Give reason why transition metal act as catalyst

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why transition metals act as catalysts variable oxidation states adsorption reactants

Transition metals act as good catalysts because:

They show variable oxidation states
They can easily gain or lose electrons during a reaction and then return to their original oxidation state. This provides an alternative reaction pathway with lower activation energy.
They form temporary intermediate compounds
Their partially filled d-orbitals allow them to bond temporarily with reactant molecules. This weakens existing bonds in the reactants, making reaction easier.
Their surfaces adsorb reactants
In solid transition-metal catalysts such as iron, nickel, platinum, or palladium, reactant molecules are adsorbed onto the metal surface. The molecules are brought close together and correctly oriented, so they react faster.

Example: iron catalyzes ammonia production in the Haber process, while nickel catalyzes hydrogenation of vegetable oils.

According to NCERT

Searching the Web

site:ncert.nic.in transition metals catalysts variable oxidation states NCERT chemistry

According to NCERT, transition metals and their compounds act as good catalysts because of their ability to:

adopt multiple oxidation states, and
form complexes with reactants.

In heterogeneous catalysis, reactant molecules form temporary bonds with atoms on the metal surface. This facilitates the reaction by providing an alternative pathway.

Examples: (V_2O_5) in the Contact process, finely divided Fe in the Haber process, and Ni in hydrogenation. NCERT Class XII, The d- and f-Block Elements

Give reason transition element show colour compound

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site:ncert.nic.in lech104 transition metal compounds coloured d d transition colour

According to NCERT, transition-metal compounds are generally coloured because their ions have partially filled d-orbitals.

When visible light falls on them, an electron absorbs a particular wavelength of light and jumps from one d-orbital to another of higher energy. This is called a d-d transition. The remaining transmitted or reflected light appears as the observed colour.

Ions with (d^0) or (d^{10}) configuration are generally colourless because no d-d transition is possible, for example (Sc^{3+}) and (Zn^{2+}). See NCERT Class XII Chemistry.

Explain why Zn Cd and Hg are not considered as transition element

Zn, Cd and Hg are d-block elements, but they are not considered transition elements because their atoms and their common ions have completely filled d-orbitals:

Zn: ([Ar],3d^{10}4s^2)
Cd: ([Kr],4d^{10}5s^2)
Hg: ([Xe],4f^{14}5d^{10}6s^2)

Their most stable ions, (Zn^{2+}), (Cd^{2+}), and (Hg^{2+}), also have (d^{10}) configuration.

According to NCERT, a transition element must have an incompletely filled d-orbital in its atom or in at least one stable oxidation state. Since Zn, Cd and Hg do not satisfy this condition, they are not transition elements. NCERT Class XII Chemistry

Explain why transition-metal ions are generally coloured

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site:ncert.nic.in/textbook/pdf/lech104.pdf transition metal ions coloured d orbitals absorption visible light

Transition-metal ions are generally coloured because they usually have partially filled d-orbitals.

In the presence of ligands such as water molecules, the d-orbitals split into different energy levels. An electron can absorb light of a particular wavelength and move from a lower-energy d-orbital to a higher-energy d-orbital. This is called a d-d transition.

The absorbed light is usually in the visible region. Therefore, the ion appears in the complementary colour of the light absorbed.

For example, (Cu^{2+}) ions appear blue because they absorb light of the complementary colour.

Ions having (d^0) or (d^{10}) configurations, such as (Sc^{3+}) and (Zn^{2+}), are colourless since d-d transition is not possible. This follows the explanation in NCERT Class XII Chemistry.

Explain lanthanoid contraction

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site:ncert.nic.in/textbook/pdf/lech104.pdf lanthanoid contraction poor shielding 4f atomic ionic radii

Lanthanoid contraction is the gradual decrease in the atomic and ionic radii of lanthanoids from La to Lu.

