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CHEMISTRY, M1 2014 HSC 35ci

Three electron configurations are presented in the table. For elemental titanium, the ground state is represented by \(\text{I}\), while \(\text{II}\) and \(\text{III}\) are both invalid ground state electron configurations.
 

Write a valid electron configuration for \(\ce{Ti^3+}\).  (2 marks)

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Possible answer structures include:

\(\ce{1s^2 2s^2 2p^6 3s^2 3p^6 3d^1}\)

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Possible answer structures include:

\(\ce{1s^2 2s^2 2p^6 3s^2 3p^6 3d^1}\)

CHEMISTRY, M1 2007 HSC 31ai

The electron spin orbital diagram represents the \(3d\) and \(4s\) electrons for an element in the first transition series.

Identify this element and explain the arrangement of electrons in these sub-shells in terms of the Pauli exclusion principle and Hund's rule.  (3 marks)

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→ The electron configuration of \(3d^{6}\) \(4s^{2}\) is that of Iron (Atomic No. 26). 

→ Hund’s Rule: Every orbital within a sub shell must by singly occupied before an orbital can become doubly occupied.

    • The \(3d\) sub shell has 5 orbitals, therefore for an orbital to contain 2 electrons, there must be a minimum of 6 electrons 

→ Pauli Exclusion Principle: No more than 2 electrons can occupy the same orbital and the 2 electrons in the same orbital must have opposite spin.

    • The orbital within the \(3d\) sub shell containing 2 electrons follows this rule, as does the orbital within the \(4s\) sub shell.
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→ The electron configuration of \(3d^{6}\) \(4s^{2}\) is that of Iron (Atomic No. 26). 

→ Hund’s Rule: Every orbital within a sub shell must by singly occupied before an orbital can become doubly occupied.

    • The \(3d\) sub shell has 5 orbitals, therefore for an orbital to contain 2 electrons, there must be a minimum of 6 electrons 

→ Pauli Exclusion Principle: No more than 2 electrons can occupy the same orbital and the 2 electrons in the same orbital must have opposite spin.

    • The orbital within the \(3d\) sub shell containing 2 electrons follows this rule, as does the orbital within the \(4s\) sub shell.

CHEMISTRY, M1 2008 HSC 32ai

The diagram below shows the ground state electron configuration of two complexes of cobalt in aqueous solution.
 


Identify the block in the periodic table to which cobalt belongs and write the electron configuration of cobalt metal in its ground state.  (2 marks)

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→ Cobalt belongs to the D-block on the periodic table.

→ The electron configuration of Cobalt metal in its ground state is:

\(1s^{2}\)  \(2s^{2}\) \(2p^{6}\) \(3s^{2}\) \(3p^{6}\) \(4s^{2}\) \(3d^{7}\)

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→ Cobalt belongs to the D-block on the periodic table.

→ The electron configuration of Cobalt metal in its ground state is:

\(1s^{2}\)  \(2s^{2}\) \(2p^{6}\) \(3s^{2}\) \(3p^{6}\) \(4s^{2}\) \(3d^{7}\)

CHEMISTRY, M1 2009 HSC 30bii

Write the full electron configurations for a \(\ce{Ca}\) atom in the ground state, an excited \(\ce{Ca}\) atom and a \( \ce{Ca}^{+}\) ion.  (2 marks)

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\(\ce{Ca}\) atom: \(\ce{1s^2 2s^2 2p^6 3s^2 3p^6 4s^2}\)

\(\ce{Ca}\) atom (excited): \(\ce{1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 4p^1}\)

\(\ce{Ca^+}\) atom: \(\ce{1s^2 2s^2 2p^6 3s^2 3p^6 4s}\)

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\(\ce{Ca}\) atom:  \(\ce{1s^2 2s^2 2p^6 3s^2 3p^6 4s^2}\)

\(\ce{Ca}\) atom (excited):  \(\ce{1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 4p^1}\)

\(\ce{Ca^+}\) atom:  \(\ce{1s^2 2s^2 2p^6 3s^2 3p^6 4s}\)

CHEMISTRY, M1 2011 HSC 36bii

Explain the fact that Group I and Group II metal ions have one oxidation state while the transition metals often have multiple oxidation states.  (3 marks)

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→ Group I and II metals lose one or two ‘s’ valence shell electrons easily to acquire a noble gas electron configuration.

→ Removal of further electrons is difficult.

→ Thus Group I metals lose one electron and Group II metals lose two electrons to form +1 and +2 cations respectively.

→ Transitions elements lose ‘d’ shell electrons, to obtain a variety of oxidation states.

CHEMISTRY, M1 2011 HSC 36bi

Identify ONE cation and ONE anion that can be represented by the electron configuration \( \ce{1 s^2 2 s^2 2 p^6 3 s^2 3 p^6} \).  (2 marks)

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Answers could include one of the following:

\(\ce{K+, Cl-}\)

\(\ce{Ca^{2+}, S^{2-}}\)

\(\ce{Sc^{3+}, P^{3-}}\)

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Answers could include one of the following:

\(\ce{K+, Cl-}\)

\(\ce{Ca^{2+}, S^{2-}}\)

\(\ce{Sc^{3+}, P^{3-}}\)

CHEMISTRY, M1 2013 HSC 35bii

An atom has FIVE valence electrons in its \(d\) orbital. Using an orbital diagram of the valence shell of the atom, explain how Hund's rule determines the electronic configuration.  (3 marks)

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→ Hund’s rule states that every orbital in a subshell is occupied with one electron before any orbital is doubly occupied.

→ In this example Hund’s rule is illustrated by the \(3d\) sub-shell having 5 electrons in 5 different orbitals.

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→ Hund’s rule states that every orbital in a subshell is occupied with one electron before any orbital is doubly occupied.

→ In this example Hund’s rule is illustrated by the \(3d\) sub-shell having 5 electrons in 5 different orbitals.