqueous solution.
Medium
- Chlorine
- Bromine
- Iodine
- Orange
- Brown
- Very pale green (usually colourless)
42.Transition elements form ions with different charges and are useful as catalysts.
Medium
True or false?
43.Which of the following is NOT a typical property of transition elements?
Medium
- AThey form coloured compounds.
- BThey have variable oxidation states.
- CThey are gases at room temperature.
- DThey are good conductors of heat and electricity.
44.Which of the following are properties of noble gases? (Select all that apply)
Medium
- AColourless
- BMonoatomic
- CHighly reactive
- DGaseous at room temperature
- EHave full outer electron shells
45.Match each halogen to its colour at room temperature.
Medium
- Chlorine
- Bromine
- Iodine
- red-brown liquid
- pale yellow-green gas
- grey-black solid
46.Complete the sentence.
Easy
Group I metals are stored under oil to prevent them from reacting with ____ and ____ in the air.

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