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Answer the following questions with reference to the Periodic Table, part of which is shown below - Leaving Cert Chemistry - Question 4 - 2001
Question 4
Answer the following questions with reference to the Periodic Table, part of which is shown below. (i) Which of the elements shown shows behaviour closest to that o... show full transcript
Worked Solution & Example Answer:Answer the following questions with reference to the Periodic Table, part of which is shown below - Leaving Cert Chemistry - Question 4 - 2001
Step 1
Which of the elements shown shows behaviour closest to that of an ideal gas?
Answer
The element that shows behavior closest to that of an ideal gas is Helium (He). This is due to its low atomic mass, minimal intermolecular forces, and non-polar nature, enabling it to behave more ideally compared to heavier gases.
Step 2
Explain (a) why atomic radius decreases going from aluminum to chlorine.
Answer
As we move from aluminum to chlorine across a period in the periodic table, the atomic radius decreases due to the increase in nuclear charge. The number of protons increases, leading to a stronger positive charge that pulls the electrons closer to the nucleus, thus reducing the atomic radius.
Step 3
Explain (b) why atomic radius increases going from nitrogen to phosphorus.
Answer
The atomic radius increases from nitrogen to phosphorus because phosphorus has an additional principal energy level (shell). Even though the nuclear charge increases, the effect of increased distance from the nucleus outweighs this, resulting in a larger atomic radius.
Step 4
Explain (c) why the atomic radii of chromium, copper and zinc are very similar?
Answer
The atomic radii of chromium, copper, and zinc are similar due to their position in the same d-block region of the periodic table. They have a similar effective nuclear charge and similar electron shielding effects due to the filled inner electron shells, leading to comparable atomic sizes.
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Step 8
Explain which of the hydrides would you expect to be polar and give reasons for your choice.
Answer
Among nitrogen (NH3) and phosphorus (PH3), ammonia (NH3) is expected to be polar due to the difference in electronegativity between nitrogen and hydrogen. The greater electronegativity of nitrogen creates a dipole moment, leading to polarity, while phosphorus, being less electronegative, results in largely non-polar bonding.
Step 9
Write the electronic configurations for chromium and copper and explain why these are different.
Answer
The electronic configurations are:
- Chromium: [Ar] 3d⁵ 4s¹
- Copper: [Ar] 3d¹⁰ 4s⁰
Chromium has a half-filled d-subshell which provides extra stability, while copper has a fully filled d-subshell, also contributing to stability.
Step 10
Explain why chromium, copper, and zinc are all classified as d-block elements but only chromium and copper are classified as transition elements.
Answer
Chromium and copper are classified as transition elements because they have partially filled d-orbitals in their elemental forms and can form variable oxidation states. In contrast, zinc, which has a filled d-orbital, does not exhibit variable oxidation states and is therefore not classified as a transition element.