Chemistry Periodic Table
Key Concepts & Formulas
Provide 5-7 essential concepts for Chemistry Periodic Table:
| # | Concept | Quick Explanation |
|---|---|---|
| 1 | Atomic Number | Number of protons in nucleus; determines element’s identity and position in periodic table |
| 2 | Periodic Law | Properties of elements repeat periodically when arranged by increasing atomic number |
| 3 | Groups/Periods | Vertical columns (18 groups) share valence electrons; horizontal rows (7 periods) share energy levels |
| 4 | Metallic Character | Decreases left→right across period; increases top→bottom in group |
| 5 | Atomic Radius | Distance nucleus→outermost electron; decreases left→right; increases top→bottom |
| 6 | Valence Electrons | Electrons in outermost shell; determines chemical reactivity (Group number for main groups) |
| 7 | Electronegativity | Atom’s ability to attract electrons; increases left→right; decreases top→bottom (F=4.0 max) |
10 Practice MCQs
Generate 10 MCQs with increasing difficulty (Q1-3: Easy, Q4-7: Medium, Q8-10: Hard)
Q1. Which element is in Group 1 and Period 3 of the periodic table? A) Hydrogen B) Sodium C) Magnesium D) Potassium
Answer: B) Sodium
Solution: Group 1 = alkali metals (1 valence electron) Period 3 = 3 electron shells Na (11): 2,8,1 configuration → Group 1, Period 3
Shortcut: Group 1 metals: Li (P2), Na (P3), K (P4) - remember “LiNaK”
Concept: Chemistry Periodic Table - Position identification
Q2. The most electronegative element in periodic table is: A) Oxygen B) Fluorine C) Chlorine D) Nitrogen
Answer: B) Fluorine
Solution: Electronegativity values: F=4.0, O=3.5, Cl=3.0, N=3.0 Fluorine (top right corner) has highest electronegativity
Shortcut: “FONCl” order - Fluorine > Oxygen > Nitrogen ≈ Chlorine
Concept: Chemistry Periodic Table - Electronegativity trend
Q3. Which element has the smallest atomic radius in Period 2? A) Lithium B) Carbon C) Nitrogen D) Fluorine
Answer: D) Fluorine
Solution: Atomic radius decreases left→right due to increasing nuclear charge Period 2: Li > Be > B > C > N > O > F Fluorine (rightmost) has smallest radius
Shortcut: “Size shrinks right” - smallest is rightmost in period
Concept: Chemistry Periodic Table - Atomic radius trend
Q4. A station’s water purification system uses elements from Group 17. Which sequence shows correct decreasing order of oxidizing ability? A) F₂ > Cl₂ > Br₂ > I₂ B) I₂ > Br₂ > Cl₂ > F₂ C) Cl₂ > F₂ > Br₂ > I₂ D) Br₂ > Cl₂ > F₂ > I₂
Answer: A) F₂ > Cl₂ > Br₂ > I₂
Solution: Group 17: oxidizing ability decreases down the group F (top) strongest oxidizer, I (bottom) weakest Order: F₂ > Cl₂ > Br₂ > I₂
Shortcut: “Oxidation power drops as you descend” - F strongest at top
Concept: Chemistry Periodic Table - Group 17 properties
Q5. Railway tracks contain manganese steel. If element X is in the same group as Mn (Group 7) but Period 5, what is its atomic number? A) 43 B) 45 C) 47 D) 49
Answer: A) 43
Solution: Mn = Period 4, Group 7, Atomic number 25 Period 5, Group 7 = Technetium (Tc) Atomic number = 25 (Mn) + 18 (next period transition) = 43
Shortcut: Transition metals: add 18 to get same group, next period
Concept: Chemistry Periodic Table - Transition metal pattern
Q6. Diesel locomotive emission catalyst contains platinum group metals. Which pair has similar chemical properties? A) Fe & Co B) Pd & Pt C) Cu & Zn D) Na & Mg
Answer: B) Pd & Pt
