Question
Which metals are considered to be transition elements?
I. Ti
II. Zn
III. Fe
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
▶️Answer/Explanation
B
Transition elements (also known as transition metals) are elements that have partially filled d orbitals. IUPAC defines transition elements as an element having a d subshell that is partially filled with electrons, or an element that has the ability to form stable cations with an incompletely filled d orbital.
In general, any element which corresponds to the d-block of the modern periodic table (which consists of groups 3-12) is considered to be a transition element. Even the f-block elements comprising the lanthanides and the actinides can be considered as transition metals.
However, since the f-block elements have incompletely filled f-orbitals, they are often referred to as inner transition elements or inner transition metals.
It is important to note that the element’s mercury, cadmium, and zinc are not considered transition elements because of their electronic configurations, which corresponds to (n-1)d10 ns2.
These elements have completely filled d orbitals in their ground states and even in some of their oxidation states. One such example is the +2 oxidation state of mercury, which corresponds to an electronic configuration of (n-1)d10.
Hence, Ti and Fe are transition elements here.
Question
What is the correct electron configuration of the \({\text{C}}{{\text{u}}^ + }\) ion?
A. \({\text{[Ar] 3}}{{\text{d}}^{\text{9}}}{\text{ 4}}{{\text{s}}^{\text{1}}}\)
B. \({\text{[Ar] 3}}{{\text{d}}^{\text{7}}}{\text{ 4}}{{\text{s}}^{\text{2}}}\)
C. \({\text{[Ar] 3}}{{\text{d}}^{{\text{10}}}}\)
D. \({\text{[Ar] 3}}{{\text{d}}^{\text{8}}}{\text{ 4}}{{\text{s}}^{\text{1}}}\)
▶️Answer/Explanation
C
Half-filled and fully filled subshell have got extra stability. This give us the (correct) configuration of Cu: 1s22s22p63s23p63d104s1
For the Cu+ ion we remove one electron from 4s1 leaving us with Cu+ : 1s22s22p63s23p63d10. or \({\text{[Ar] 3}}{{\text{d}}^{{\text{10}}}}\)
Question
Which species has the electron configuration of \({\text{1}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{p}}^{\text{6}}}{\text{3}}{{\text{s}}^{\text{2}}}{\text{3}}{{\text{p}}^{\text{6}}}{\text{3}}{{\text{d}}^{\text{8}}}\)?
A. Ni
B. \({\text{N}}{{\text{i}}^{2 + }}\)
C. Fe
D. \({\text{C}}{{\text{u}}^{2 + }}\)
▶️Answer/Explanation
B
Here, 2 electrons from the 4s orbital are removed. It means the specie has 2+ charge and 26 electrons. The neutral element would have 28 electrons. The element is Ni.
Configuration of Ni : 1s22s22p63s23p63d84s2
Configuration of \({\text{N}}{{\text{i}}^{2 + }}\) : \({\text{1}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{p}}^{\text{6}}}{\text{3}}{{\text{s}}^{\text{2}}}{\text{3}}{{\text{p}}^{\text{6}}}{\text{3}}{{\text{d}}^{\text{8}}}\).
Question
Which compounds have an ionic lattice structure in the solid state?
I. Silicon dioxide
II. Sodium fluoride
III. Ammonium nitrate
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
▶️Answer/Explanation
C
In the majority of silicon dioxides, the silicon atom shows tetrahedral coordination, with four oxygen atoms surrounding a central Si atom (see 3-D Unit Cell). Thus, SiO2 forms 3-dimensional network solids in which each silicon atom is covalently bonded in a tetrahedral manner to 4 oxygen atoms. Hence, silicon dioxide has covalent lattice structure.
Sodium fluoride and Ammonium nitrate have ionic lattice structures in the solid state.
Question
Which electron configuration is that of a transition metal atom in the ground state?
A. [Ne]3s23p64s1
B. [Ar]3d9
C. 1s22s22p63s23p64s23d104p2
D. [Ar]4s13d5
▶️Answer/Explanation
D
D represents Chromium in ground state which is a transition element.