Cause

Across the lanthanoid series, atomic number increases and electrons are added to the 4f orbitals. The 4f electrons have poor shielding effect. Therefore, the increasing nuclear charge attracts the outer electrons more strongly, causing a gradual decrease in size.

Consequences

Lanthanoids have very similar properties, so their separation is difficult.
The elements of the second and third transition series have nearly the same sizes, for example:
- (Zr) and (Hf)
- (Nb) and (Ta)
The basic strength of lanthanoid hydroxides decreases from (La(OH)_3) to (Lu(OH)_3).

This matches the NCERT explanation that incomplete shielding by 4f electrons causes the contraction. NCERT Class XII Chemistry

Make a quick NCERT revision table for d- and f-block elements

NCERT Quick Revision: d- and f-Block Elements

Topic	Key NCERT Points
d-block elements	Elements in which the last electron enters the ((n-1)d) orbital. Groups 3-12. General configuration: ((n-1)d^{1-10}ns^{0-2}).
Transition elements	Elements having partially filled d-orbitals in atom or in one of their stable oxidation states.
Zn, Cd, Hg	d-block but not transition elements because both their atoms and common (M^{2+}) ions have (d^{10}) configuration.
Electronic configurations	Exceptions: Cr = (3d^5 4s^1), Cu = (3d^{10}4s^1). Similar exceptions occur in heavier members.
Atomic radii	Decrease slightly across a transition series, then remain almost constant due to poor shielding by d-electrons.
Ionisation enthalpy	Intermediate between s- and p-block elements. Irregular variation due to stable half-filled and fully filled d-subshells.
Oxidation states	Variable because energies of (ns) and ((n-1)d) orbitals are similar. Highest oxidation state increases up to Mn, then decreases.
Common oxidation states	Sc: +3; Ti: +2, +3, +4; V: +2 to +5; Cr: +2, +3, +6; Mn: +2 to +7; Fe: +2, +3; Co: +2, +3; Ni: +2; Cu: +1, +2; Zn: +2.
Stability of oxidation states	Higher oxidation states are more stable in oxides and fluorides. Lower oxidation states are more stable with heavier transition elements.
Colour of ions	Due to d-d transitions. Electrons absorb visible light and jump between split d-orbitals. Observed colour is complementary to absorbed light.
Colourless ions	Ions with (d^0) or (d^{10}) configuration are generally colourless, e.g., (Sc^{3+}), (Ti^{4+}), (Zn^{2+}), (Cu^+).
Magnetic behaviour	Caused by unpaired electrons. More unpaired electrons means greater paramagnetism. ( \mu = \sqrt{n(n+2)}) BM, where (n) = number of unpaired electrons.
Catalytic property	Due to variable oxidation states and complex formation. Solid metals also adsorb reactants on their surface.
Alloy formation	Similar atomic sizes allow transition metals to replace one another in crystal lattices, forming alloys.
Interstitial compounds	Small atoms like H, B, C, and N occupy gaps in metal lattice. They are hard, have high melting points, and retain metallic conductivity. Example: steel, (TiC).
Complex formation	Transition metals form complexes due to small size, high charge, and availability of vacant orbitals. Examples: ([Fe(CN)_6]^{3-}), ([Cu(NH_3)_4]^{2+}).
(K_2Cr_2O_7)	Orange crystalline solid; strong oxidising agent in acidic medium. Chromium oxidation state is +6.
(KMnO_4)	Deep purple solid; strong oxidising agent in acidic, neutral, and alkaline media. Manganese oxidation state is +7.

f-Block Elements

Topic	Lanthanoids	Actinoids
Series	14 elements following La	14 elements following Ac
Orbital filled	4f orbitals	5f orbitals
General configuration	([Xe]4f^{1-14}5d^{0-1}6s^2)	([Rn]5f^{1-14}6d^{0-1}7s^2)
Main oxidation state	+3	+3, but show wider range
Other oxidation states	+2 and +4 in some cases	+3 to +7 are common
Radioactivity	Mostly non-radioactive, except Pm	All actinoids are radioactive
Complex formation	Less extensive	More extensive
Nature of bonding	Compounds mainly ionic	Compounds show greater covalent character
Occurrence	Occur together in minerals	Many are synthetic or occur in very small amounts
Reactivity	Less reactive than actinoids	More reactive, especially finely divided metals