Solution: Similar chemical properties occur within same group Pd (Group 10, Period 5) and Pt (Group 10, Period 6) Both are platinum group metals with similar catalytic properties
Shortcut: Same group = similar properties (vertical neighbors)
Concept: Chemistry Periodic Table - Group characteristics
Q7. Buffer solution in railway lab has pH 10. Which oxide of Period 3 element forms basic solution? A) Na₂O B) Al₂O₃ C) SO₃ D) Cl₂O₇
Answer: A) Na₂O
Solution: Period 3 oxide basicity: Na₂O (basic) > MgO (basic) > Al₂O₃ (amphoteric) > SiO₂ (acidic) > P₄O₁₀ (acidic) > SO₃ (acidic) > Cl₂O₇ (acidic) Only Na₂O forms basic solution: Na₂O + H₂O → 2NaOH
Shortcut: “Left oxides basic, right oxides acidic” in period
Concept: Chemistry Periodic Table - Oxide properties across period
Q8. Railway signal lamps use rare earth elements. If lanthanide element has atomic number 65, how many f-electrons does it have? A) 8 B) 9 C) 10 D) 11
Answer: B) 9
Solution: Element 65 = Terbium (Tb) Lanthanide formula: f-electrons = Atomic number - 54 (Xe) - 2 (6s electrons) Tb: 65 - 54 - 2 = 9 f-electrons Configuration: [Xe] 4f⁹ 6s²
Shortcut: Lanthanides: f-electrons = Z - 56 (after Ba)
Concept: Chemistry Periodic Table - Lanthanide configuration
Q9. High-speed rail overhead lines use copper alloy. If element Y forms Y²⁺ ion with electron configuration [Ar]3d¹⁰, what is its position and which element is it? A) Group 11, Period 4, Copper B) Group 12, Period 4, Zinc C) Group 10, Period 4, Nickel D) Group 9, Period 4, Cobalt
Answer: B) Group 12, Period 4, Zinc
Solution: Y²⁺ = [Ar]3d¹⁰ → Neutral atom = [Ar]3d¹⁰4s² This is Zn (Z=30): 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² Group 12, Period 4
Shortcut: d¹⁰s² configuration = Group 12 (Zn, Cd, Hg)
Concept: Chemistry Periodic Table - Transition metal ions
Q10. Railway tanker carries element with atomic number 35. How many elements in periodic table have lower first ionization energy than this element but higher atomic number? A) 5 B) 7 C) 9 D) 11
Answer: C) 9
Solution: Element 35 = Bromine (Br) Ionization energy decreases down groups, increases across periods Elements with lower IE than Br but Z > 35:
- In same period (Z=36-54): Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru (9 elements)
- Rb (Z=37) starts lower IE trend
Shortcut: Next alkali metal (Rb) and following elements have lower IE
Concept: Chemistry Periodic Table - Ionization energy trends
5 Previous Year Questions
Generate PYQ-style questions with authentic exam references:
PYQ 1. Which of the following elements has the highest metallic character? [RRB NTPC 2021 CBT-1]
Answer: Cesium
Solution: Metallic character increases down groups and decreases across periods. Cesium (Group 1, Period 6) is bottom-left element, showing maximum metallic character.
Exam Tip: Remember “bottom-left = most metallic” for quick identification questions
PYQ 2. The atomic number of elements X, Y, and Z are 12, 13, and 16 respectively. Which forms amphoteric oxide? [RRB Group D 2022]
Answer: Y (Aluminum)
Solution:
X (12) = Mg → basic oxide
Y (13) = Al → amphoteric oxide
Z (16) = S → acidic oxide
Al₂O₃ reacts with both acid and base
Exam Tip: Al, Zn, Pb, Sn form amphoteric oxides - remember “AZPS”
PYQ 3. Which group of periodic table is known as chalcogens? [RRB ALP 2018]
Answer: Group 16
Solution: Group 16 elements (O, S, Se, Te, Po) are called chalcogens, meaning “ore-forming” elements as they form many ores.
