Chem-3: Classification of Elements and Periodicity in Properties30 Questions
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1. The modern periodic table arranges elements in order of increasing:
A. Atomic number
B. Atomic mass only
C. Number of neutrons
D. Density
Answer: A. Atomic number
Explanation: The modern periodic law states that properties of elements are periodic functions of their atomic number, forming the basis of the current table's arrangement.
2. Who proposed the modern periodic law based on atomic number?
A. Henry Moseley
B. Dmitri Mendeleev
C. John Newlands
D. Johann Döbereiner
Answer: A. Henry Moseley
Explanation: Henry Moseley's work established that atomic number, rather than atomic mass, is the fundamental basis for the periodic arrangement of elements.
3. Dmitri Mendeleev originally arranged elements in his periodic table based on increasing:
A. Atomic mass
B. Atomic number
C. Number of electrons
D. Ionisation energy
Answer: A. Atomic mass
Explanation: Mendeleev's original periodic table was organised primarily by increasing atomic mass, before the later refinement using atomic number.
4. The horizontal rows in the periodic table are called:
A. Periods
B. Groups
C. Blocks
D. Series
Answer: A. Periods
Explanation: Periods are the horizontal rows of the periodic table, indicating the number of electron shells present in the elements.
5. The vertical columns in the periodic table are called:
A. Groups
B. Periods
C. Blocks only
D. Series only
Answer: A. Groups
Explanation: Groups are the vertical columns, containing elements with similar chemical properties due to identical valence electron configurations.
6. The total number of periods in the modern periodic table is:
A. Seven
B. Eight
C. Six
D. Nine
Answer: A. Seven
Explanation: The modern periodic table consists of seven horizontal periods, representing increasing principal energy levels.
7. The total number of groups in the modern periodic table is:
A. Eighteen
B. Sixteen
C. Eight
D. Twenty
Answer: A. Eighteen
Explanation: The modern periodic table has eighteen vertical groups, numbered according to IUPAC convention.
8. Elements in the same group of the periodic table generally have similar chemical properties because they have the same:
A. Number of valence electrons
B. Atomic mass
C. Number of neutrons
D. Physical state
Answer: A. Number of valence electrons
Explanation: Elements within the same group share an identical number of electrons in their outermost shell, leading to similar chemical behaviour.
9. The energy required to remove the outermost electron from a neutral gaseous atom is called its:
A. Ionisation energy
B. Electron affinity
C. Electronegativity
D. Atomic radius
Answer: A. Ionisation energy
Explanation: Ionisation energy specifically measures the energy needed to remove the most loosely bound electron from an isolated gaseous atom.
10. The energy released when an electron is added to a neutral gaseous atom is called its:
A. Electron affinity
B. Ionisation energy
C. Electronegativity
D. Atomic radius
Answer: A. Electron affinity
Explanation: Electron affinity is the energy change associated with adding an electron to a neutral gaseous atom, forming a negative ion.
11. The tendency of an atom to attract shared electrons towards itself in a chemical bond is called its:
A. Electronegativity
B. Electron affinity
C. Ionisation energy
D. Atomic radius
Answer: A. Electronegativity
Explanation: Electronegativity measures how strongly an atom attracts the shared pair of electrons within a covalent bond.
12. As one moves across a period from left to right, atomic radius generally:
A. Decreases
B. Increases
C. Remains constant
D. Fluctuates randomly
Answer: A. Decreases
Explanation: Across a period, increasing nuclear charge pulls electrons closer to the nucleus, causing atomic radius to generally decrease.
13. As one moves down a group, atomic radius generally:
A. Increases
B. Decreases
C. Remains constant
D. Becomes zero
Answer: A. Increases
Explanation: Down a group, additional electron shells are added, increasing the distance between the nucleus and outermost electrons, thus increasing atomic radius.
14. As one moves across a period from left to right, ionisation energy generally:
A. Increases
B. Decreases
C. Remains constant
D. Becomes negative
Answer: A. Increases
Explanation: Across a period, increased nuclear charge holds electrons more tightly, generally increasing the ionisation energy required to remove them.
15. As one moves down a group, ionisation energy generally:
A. Decreases
B. Increases
C. Remains constant
D. Becomes zero
Answer: A. Decreases
Explanation: Down a group, the increased distance and shielding effect make outer electrons easier to remove, generally decreasing ionisation energy.