Important f-Block Concepts

Concept	NCERT Revision Point
Lanthanoid contraction	Gradual decrease in atomic and ionic radii from La to Lu.
Cause	Poor shielding by 4f electrons, so effective nuclear charge increases across the series.
Effects of lanthanoid contraction	Separation of lanthanoids is difficult; 4d and 5d transition elements have similar sizes, e.g., Zr and Hf.
Basicity of hydroxides	Decreases from (La(OH)_3) to (Lu(OH)_3) due to decreasing ionic size.
Colour of lanthanoid ions	Mainly due to f-f transitions. (La^{3+}) and (Lu^{3+}) are colourless because they are (f^0) and (f^{14}), respectively.
Magnetism of lanthanoids	Usually paramagnetic due to unpaired 4f electrons.
Mischmetal	Alloy containing about 95% lanthanoid metals, used in lighter flints and special steels.
Important use of (Ce^{4+})	Used as an oxidising agent in volumetric analysis.

One-Line Exam Answers

Question	Answer
Why do transition elements show variable oxidation states?	Because (ns) and ((n-1)d) orbitals have nearly the same energy.
Why are transition-metal ions coloured?	Due to d-d transition of electrons after absorption of visible light.
Why are Zn, Cd and Hg not transition elements?	Their atoms and common ions have completely filled (d^{10}) orbitals.
Why do transition metals form complexes?	Due to small size, high charge, and vacant orbitals.
Why are transition metals good catalysts?	Due to variable oxidation states, complex formation, and adsorption of reactants.
What causes lanthanoid contraction?	Ineffective shielding of increasing nuclear charge by 4f electrons.