Exam Tip: Group names: 16=Chalcogens, 15=Pnictogens, 14=Crystallogens
PYQ 4. Electronic configuration of transition element in +3 oxidation state is [Ar]3d⁵. What is its atomic number? [RRB JE 2019]
Answer: 26 (Iron)
Solution: +3 state = [Ar]3d⁵ → Neutral atom = [Ar]3d⁶4s² This is Fe (Z=26): 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s²
Exam Tip: d⁵ configuration often indicates Fe³⁺ or Mn²⁺
PYQ 5. Which pair represents elements of same period but different groups? [RPF SI 2019]
Answer: Sodium and Magnesium
Solution: Na (Group 1, Period 3) and Mg (Group 2, Period 3) are in same period but different groups. Other options had same group or different periods.
Exam Tip: Check both period and group numbers for such pairing questions
Speed Tricks & Shortcuts
For Chemistry Periodic Table, provide exam-tested shortcuts:
| Situation | Shortcut | Example |
|---|---|---|
| Finding group from configuration | Valence electrons = Group no. (main groups) | Al: [Ne]3s²3p¹ → 3 valence e⁻ → Group 13 |
| Period determination | Highest principal quantum number = Period number | Br: [Ar]4s²3d¹⁰4p⁵ → n=4 → Period 4 |
| Metallic character trend | “MLB” - Metallic increases Moving Left & Bottom | Cs > Rb > K > Na > Li (down group 1) |
| Atomic size comparison | “Size shrinks right, grows down” | F < Cl < Br < I (down group) |
| Ionization energy order | “IE increases up and right” | He > F > O > N > C > B > Be > Li |
Common Mistakes to Avoid
| Mistake | Why Students Make It | Correct Approach |
|---|---|---|
| Confusing periods and groups | Mixing horizontal/vertical directions | Remember: Periods = horizontal like railway tracks, Groups = vertical like train coaches |
| Forgetting transition metal exceptions | Applying main group rules to d-block | Transition metals: (n-1)d fills before ns, but ns removes first in ions |
| Incorrectly predicting ionic charges | Assuming group number = charge always | Remember: Sn/Pb can show +2/+4, Transition metals variable charges |
| Misplacing lanthanides/actinides | Treating them as main groups | Lanthanides (4f) and actinides (5f) are separate series at bottom |
| Overlooking diagonal relationships | Only considering vertical/horizontal trends | Remember diagonal similarities: Li-Mg, Be-Al, B-Si have similar properties |
Quick Revision Flashcards
| Front (Question/Term) | Back (Answer) |
|---|---|
| Group 1 name? | Alkali metals |
| Group 17 name? | Halogens |
| Most electronegative element? | Fluorine (4.0) |
| Largest atom in Period 3? | Sodium |
| Elements in Group 18? | Noble gases |
| d-block elements range? | Atomic numbers 21-30, 39-48, 72-80 |
| Lanthanides start at? | Atomic number 58 (Cerium) |
| Diagonal relationship pair? | Li-Mg, Be-Al, B-Si |
| Amphoteric oxides examples? | Al₂O₃, ZnO, PbO, SnO |
| Transition series periods? | Period 4 (3d), 5 (4d), 6 (5d) |
Topic Connections
How Chemistry Periodic Table connects to other RRB exam topics:
- Direct Link: Chemical bonding - periodic trends determine ionic/covalent character
- Combined Questions: Reactivity series + periodic trends for displacement reactions
- Foundation For: Metallurgy - extraction methods depend on metal position in periodic table
- Physics Link: Electronic configuration basis for semiconductor physics (Group 14 elements)
- Environmental: Pollution control - understanding halogen/chalcogen chemistry for emission control
BETA
