Question

For each of the following processes that show the formation of ions, complete the process by indicating the number of electrons that must be gained or lost to form the ion. Indicate the total number of electrons in the ion, and in the atom from which it was made. a. \(\mathrm{Al} \rightarrow \mathrm{Al}^{3+}\) b. \(\mathrm{S} \rightarrow \mathrm{S}^{2-}\) c. \(\mathrm{Cu} \rightarrow \mathrm{Cu}^{+}\) \(\mathrm{d} . \mathrm{F} \rightarrow \mathrm{F}^{-}\) e. \(\mathrm{Zn} \rightarrow \mathrm{Zn}^{2+}\) \(\mathrm{f} . \mathrm{P} \rightarrow \mathrm{P}^{3-}\)

Short answer

a. Aluminum loses 3 electrons to form \(\mathrm{Al}^{3+}\) ion with 10 electrons. Neutral aluminum atom has 13 electrons. b. Sulfur gains 2 electrons to form \(\mathrm{S}^{2-}\) ion with 18 electrons. Neutral sulfur atom has 16 electrons. c. Copper loses 1 electron to form \(\mathrm{Cu}^{+}\) ion with 28 electrons. Neutral copper atom has 29 electrons. d. Fluorine gains 1 electron to form \(\mathrm{F}^{-}\) ion with 10 electrons. Neutral fluorine atom has 9 electrons. e. Zinc loses 2 electrons to form \(\mathrm{Zn}^{2+}\) ion with 28 electrons. Neutral zinc atom has 30 electrons. f. Phosphorus gains 3 electrons to form \(\mathrm{P}^{3-}\) ion with 18 electrons. Neutral phosphorus atom has 15 electrons.

Step-by-step solution

1. Identify the atomic number

Locate the element Al (aluminum) on the periodic table and find its atomic number (13). This number represents the number of protons and electrons in a neutral aluminum atom.

2. Determine the number of electrons lost

Since aluminium ion has a charge of +3, it has lost 3 electrons to form the \(\mathrm{Al}^{3+}\) ion.

3. Calculate the total number of electrons in the ion

Subtract the 3 lost electrons from the initial electron count (13). This leaves 10 electrons in the \(\mathrm{Al}^{3+}\) ion. b. \(\mathrm{S} \rightarrow \mathrm{S}^{2-}\)

1. Identify the atomic number

Locate the element S (sulfur) on the periodic table and find its atomic number (16).

2. Determine the number of electrons gained

Since sulfur ion has a charge of -2, it has gained 2 electrons to form the \(\mathrm{S}^{2-}\) ion.

3. Calculate the total number of electrons in the ion

Add the 2 gained electrons to the initial electron count (16). This results in 18 electrons in the \(\mathrm{S}^{2-}\) ion. c. \(\mathrm{Cu} \rightarrow \mathrm{Cu}^{+}\)

1. Identify the atomic number

Locate the element Cu (copper) on the periodic table and find its atomic number (29).

2. Determine the number of electrons lost

Since copper ion has a charge of +1, it has lost 1 electron to form the \(\mathrm{Cu}^{+}\) ion.

3. Calculate the total number of electrons in the ion

Subtract the 1 lost electron from the initial electron count (29). This leaves 28 electrons in the \(\mathrm{Cu}^{+}\) ion. \(\mathrm{d} . \mathrm{F} \rightarrow \mathrm{F}^{-}\)

1. Identify the atomic number

Locate the element F (fluorine) on the periodic table and find its atomic number (9).

2. Determine the number of electrons gained

Since fluorine ion has a charge of -1, it has gained 1 electron to form the \(\mathrm{F}^{-}\) ion.

3. Calculate the total number of electrons in the ion

Add the 1 gained electron to the initial electron count (9). This results in 10 electrons in the \(\mathrm{F}^{-}\) ion. e. \(\mathrm{Zn} \rightarrow \mathrm{Zn}^{2+}\)

1. Identify the atomic number

Locate the element Zn (zinc) on the periodic table and find its atomic number (30).