16. As one moves across a period from left to right, electronegativity generally:
A. Increases
B. Decreases
C. Remains constant
D. Becomes negative
Answer: A. Increases
Explanation: Electronegativity generally increases across a period as atoms have a stronger pull on shared electrons due to increasing nuclear charge.
17. Elements in Group 1 of the periodic table are called:
A. Alkali metals
B. Alkaline earth metals
C. Halogens
D. Noble gases
Answer: A. Alkali metals
Explanation: Group 1 elements, excluding hydrogen, are known as alkali metals, characterised by high reactivity and a single valence electron.
18. Elements in Group 2 of the periodic table are called:
A. Alkaline earth metals
B. Alkali metals
C. Halogens
D. Noble gases
Answer: A. Alkaline earth metals
Explanation: Group 2 elements are termed alkaline earth metals, having two valence electrons and generally being less reactive than alkali metals.
19. Elements in Group 17 of the periodic table are called:
A. Halogens
B. Noble gases
C. Alkali metals
D. Chalcogens
Answer: A. Halogens
Explanation: Group 17 elements are known as halogens, characterised by high electronegativity and reactivity, needing one more electron for a stable configuration.
20. Elements in Group 18 of the periodic table are called:
A. Noble gases
B. Halogens
C. Alkali metals
D. Transition metals
Answer: A. Noble gases
Explanation: Group 18 elements, known as noble gases, have completely filled valence shells, making them largely unreactive.
21. The elements found in the middle block of the periodic table (Groups 3-12) are called:
A. Transition metals
B. Alkali metals
C. Halogens
D. Lanthanides only
Answer: A. Transition metals
Explanation: Transition metals occupy the central block of the periodic table, characterised by partially filled d-orbitals.
22. The elements placed separately at the bottom of the periodic table, following lanthanum, are called the:
A. Lanthanides
B. Actinides only
C. Transition metals
D. Noble gases
Answer: A. Lanthanides
Explanation: The lanthanides are a series of 14 elements following lanthanum, characterised by the filling of the 4f orbitals.
23. Elements with properties intermediate between metals and non-metals are called:
A. Metalloids
B. Transition metals
C. Noble gases
D. Halogens
Answer: A. Metalloids
Explanation: Metalloids display characteristics of both metals and non-metals, situated along the diagonal dividing line in the periodic table.
24. The s-block elements of the periodic table include Groups:
A. 1 and 2
B. 13 and 14
C. 17 and 18
D. 3 to 12
Answer: A. 1 and 2
Explanation: The s-block consists of Groups 1 and 2, where the valence electrons occupy the s-subshell.
25. The p-block elements of the periodic table include Groups:
A. 13 to 18
B. 1 and 2
C. 3 to 12
D. Only Group 18
Answer: A. 13 to 18
Explanation: The p-block spans Groups 13 through 18, where valence electrons are found in the p-subshell.
26. The d-block elements of the periodic table include Groups:
A. 3 to 12
B. 1 and 2
C. 13 to 18
D. Only lanthanides
Answer: A. 3 to 12
Explanation: The d-block, comprising the transition metals, spans Groups 3 through 12, characterised by filling of d-orbitals.
27. Which element generally has the highest electronegativity on the periodic table?
A. Fluorine
B. Sodium
C. Caesium
D. Helium
Answer: A. Fluorine
Explanation: Fluorine, positioned in the top-right area of the periodic table (excluding noble gases), has the highest electronegativity of all elements.
28. Which element generally has the largest atomic radius on the periodic table?
A. Caesium
B. Fluorine
C. Helium
D. Hydrogen
Answer: A. Caesium
Explanation: Caesium, located in the bottom-left region of the periodic table, has one of the largest atomic radii due to its position far down a group.
29. The periodic trend where properties recur at regular intervals when elements are arranged by atomic number is called:
A. Periodicity
B. Isomerism
C. Isotopy
D. Valency
Answer: A. Periodicity
Explanation: Periodicity refers to the recurring pattern of similar chemical and physical properties observed at regular intervals across the periodic table.
30. Noble gases generally have very high ionisation energies because of their:
A. Completely filled and stable valence electron configuration
B. Very large atomic size
C. Low nuclear charge
D. High reactivity
Answer: A. Completely filled and stable valence electron configuration
Explanation: Since noble gases have a stable, completely filled outer shell, removing an electron requires significantly more energy, resulting in high ionisation energies.
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