Question

The atomic number of \(\mathrm{Ni}\) and \(\mathrm{Cu}\) are 28 and \(29 \mathrm{re}\) spectively. The electronic configuration \(1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2}\) \(3 \mathrm{p}^{6} 3 \mathrm{~d}^{10}\) represents: (a) \(\mathrm{Cu}^{+}\) (b) \(\mathrm{Cu}^{2+}\) (c) \(\mathrm{Ni}^{2+}\) (d) \(\mathrm{Ni}\)

Short answer

The configuration represents \( \mathrm{Ni}^{2+} \).

Step-by-step solution

Determine Electron Count

First, count the total electrons in the given electronic configuration: \(1s^2\), \(2s^2\), \(2p^6\), \(3s^2\), \(3p^6\), \(3d^{10}\). The sum is \(2+2+6+2+6+10=28\) electrons.

Identify the Neutral Atom

Since the configuration sums up to 28 electrons, the neutral atom with atomic number 28 is nickel (Ni). This implies that the configuration must belong to nickel or a form of nickel, such as an ion.

Determine Ion Formation

Given answers suggest ions of nickel and copper. When nickel (Ni) loses two electrons, it forms \( Ni^{2+} \). The normal electronic configuration for neutral nickel is \([Ar] \, 3d^8 \, 4s^2\). Hence removing two electrons to form \(Ni^{2+} \), we get \([Ar] \, 3d^{10}\), matching the given configuration.

Verify Against Options

The electronic configuration we derived \([Ar] \, 3d^{10}\) matches with the configuration of \(Ni^{2+}\). Check the given options, and see that option (c) \(Ni^{2+}\) is the correct match.

Key concepts

Atomic Number

The atomic number is a fundamental property of elements. It represents the number of protons present in the nucleus of an atom. Each element has a unique atomic number, making it an identifying feature. For instance:

• Nickel has an atomic number of 28, meaning every nickel atom contains 28 protons.
• Copper, on the other hand, has an atomic number of 29, with every atom containing 29 protons.

This property not only defines the type of element but also influences the chemical behavior and reactivity of the element. Since atoms are neutral, the number of electrons in a neutral atom equals the atomic number, keeping the balance between positive and negative charges.

Electron Count

Counting electrons in an atom involves understanding its electronic configuration. Electronic configurations represent how electrons are arranged in an atom's orbitals. Each electron's position is dictated by the rules of quantum mechanics. For a given configuration such as:

• \(1s^2\)
• \(2s^2\)
• \(2p^6\)
• \(3s^2\)
• \(3p^6\)
• \(3d^{10}\)

you simply sum the superscript numbers to find the total electron count. Here,

• \(2+2+6+2+6+10 = 28\) electrons are present.

These are the electrons for a neutral nickel atom, matching its atomic number of 28.

Ion Formation

Ion formation involves the loss or gain of electrons by an atom, resulting in a charged particle. Atoms tend to form ions to achieve a more stable electronic configuration.

• If an atom loses electrons, it forms a positive ion or cation.
• If it gains electrons, it forms a negative ion or anion.

For nickel (Ni), forming a common cation like \(Ni^{2+}\) involves losing two electrons. The loss is typically from the outermost orbitals, transforming the electron configuration from \([Ar] \, 3d^8 \, 4s^2\) to \([Ar] \, 3d^{10}\). This new configuration matches the stable, filled \(3d\) orbitals.

Nickel

Nickel is a transition metal located in the 10th group of the periodic table. It's known for its lustrous appearance and resistance to corrosion. Chemically, nickel typically displays a variety of oxidation states, the most common being +2.

• Neutral nickel has the electronic configuration \([Ar] \, 3d^8 \, 4s^2\).
• In this state, it is flexible in forming chemical bonds, especially in alloys.

Nickel's atomic number is 28, corresponding to its total protons and under normal conditions, its electron count as well. The versatility in its electronic structure allows it to efficiently conduct electricity and heat, making nickel invaluable in industrial applications.

Nickel Ions

Nickel ions form when nickel atoms lose electrons, typically forming the \(Ni^{2+}\) ion. This form is particularly stable and common in various chemical reactions and compounds. The process:

• Starts with neutral nickel: \([Ar] \, 3d^8 \, 4s^2\).
• When losing two electrons, usually from the \(4s\) orbital first, the configuration becomes \([Ar] \, 3d^{10}\).
• Leading to the formation of \(Ni^{2+}\).

The \(3d^{10}\) configuration is quite stable due to filled \(d\) orbitals, contributing to nickel's widespread use in electroplating and as catalysts. As you see, mastering electron behavior gives insight into the properties of nickel ions.