2. Determine the number of electrons lost

Since zinc ion has a charge of +2, it has lost 2 electrons to form the \(\mathrm{Zn}^{2+}\) ion.

3. Calculate the total number of electrons in the ion

Subtract the 2 lost electrons from the initial electron count (30). This leaves 28 electrons in the \(\mathrm{Zn}^{2+}\) ion. \(\mathrm{f} . \mathrm{P} \rightarrow \mathrm{P}^{3-}\)

1. Identify the atomic number

Locate the element P (phosphorus) on the periodic table and find its atomic number (15).

2. Determine the number of electrons gained

Since phosphorus ion has a charge of -3, it has gained 3 electrons to form the \(\mathrm{P}^{3-}\) ion.

3. Calculate the total number of electrons in the ion

Add the 3 gained electrons to the initial electron count (15). This results in 18 electrons in the \(\mathrm{P}^{3-}\) ion.

Key concepts

Electron Transfer

The formation of ions through electron transfer is a fundamental concept in chemistry. Ions are atoms or molecules with a net electrical charge due to the loss or gain of one or more electrons. When an atom loses electrons, which are negatively charged, it becomes a positively charged ion, known as a cation. Conversely, when an atom gains electrons, it becomes a negatively charged ion, known as an anion.

For example, an aluminum atom (Al) becomes an Al³⁺ ion upon losing three electrons. This electron transfer process is crucial in many chemical reactions, including the formation of salts and the conductance of electricity in ionic compounds.

Visualizing Electron Transfer

Imagine a neutral atom like a room with an equal number of positive (protons) and negative (electrons) charges. Losing electrons is like removing some negative charges from the room, making the room positive. Gaining electrons adds more negative charges, thus making the room negative. This process alters the electrical neutrality of the atom, creating an ion.

Ion Charge

The ion charge is the electric charge an ion carries and it indicates the difference in the number of protons and electrons within an ion. A neutral atom has the same number of protons and electrons. During ion formation, this balance is disrupted.

An aluminium ion, Al³⁺, indicates that three more protons than electrons are present, therefore it has a +3 charge. Sulfur, when it becomes an S^2- ion, has gained two electrons, indicating a charge of -2. This information helps us to understand the reactivity and bonding behavior of elements.

Significance of Ion Charge

The charge of an ion determines the electrostatic interactions it can have. For instance, ions with opposite charges attract each other and can form ionic bonds, leading to the creation of ionic compounds.

Periodic Table Atomic Number

The periodic table atomic number represents the number of protons in the nucleus of an atom, and it is a crucial identifier for elements. Since atoms are electrically neutral, the atomic number also tells us the number of electrons in an uncharged atom.

To determine the ion's electron count, knowing the atomic number is the first step. For instance, the atomic number of phosphorus (P) is 15, which means a neutral phosphorus atom has 15 electrons. When the P atom transforms into a P^3- ion by gaining three electrons, the electron count changes accordingly.

Utilizing the Atomic Number

By referring to the periodic table, we can easily locate an element's atomic number and use it as a reference point for understanding ion formation, predicting ion charges, and deducing the resulting changes in electron count.

Electron Count

The electron count of an atom or ion dictates its chemical properties and is directly influenced by electron transfer during ion formation. The electron count in a neutral atom is equal to its atomic number, while the electron count in ions varies due to the gain or loss of electrons.

For example, a copper atom (Cu) has an atomic number of 29, meaning a neutral copper atom has 29 electrons. When it loses one electron to become a Cu⁺ ion, the electron count becomes 28. Tracking these changes is essential in predicting the behavior of ions in chemical reactions and the properties of the substances they form.

Understanding Electron Count Changes

The change in electron count is what gives ions their charge; cations have fewer electrons than protons, resulting in a positive charge, while anions have more electrons than protons, giving them a negative charge.