Make a one-page PDF revision sheet

Reading File

Searching the Web

site:ncert.nic.in/textbook/pdf/lech104.pdf d and f block elements NCERT

Browsing Directory

Running Command

mkdir -p "/tmp/workspace/d-f-block-revision/output" 66 python - <<'PY' from reportlab.lib.pagesizes import A4 from reportlab.pdfgen import canvas from reportlab.lib import colors from reportlab.lib.units import cm from reportlab.pdfbase.pdfmetrics import stringWidth from reportlab.pdfbase.ttfonts import TTFont from reportlab.pdfbase import pdfmetrics from reportlab.pdfbase.pdfmetrics import registerFontFamily from reportlab.pdfbase.ttfonts import TTFont import os out='/tmp/workspace/d-f-block-revision/output/NCERT_d_f_Block_One_Page_Revision.pdf' W,H=A4 c=canvas.Canvas(out,pagesize=A4) c.setTitle('NCERT d- and f-Block Elements - One-Page Revision Sheet') # Fonts font='/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf' bold='/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf' pdfmetrics.registerFont(TTFont('DejaVu','%s'%font)) pdfmetrics.registerFont(TTFont('DejaVuBold','%s'%bold)) registerFontFamily('DejaVu',normal='DejaVu',bold='DejaVuBold') margin=28 blue=colors.HexColor('#123B5D'); teal=colors.HexColor('#006B6B'); pale=colors.HexColor('#EAF3F7'); yellow=colors.HexColor('#FFF5D6'); ink=colors.HexColor('#15222E'); gray=colors.HexColor('#5A6570') c.setFillColor(blue); c.rect(0,H-66,W,66,fill=1,stroke=0) c.setFillColor(colors.white); c.setFont('DejaVuBold',17); c.drawString(margin,H-31,'d- AND f-BLOCK ELEMENTS') c.setFont('DejaVu',8.5); c.drawString(margin,H-47,'NCERT Class XII Chemistry | One-page rapid revision') def wrap(text,fontname,fontsize,width): words=text.split(); lines=[]; cur='' for w in words: cand=(cur+' '+w).strip() if stringWidth(cand,fontname,fontsize)<=width: cur=cand else: lines.append(cur); cur=w if cur: lines.append(cur) return lines def box(x,y,w,h,title,items,accent=teal,fs=7.15): c.setFillColor(colors.white); c.setStrokeColor(colors.HexColor('#BFD0DA')); c.roundRect(x,y,w,h,5,fill=1,stroke=1) c.setFillColor(accent); c.roundRect(x,y+h-19,w,19,5,fill=1,stroke=0); c.rect(x,y+h-19,w,5,fill=1,stroke=0) c.setFillColor(colors.white); c.setFont('DejaVuBold',8.4); c.drawString(x+7,y+h-13,title) yy=y+h-28 for label,text in items: c.setFillColor(ink); c.setFont('DejaVuBold',fs); prefix=label+' ' if label else '' # label + content wrapping visually lines=wrap(prefix+text,'DejaVu',fs,w-14) for i,line in enumerate(lines): if yy<y+7: return c.setFont('DejaVuBold' if (i==0 and label) else 'DejaVu',fs) c.drawString(x+7,yy,u'• '+line if i==0 else ' '+line) yy-=fs+2.2 yy-=1.4 colgap=10; x1=margin; cw=(W-2*margin-colgap)/2; x2=x1+cw+colgap # 3 left, 3 right box(x1,534,cw,230,'1. d-BLOCK AND TRANSITION ELEMENTS',[ ('d-block:','last electron enters (n-1)d orbital; Groups 3-12.'), ('General EC:','(n-1)d1-10 ns0-2.'), ('Transition element:','partially filled d-orbital in atom or in a stable oxidation state.'), ('Zn, Cd, Hg:','d-block, not transition elements: atoms and common M2+ ions are d10.'), ('Exceptions:','Cr = 3d5 4s1; Cu = 3d10 4s1.'), ('Size:','radii decrease slightly across a series, then become nearly constant.'), ],blue) box(x2,534,cw,230,'2. KEY PROPERTIES OF TRANSITION METALS',[ ('Oxidation state:','variable because ns and (n-1)d orbitals have similar energies.'), ('Colour:','partially filled d-orbitals allow d-d transition on absorption of visible light. d0/d10 ions generally colourless.'), ('Magnetism:','unpaired electrons cause paramagnetism; µ = √n(n+2) BM.'), ('Catalysis:','variable oxidation states, complex formation, and adsorption on metal surface.'), ('Complexes:','small size, high charge, and vacant orbitals.'), ('Alloys:','similar radii permit mutual substitution in crystal lattice.'), ('Interstitial:','H, B, C or N in lattice gaps; hard, high mp, retain conductivity.'), ],blue) box(x1,299,cw,222,'3. IMPORTANT REAGENTS AND EXAMPLES',[ ('K2Cr2O7:','orange; Cr in +6 state; strong oxidising agent in acidic medium.'), ('KMnO4:','deep purple; Mn in +7 state; oxidising agent in acidic, neutral and alkaline media.'), ('Catalysts:','V2O5 in Contact process; finely divided Fe in Haber process; Ni in hydrogenation.'), ('Typical states:','Sc +3; Ti +2,+3,+4; V +2 to +5; Cr +2,+3,+6; Mn +2 to +7; Fe +2,+3; Cu +1,+2; Zn +2.'), ('High states:','more stable in oxides and fluorides.'), ],teal) box(x2,299,cw,222,'4. f-BLOCK: LANTHANOIDS VS ACTINOIDS',[ ('Lanthanoids:','14 elements following La; 4f filling; [Xe] 4f1-14 5d0-1 6s2; mainly +3.'), ('Actinoids:','14 following Ac; 5f filling; [Rn] 5f1-14 6d0-1 7s2; variable +3 to +7.'), ('Radioactivity:','all actinoids radioactive; most lanthanoids are not (Pm is radioactive).'), ('Comparison:','actinoids show greater covalency, complex formation, oxidation-state range and reactivity.'), ('Ln colour:','due to f-f transitions. La3+ (f0) and Lu3+ (f14) are colourless.'), ],teal) box(x1,112,cw,174,'5. LANTHANOID CONTRACTION',[ ('Definition:','gradual decrease in atomic and ionic radii from La to Lu.'), ('Cause:','4f electrons shield poorly; effective nuclear charge rises across the series.'), ('Consequences:','lanthanoids have very similar properties, so separation is difficult.'), ('Also:','similar sizes of 4d and 5d pairs, e.g. Zr and Hf.'), ('Basicity:','Ln(OH)3 decreases from La(OH)3 to Lu(OH)3.'), ],colors.HexColor('#7A4C12')) box(x2,112,cw,174,'6. ONE-LINE EXAM ANSWERS',[ ('Why colour?','d-d transition after absorption of visible light.'), ('Why variable O.S.?','near-equal ns and d orbital energies.'), ('Why complexes?','small, highly charged ions with vacant orbitals.'), ('Why catalysts?','multiple oxidation states and complex formation.'), ('Why Zn/Cd/Hg not transition?','no incomplete d-subshell in atoms/common ions.'), ('Mischmetal:','about 95% lanthanoid metals; used in lighter flints and special steels.'), ],colors.HexColor('#7A4C12')) # Footer c.setStrokeColor(colors.HexColor('#BFD0DA')); c.line(margin,93,W-margin,93) c.setFillColor(gray); c.setFont('DejaVu',6.6); c.drawString(margin,80,'Based on NCERT, Chemistry Part II, Chapter 4: The d- and f-Block Elements.') c.drawRightString(W-margin,80,'Revision sheet | 2025-26 NCERT edition') c.save() print(out) PY python - <<'PY' from pypdf import PdfReader p='/tmp/workspace/d-f-block-revision/output/NCERT_d_f_Block_One_Page_Revision.pdf' r=PdfReader(p) print('pages=',len(r.pages),'size=',__import__('os').path.getsize(p),'textchars=',len(r.pages[0].extract_text())) PY

