Q 11P - Chemistry: Molecular Nature Of Matter And Change

Question

Question: Using the periodic table to locate each element, write the electron configuration of (a) Ru; (b) Cu; (c) Ni.

Step-by-Step Solution

Answer

The electronic configuration of the elements is:

1. $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{2}3{\mathrm{d}}^{10}4{\mathrm{p}}^{6}5{\mathrm{s}}^{1}4{\mathrm{d}}^7$ or $\left[\mathrm{Kr}\right]5{\mathrm{s}}^{1}4{\mathrm{d}}^7$
2. $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{1}3{\mathrm{d}}^{10}$ or $\left[\mathrm{Ar}\right]4{\mathrm{s}}^{1}3{\mathrm{d}}^{10}$
3. $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{2}3{\mathrm{d}}^8$ or $\left[\mathrm{Ar}\right]4{\mathrm{s}}^{2}3{\mathrm{d}}^8$

Step 1: Electron Configuration

The distribution of electrons in atomic or molecular orbitals of an atom, molecule, or other physical structure is known as electron configuration.

Step 2: Electron configuration of element

(a) Based on the periodic table, Ru has the atomic number of $44$, therefore it has $44$ electrons with electron configuration:

$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{2}3{\mathrm{d}}^{10}4{\mathrm{p}}^{6}5{\mathrm{s}}^{1}4{\mathrm{d}}^7$ or  $\left[\mathrm{Kr}\right]5{\mathrm{s}}^{1}4{\mathrm{d}}^7$

Instead of having a full 5 s orbital, the atom is more stable when there is more unpaired electrons.

 

(b) Based on the periodic table, Cu has the atomic number of $29$, therefore it has $29$ electrons with this electron configuration:

$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{1}3{\mathrm{d}}^{10}$ or $\left[\mathrm{Ar}\right]4{\mathrm{s}}^{1}3{\mathrm{d}}^{10}$ 

The atom is more stable when the d orbital is fully filled, and the 4 s orbital is only half-filled.

 

(c) Based on the periodic table, Ni has the atomic number of $28$, therefore it has $28$ electrons with this electron configuration:

$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{2}3{\mathrm{d}}^8$ or $\left[\mathrm{Ar}\right]4{\mathrm{s}}^{2}3{\mathrm{d}}^8$