Question
What is the correct labelling of the blocks of the periodic table?
▶️Answer/Explanation
Markscheme: D
The periodic table is traditionally divided into four blocks based on the electron configurations of the elements. These blocks are labeled as follows:
1. s-block: The first two groups (Group 1 and Group 2, including helium) are part of the s-block. Elements in the s-block have their outermost electrons in s-orbitals.
2. p-block: Groups 13 to 18 make up the p-block. Elements in the p-block have their outermost electrons in p-orbitals.
3. d-block: The transition metals, which constitute Groups 3 to 12, form the d-block. Elements in the d-block have their outermost electrons in d-orbitals.
4. f-block: The inner transition metals, which include the lanthanides and actinides, form the f-block. These are placed separately at the bottom of the periodic table. The f-block is often further divided into the lanthanides (rare earth elements) and the actinides. The electronic configurations of these elements involve the filling of f-orbitals.
These labels are based on the way electrons are added to atomic orbitals as you move across a period and down a group in the periodic table. The s, p, d, and f designations correspond to different types of atomic orbitals.
Question
What can be deduced from the period number of an element?
I. Highest occupied energy level
II. Number of sub-levels in the outer shell
III. Number of outer electrons
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
▶️Answer/Explanation
Markscheme: A
The period number of an element corresponds to the highest occupied energy level (shell) of its electrons. Therefore, from the period number, you can deduce:
I. Highest occupied energy level – Yes, this is correct.
II. Number of sub-levels in the outer shell – The period number alone does not provide information about the number of sub-levels in the outer shell. This information is related to the specific electron configuration of the element.
III. Number of outer electrons – The period number can give you a rough idea of the number of outer electrons. For elements in a given period, the outer electrons are found in the same principal energy level. However, the specific number of outer electrons depends on the element’s position within the period.
Therefore, the correct answer is A. I and II only.
Question
Which compound is an aromatic ester?
▶️Answer/Explanation
Markscheme: B
An aromatic ester is a type of chemical compound that contains an aromatic (benzene-like) ring and an ester functional group. The ester functional group is characterized by the presence of a carbonyl group (C=O) bonded to an oxygen atom, and an alkyl (or aryl) group bonded to the oxygen. The general structure of an ester is R-COO-R’, where R and R’ are organic groups.
In the case of an aromatic ester, at least one of the organic groups attached to the carbonyl carbon is an aromatic ring. Aromatic rings are characterized by having a cyclic, planar structure with alternating single and double bonds, and they often exhibit a high degree of stability.
A. This structure represents a carboxylic acid (RCOOH), not an ester.
B. This structure represents an aromatic ester. The carbonyl carbon is bonded to an oxygen atom and an aromatic ring.
C. This structure represents an aliphatic ester, not an aromatic ester.
D. This structure represents a molecule with an aldehyde group and an alcohol group, not an ester.
So, the correct choice for an aromatic ester is option B.
Question
Which correctly states the strongest intermolecular forces in the compounds below?
Answer/Explanation
Markscheme
B
Examiners report
Question
What are the strongest intermolecular forces between molecules of propanone, CH3COCH3, in the liquid phase?
A. London (dispersion) forces
B. Covalent bonding
C. Hydrogen bonding
D. Dipole–dipole forces
Answer/Explanation
Markscheme
D