Frank Brothers Solutions for ICSE Class 10 Chemistry Chapter 7a Metals And Non Metals

Chapter 7. Metals and Non-metals

Solution 1:
Answer: Metals are the elements (except hydrogen) which form positive ions by losing electrons or donating electrons.
For example sodium metal forms positively charged sodium ion by losing one electron as follows:
\( Na \rightarrow Na^+ + e^- \)
Metals usually have 1, 2 or 3 electrons in the outermost shell.
Metals can conduct heat and electricity and they are also malleable and ductile.
• Five metals are sodium, potassium, magnesium, aluminium, calcium.
In simple words: Metals are elements that easily give away electrons to become positive ions, like how sodium becomes sodium ion by losing one electron.

📝 Teacher's Note: Use the analogy of metals being "generous donors" who give away electrons easily. Demonstrate with simple electron dot diagrams on the board to show electron loss.

🎯 Exam Tip: Always mention "form positive ions by losing electrons" and give the sodium example with the equation for full marks.

Solution 2:
Answer: Non-metals are the elements which form negative ions by accepting (or gaining electrons).
For example Chlorine forms negatively charged chloride ion by accepting one electron as follows:
\( Cl + e^- \rightarrow Cl^- \)
Non-metals usually have 4, 5, 6 or 7 electrons in their outermost shell.
Non-metals do not conduct heat and electricity and are neither malleable nor ductile. These are brittle in nature.
• Five non-metals are oxygen, nitrogen, silicon, phosphorous, chlorine.
In simple words: Non-metals are elements that like to gain electrons to become negative ions, opposite to what metals do.

📝 Teacher's Note: Contrast with metals by calling non-metals "electron acceptors" or "greedy for electrons." Use the chlorine example to show the opposite behavior from metals.

🎯 Exam Tip: Mention "form negative ions by gaining electrons" and contrast properties with metals - this comparison often fetches extra marks.

Solution 3:
Answer: Metal which exist in liquid state is mercury.
Non-metal which exist in liquid state is bromine.
Concept Insight: Metals are usually solid while non-metals exist in all the three states.
In simple words: At room temperature, almost all metals are solid except mercury which flows like water, and bromine is the only liquid non-metal.

📝 Teacher's Note: Show students a video or image of liquid mercury (safely) and bromine to make this memorable. Emphasize the exception nature of these elements.

🎯 Exam Tip: Remember the pair "Mercury-metal, Bromine-non-metal" for liquid state questions - this is frequently asked.

Solution 4:
Answer: The most abundant metal in the earth's crust is aluminium and the most abundant non-metal in the earth's crust is oxygen.
In simple words: If you could weigh all metals in Earth's outer layer, aluminium would be the heaviest, and oxygen would be the heaviest non-metal.

📝 Teacher's Note: Connect this to real life - aluminium foil, cans, and window frames are everywhere because it's so abundant. Oxygen makes up most of water and many rocks.

🎯 Exam Tip: Learn the pair "Aluminium-most abundant metal, Oxygen-most abundant non-metal" - this fact appears in many question variations.

Solution 5:
Answer: 1. Metals.
2. Non-metals.
3. Platinum and Gold.
4. Potassium and Sodium.
5. Potassium, Sodium and Calcium.
6. Iron.
7. Potassium and Sodium.
8. Platinum.
9. Platinum and Gold.
10. Mercuric oxide (HgO) and Silver oxide (\( Ag_2O \)).
11. Potassium hydroxide (KOH) and Sodium hydroxide (NaOH).
12. Potassium carbonate (\( K_2CO_3 \)) and Sodium carbonate (\( Na_2CO_3 \)).
13. Potassium carbonate (\( K_2CO_3 \)) and Sodium carbonate (\( Na_2CO_3 \)).
14. Potassium nitrate (\( KNO_3 \)) and Sodium nitrate (\( NaNO_3 \)).
15. Mercuric nitrate (\( Hg(NO_3)_2 \)) and silver nitrate (\( AgNO_3 \))
In simple words: This is a list of different categories of elements and compounds, mostly focusing on very reactive metals like potassium and sodium, and noble metals like gold and platinum.

📝 Teacher's Note: Group similar answers together when teaching - notice how potassium and sodium appear frequently because they're very reactive alkali metals.

🎯 Exam Tip: For "fill in the blanks" questions, if potassium is an answer, sodium is often the other answer, and vice versa.

Solution 6:
Answer: The arrangement of metals in a vertical column in the order of decreasing reactivity is called reactivity series of metals or activity series of metals.

In simple words: The reactivity series arranges metals from most reactive (like sodium) to least reactive, showing how differently they behave with air, water, and acids.

📝 Teacher's Note: Use the table to show students how sodium is much more violent in its reactions compared to iron - this helps them understand relative reactivity positions.

🎯 Exam Tip: When comparing two metals' reactivity, always mention their reactions with water and acids as key evidence - examiners look for these specific comparisons.

Solution 7:
Answer: 1. Fe < Zn < Mg < Na.
2. Na > Al > Cu > Fe
3. Ca > Mg > Fe > Cu.
In simple words: These show the order of metals from least reactive to most reactive, where sodium (Na) is always among the most reactive.

📝 Teacher's Note: Help students remember that in reactivity series, sodium and potassium are always at the top (most reactive), while gold and platinum are at the bottom (least reactive).

🎯 Exam Tip: Learn the common reactivity order: K > Na > Ca > Mg > Al > Zn > Fe > Cu > Ag > Au - this helps in all arrangement questions.

Solution 8:
Answer: (i) When sodium and potassium are placed in cold water they react vigorously to form their respective alkalis and hydrogen gas is evolved.
\( 2K + 2H_2O \rightarrow 2KOH + H_2 \)
\( 2Na + 2H_2O \rightarrow 2NaOH + H_2 \)
(ii) Burning magnesium continues to burn in steam to form oxide and hydrogen.
\( Mg + H_2O \rightarrow MgO + H_2 \)
(iii) Copper hydroxide when heated forms copper oxide and water.
\( Cu(OH)_2 \rightarrow CuO + H_2O \)
(iv) Potassium nitrate when heated strongly decompose to give potassium nitrite and oxygen gas.
\( 2KNO_3 (s) \rightarrow 2KNO_2 (s) + O_2 (g) \)
(v) Copper nitrate when heated strongly decompose to give copper oxide, nitrogen dioxide gas and oxygen gas.
\( 2Cu(NO_3)_2 (s) \rightarrow 2CuO (s) + 4NO_2 (g) + O_2 (g) \)
(vi) Mercuric nitrate when heated strongly decompose to yield mercury metal and nitrogen dioxide gas and oxygen gas.
\( Hg(NO_3)_2 (s) \rightarrow Hg (l) + 2NO_2 (g) + O_2 (g) \)
In simple words: These are different chemical reactions showing how metals behave with water, how compounds break down when heated, and what products are formed.

📝 Teacher's Note: Group these reactions by type - reactions with water (i,ii), decomposition by heat (iii,iv,v,vi) - this helps students see patterns in chemical behavior.

🎯 Exam Tip: Always balance chemical equations and include state symbols (s), (l), (g) where given - these details often carry separate marks in exams.