Running Command

mkdir -p "/tmp/workspace/d-f-block-revision/output"; python -c "from reportlab.lib.pagesizes import A4; from reportlab.pdfgen import canvas; from reportlab.lib import colors; from reportlab.lib.units import cm; p='/tmp/workspace/d-f-block-revision/output/NCERT_d_f_Block_One_Page_Revision.pdf'; W,H=A4; c=canvas.Canvas(p,pagesize=A4); c.setTitle('NCERT d- and f-Block Elements - One-Page Revision Sheet'); blue=colors.HexColor('#123B5D'); teal=colors.HexColor('#006B6B'); ink=colors.HexColor('#15222E'); gray=colors.HexColor('#5A6570'); m=28; c.setFillColor(blue); c.rect(0,H-66,W,66,fill=1,stroke=0); c.setFillColor(colors.white); c.setFont('Helvetica-Bold',17); c.drawString(m,H-31,'d- AND f-BLOCK ELEMENTS'); c.setFont('Helvetica',8.5); c.drawString(m,H-47,'NCERT Class XII Chemistry | One-page rapid revision'); cw=(W-2*m-10)/2; x1=m; x2=m+cw+10; import textwrap; def box(x,y,w,h,title,items,accent):\n c.setFillColor(colors.white); c.setStrokeColor(colors.HexColor('#BFD0DA')); c.roundRect(x,y,w,h,5,fill=1,stroke=1); c.setFillColor(accent); c.roundRect(x,y+h-19,w,19,5,fill=1,stroke=0); c.rect(x,y+h-19,w,5,fill=1,stroke=0); c.setFillColor(colors.white); c.setFont('Helvetica-Bold',8.3); c.drawString(x+7,y+h-13,title); yy=y+h-29; c.setFillColor(ink); \n for lab,txt in items:\n lines=textwrap.wrap(lab+' '+txt,width=53);\n for i,line in enumerate(lines):\n c.setFont('Helvetica-Bold' if i==0 else 'Helvetica',6.7); c.drawString(x+7,yy,('• ' if i==0 else ' ')+line); yy-=8.5;\n yy-=1.6\n\n; box(x1,534,cw,230,'1. d-BLOCK AND TRANSITION ELEMENTS',[('d-block:','last electron enters (n-1)d orbital; Groups 3-12.'),('General EC:','(n-1)d1-10 ns0-2.'),('Transition element:','partially filled d-orbital in atom or a stable oxidation state.'),('Zn, Cd, Hg:','d-block, not transition: atoms and common M2+ ions are d10.'),('Exceptions:','Cr = 3d5 4s1; Cu = 3d10 4s1.'),('Size:','radii decrease slightly, then remain nearly constant.')],blue); box(x2,534,cw,230,'2. KEY PROPERTIES OF TRANSITION METALS',[('Oxidation state:','variable because ns and (n-1)d orbitals have similar energies.'),('Colour:','d-d transition after absorption of visible light. d0/d10 ions generally colourless.'),('Magnetism:','unpaired electrons cause paramagnetism; mu = root n(n+2) BM.'),('Catalysis:','variable oxidation states, complex formation and adsorption.'),('Complexes:','small size, high charge and vacant orbitals.'),('Alloys:','similar radii permit substitution in crystal lattice.'),('Interstitial:','H, B, C or N in gaps; hard and high melting.')],blue); box(x1,299,cw,222,'3. IMPORTANT REAGENTS AND EXAMPLES',[('K2Cr2O7:','orange; Cr +6; strong oxidising agent in acidic medium.'),('KMnO4:','deep purple; Mn +7; oxidising agent in acidic, neutral and alkaline media.'),('Catalysts:','V2O5 Contact process; Fe Haber process; Ni hydrogenation.'),('Typical states:','Sc +3; Ti +2,+3,+4; V +2 to +5; Cr +2,+3,+6; Mn +2 to +7; Fe +2,+3; Cu +1,+2; Zn +2.'),('High states:','more stable in oxides and fluorides.')],teal); box(x2,299,cw,222,'4. f-BLOCK: LANTHANOIDS VS ACTINOIDS',[('Lanthanoids:','14 after La; 4f filling; [Xe] 4f1-14 5d0-1 6s2; mainly +3.'),('Actinoids:','14 after Ac; 5f filling; [Rn] 5f1-14 6d0-1 7s2; +3 to +7.'),('Radioactivity:','all actinoids radioactive; most lanthanoids are not (Pm is radioactive).'),('Comparison:','actinoids show greater covalency, complex formation and reactivity.'),('Ln colour:','f-f transitions; La3+ (f0) and Lu3+ (f14) are colourless.')],teal); box(x1,112,cw,174,'5. LANTHANOID CONTRACTION',[('Definition:','gradual decrease in atomic and ionic radii from La to Lu.'),('Cause:','poor shielding by 4f electrons; effective nuclear charge rises.'),('Effects:','similar properties make separation difficult.'),('Also:','similar 4d and 5d sizes, e.g. Zr and Hf.'),('Basicity:','Ln(OH)3 decreases from La(OH)3 to Lu(OH)3.')],colors.HexColor('#7A4C12')); box(x2,112,cw,174,'6. ONE-LINE EXAM ANSWERS',[('Why colour?','d-d transition after visible-light absorption.'),('Why variable O.S.?','near-equal ns and d orbital energies.'),('Why complexes?','small, highly charged ions with vacant orbitals.'),('Why catalysts?','multiple oxidation states and complex formation.'),('Why Zn/Cd/Hg not transition?','no incomplete d-subshell in common ions.'),('Mischmetal:','about 95% lanthanoid metals; lighter flints and special steels.')],colors.HexColor('#7A4C12')); c.setStrokeColor(colors.HexColor('#BFD0DA')); c.line(m,93,W-m,93); c.setFillColor(gray); c.setFont('Helvetica',6.6); c.drawString(m,80,'Based on NCERT Chemistry Part II, Ch. 4: The d- and f-Block Elements.'); c.drawRightString(W-m,80,'One-page revision sheet'); c.save(); print(p)"; python -c "from pypdf import PdfReader; import os; p='/tmp/workspace/d-f-block-revision/output/NCERT_d_f_Block_One_Page_Revision.pdf'; r=PdfReader(p); print(len(r.pages),os.path.getsize(p),len(r.pages[0].extract_text()))"

