QUANTUM NUMBERS
Which quantum number specifies the main energy level (shell) in which an electron is most likely to be found?
Principal Quantum Number (n)
What property did Dmitri Mendeleev primarily use to arrange the known elements in his periodic table?
Atomic mass (atomic weight)
As you move from left to right across a period, does the atomic radius generally increase or decrease?
Decrease
Which type of radioactive emission consists of helium nuclei?
A. Alpha (α)
B. Beta (β)
C. Gamma (γ)
D. X-ray
A. Alpha (α)
An electron has the following set of quantum numbers:
What are the possible values of the magnetic quantum number?
l = -2, -1, 0, +1, +2
Complete the table below by identifying the scientist and the basis used for each early attempt to classify the elements.
Classification Attempt | Scientist | Basis
Dobereiner's Triad | ------------ | ------------
Newland's Law of Octaves | ------------ | ------------
Classification Attempt | Scientist | Basis
Dobereiner's Triad | Johann Dobereiner | atomic weight of the middle element was approximately the average of the other two
Newland's Law of Octaves | John Newlands | properties repeated every eighth element.
Which periodic property is defined as the energy required to remove the outermost electron from a gaseous atom?
Ionization Energy
Identify whether the description refers to Alpha (α), Beta (β), or Gamma (γ) radiation.
a. Has the greatest penetrating ability.
b. Can be stopped by a sheet of paper.
c. Consists of high-energy electromagnetic waves.
d. Has the greatest ionizing ability.
a. Gamma
b. Alpha
c. Gamma
d. Alpha
An electron has the following quantum numbers:
(3,1,-1, +1/2)
Determine the electron's:
a. Main energy level
b. Sublevel
c. Spin direction (↑ or ↓)
d. Orbital box for the sublevel
a. 3
b. 3p
c. ↑
d. [↑] [] []
Match each scientist in Column A with the correct contribution in Column B.
Column A
1. Johann Dobereiner
2. John Newlands
3. Dmitri Mendeleev
4. Henry Moseley
Column B
A. Arranged elements by atomic number
B. Left blank spaces for undiscovered elements
C. Law of Octaves
D. Triads
1. D
2. C
3. B
4. A
Fill in the blanks.
a. Atomic radius generally __________ from left to right across a period.
b. Ionization energy generally __________ from top to bottom within a group.
c. Electronegativity generally __________ across a period.
d. Electron affinity generally becomes __________ across a period.
a. decreases
b. decreases
c. increases
d. more negative
A radioactive isotope has a half-life of 8 days.
Determine the percentage of the original radioactive material remaining after each time interval.
a. After 8 days: __________
b. After 16 days: __________
c. After 24 days: __________
d. After 32 days: __________
a. 50%
b. 25%
c. 12.5%
d. 6.25%
The electron configuration of sulfur is:
1s² 2s² 2p⁶ 3s² 3p⁴
Using Hund's Rule and the Pauli Exclusion Principle, determine the complete set of four quantum numbers (n,l,ml,ms) for the last electron added to sulfur.
Arrange the following scientists according to the chronology of their contributions to the development of the periodic table. Write 1 for the earliest and 4 for the latest.
___ Dmitri Mendeleev
___ Henry Moseley
___ Johann Wolfgang Döbereiner
___ John Newlands
3,4,1,2
Element X is located in Period 2, Group 1, while Element Y is located in Period 2, Group 17.
Which element is expected to have the:
a. Larger atomic radius
b. Higher electronegativity
c. Higher ionization energy
a. Element X
b. Element Y
c. Element Y
A 40 g sample of Iodine-131 has a half-life of 8 days. How much of the sample remains after 24 days?
5 g
A newly discovered element has its last electron described by the quantum numbers:
(4,3,+2,+1/2)
Predict:
a. the block of the periodic table where the element belongs,
b. the period where the element belongs
c. whether the electron is likely to be an inner or valence electron
d. exact element
a. d
b. 4
c. inner
d. Zr (4d2)
The discovery of Germanium with properties very close to those predicted for Eka-Silicon served as what kind of evidence for Mendeleev's periodic table?
Validation / Supporting Evidence
A newly discovered element has a very low ionization energy and a large atomic radius. Is this element more likely to behave as a metal or a nonmetal?
Metal
A hospital prepares a 64 mg sample of Technetium-99m for a patient's scan. The radioisotope has a half-life of 6 hours. The hospital requires at least 8 mg of Technetium-99m to produce a clear diagnostic image. If the scan is delayed for 24 hours, how much of the sample will remain? Should the same sample still be used?