Writing File

~/d-f-block-revision/make_sheet.py

from reportlab.lib.pagesizes import A4
from reportlab.pdfgen import canvas
from reportlab.lib import colors
from pypdf import PdfReader
import os, textwrap

out = '/tmp/workspace/d-f-block-revision/output/NCERT_d_f_Block_One_Page_Revision.pdf'
os.makedirs(os.path.dirname(out), exist_ok=True)
W, H = A4
c = canvas.Canvas(out, pagesize=A4)
c.setTitle('NCERT d- and f-Block Elements - One-Page Revision Sheet')
blue = colors.HexColor('#123B5D')
teal = colors.HexColor('#006B6B')
ink = colors.HexColor('#15222E')
gray = colors.HexColor('#5A6570')
m = 28

c.setFillColor(blue)
c.rect(0, H-66, W, 66, fill=1, stroke=0)
c.setFillColor(colors.white)
c.setFont('Helvetica-Bold', 17)
c.drawString(m, H-31, 'd- AND f-BLOCK ELEMENTS')
c.setFont('Helvetica', 8.5)
c.drawString(m, H-47, 'NCERT Class XII Chemistry | One-page rapid revision')

cw = (W - 2*m - 10) / 2
x1, x2 = m, m + cw + 10

def box(x, y, w, h, title, items, accent):
    c.setFillColor(colors.white)
    c.setStrokeColor(colors.HexColor('#BFD0DA'))
    c.roundRect(x, y, w, h, 5, fill=1, stroke=1)
    c.setFillColor(accent)
    c.roundRect(x, y+h-19, w, 19, 5, fill=1, stroke=0)
    c.rect(x, y+h-19, w, 5, fill=1, stroke=0)
    c.setFillColor(colors.white)
    c.setFont('Helvetica-Bold', 8.3)
    c.drawString(x+7, y+h-13, title)
    yy = y+h-29
    c.setFillColor(ink)
    for label, text in items:
        lines = textwrap.wrap(label+' '+text, width=53)
        for i, line in enumerate(lines):
            c.setFont('Helvetica-Bold' if i == 0 else 'Helvetica', 6.7)
            c.drawString(x+7, yy, ('• ' if i == 0 else '  ') + line)
            yy -= 8.5
        yy -= 1.6

box(x1, 534, cw, 230, '1. d-BLOCK AND TRANSITION ELEMENTS', [
    ('d-block:', 'last electron enters (n-1)d orbital; Groups 3-12.'),
    ('General EC:', '(n-1)d1-10 ns0-2.'),
    ('Transition element:', 'partially filled d-orbital in atom or a stable oxidation state.'),
    ('Zn, Cd, Hg:', 'd-block, not transition: atoms and common M2+ ions are d10.'),
    ('Exceptions:', 'Cr = 3d5 4s1; Cu = 3d10 4s1.'),
    ('Size:', 'radii decrease slightly, then remain nearly constant.')], blue)

box(x2, 534, cw, 230, '2. KEY PROPERTIES OF TRANSITION METALS', [
    ('Oxidation state:', 'variable because ns and (n-1)d orbitals have similar energies.'),
    ('Colour:', 'd-d transition after absorption of visible light. d0/d10 ions generally colourless.'),
    ('Magnetism:', 'unpaired electrons cause paramagnetism; mu = root n(n+2) BM.'),
    ('Catalysis:', 'variable oxidation states, complex formation and adsorption.'),
    ('Complexes:', 'small size, high charge and vacant orbitals.'),
    ('Alloys:', 'similar radii permit substitution in crystal lattice.'),
    ('Interstitial:', 'H, B, C or N in gaps; hard and high melting.')], blue)

box(x1, 299, cw, 222, '3. IMPORTANT REAGENTS AND EXAMPLES', [
    ('K2Cr2O7:', 'orange; Cr +6; strong oxidising agent in acidic medium.'),
    ('KMnO4:', 'deep purple; Mn +7; oxidising agent in acidic, neutral and alkaline media.'),
    ('Catalysts:', 'V2O5 Contact process; Fe Haber process; Ni hydrogenation.'),
    ('Typical states:', 'Sc +3; Ti +2,+3,+4; V +2 to +5; Cr +2,+3,+6; Mn +2 to +7; Fe +2,+3; Cu +1,+2; Zn +2.'),
    ('High states:', 'more stable in oxides and fluorides.')], teal)

box(x2, 299, cw, 222, '4. f-BLOCK: LANTHANOIDS VS ACTINOIDS', [
    ('Lanthanoids:', '14 after La; 4f filling; [Xe] 4f1-14 5d0-1 6s2; mainly +3.'),
    ('Actinoids:', '14 after Ac; 5f filling; [Rn] 5f1-14 6d0-1 7s2; +3 to +7.'),
    ('Radioactivity:', 'all actinoids radioactive; most lanthanoids are not (Pm is radioactive).'),
    ('Comparison:', 'actinoids show greater covalency, complex formation and reactivity.'),
    ('Ln colour:', 'f-f transitions; La3+ (f0) and Lu3+ (f14) are colourless.')], teal)

brown = colors.HexColor('#7A4C12')
box(x1, 112, cw, 174, '5. LANTHANOID CONTRACTION', [
    ('Definition:', 'gradual decrease in atomic and ionic radii from La to Lu.'),
    ('Cause:', 'poor shielding by 4f electrons; effective nuclear charge rises.'),
    ('Effects:', 'similar properties make separation difficult.'),
    ('Also:', 'similar 4d and 5d sizes, e.g. Zr and Hf.'),
    ('Basicity:', 'Ln(OH)3 decreases from La(OH)3 to Lu(OH)3.')], brown)

box(x2, 112, cw, 174, '6. ONE-LINE EXAM ANSWERS', [
    ('Why colour?', 'd-d transition after visible-light absorption.'),
    ('Why variable O.S.?', 'near-equal ns and d orbital energies.'),
    ('Why complexes?', 'small, highly charged ions with vacant orbitals.'),
    ('Why catalysts?', 'multiple oxidation states and complex formation.'),
    ('Why Zn/Cd/Hg not transition?', 'no incomplete d-subshell in common ions.'),
    ('Mischmetal:', 'about 95% lanthanoid metals; lighter flints and special steels.')], brown)

c.setStrokeColor(colors.HexColor('#BFD0DA'))
c.line(m, 93, W-m, 93)
c.setFillColor(gray)
c.setFont('Helvetica', 6.6)
c.drawString(m, 80, 'Based on NCERT Chemistry Part II, Ch. 4: The d- and f-Block Elements.')
c.drawRightString(W-m, 80, 'One-page revision sheet')
c.save()

reader = PdfReader(out)
assert len(reader.pages) == 1
assert len(reader.pages[0].extract_text()) > 500
print(out, os.path.getsize(out), 'bytes')

Running Command

python "/tmp/workspace/d-f-block-revision/make_sheet.py"

NCERT d f Block One Page Revision

PDF Document · PDF

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