Ions: Videos & Practice Problems

Ions are atoms that have gained or lost electrons, resulting in a net electrical charge. When an atom loses electrons, it becomes a cation, which is a positively charged ion. Conversely, when an atom gains electrons, it becomes an anion, a negatively charged ion. The atomic number, indicating the number of protons, remains unchanged during ion formation. For example, a neutral boron atom with five protons and five electrons becomes a boron cation with a +3 charge after losing three electrons. Similarly, an oxygen atom with eight protons and eight electrons becomes an oxygen anion with a -2 charge upon gaining two electrons. Understanding ion formation is crucial as it underpins many chemical reactions, including the formation of compounds and the principles of electrochemistry.

Atoms vs. Ions

Atoms are neutral entities characterized by an equal number of protons and electrons. However, when the balance between protons and electrons is disrupted, ions are formed. Ions arise from the loss or gain of electrons by an element. When an element loses electrons, it transforms into a positively charged ion known as a cation. This occurs because the loss of negatively charged electrons results in a net positive charge. Conversely, when an element gains electrons, it becomes a negatively charged ion called an anion, as the addition of negative electrons increases the overall negative charge.

It is essential to remember that cations are positively charged ions, while anions are negatively charged ions. A related concept is isoelectronic, which refers to different elements or ions that possess the same number of electrons. The key distinction between atoms and ions lies in their charge: atoms maintain an equal number of protons and electrons, while ions exhibit a difference in these quantities due to the gain or loss of electrons. Understanding this difference is crucial when studying the behavior and properties of ions in various chemical contexts.

Ion Formation

Understanding the formation of positive and negative ions begins with the basic structure of atoms. For instance, consider boron, represented as ¹¹₅B. Here, the mass number (11) indicates the total number of protons and neutrons, while the atomic number (5) signifies the number of protons. In the case of boron, the atomic number reveals that it has 5 protons, which corresponds to its position on the periodic table. Since a neutral atom has an equal number of protons and electrons, boron also contains 5 electrons. The charges balance out, resulting in a neutral state: +5 (from protons) and -5 (from electrons) sum to 0.

When examining the ionization of boron, if it loses 3 electrons, it retains its 5 protons but now has only 2 electrons remaining. This results in a net charge of +3, denoted as 3⁺ or +3, indicating that boron has become a positively charged ion, or cation. The convention for writing the charge can vary, so it's advisable to confirm with your instructor whether they prefer the charge written before or after the number.

Next, consider oxygen, represented as ¹⁶₈O. With an atomic number of 8, oxygen has 8 protons and, in its neutral state, also 8 electrons. This balance results in a charge of 0. However, if oxygen gains 2 additional electrons, it now has 10 electrons while still maintaining its 8 protons. The resulting charge calculation is +8 (from protons) and -10 (from electrons), leading to a net charge of -2, represented as 2^- or -2. This indicates that oxygen has become a negatively charged ion, or anion.

In summary, the formation of ions is a result of the loss or gain of electrons. Losing electrons results in a positive charge, while gaining electrons results in a negative charge. Understanding these concepts is crucial for determining the charges and subatomic particle counts for various ions, which is foundational in the study of chemistry.

Cation Subatomic Particles Example

To determine the number of protons, neutrons, and electrons in a cation, we start by identifying key values from the atomic notation. In this case, the atomic number (Z) is 13, which indicates that there are 13 protons in the element. Since this is a cation with a +3 charge, it means that the element has lost 3 electrons. In a neutral atom, the number of protons equals the number of electrons, so a neutral aluminum atom would have 13 electrons. However, due to the +3 charge, the cation has only 10 electrons remaining.

The mass number (A) is given as 27, which represents the total number of protons and neutrons in the atom. To find the number of neutrons, we can use the formula:

$N=A-Z$

Substituting the known values, we have:

$N=27-13$

This calculation yields 14 neutrons. Therefore, we have:

• Protons: 13
• Neutrons: 14
• Electrons: 10

In summary, the cation has 13 protons, 14 neutrons, and 10 electrons, confirming that the correct answer is option C. This aligns with the charge of +3, as calculated by the difference between the number of protons and electrons (13 protons - 10 electrons = +3).

Give the correct number of protons, neutrons and electrons for the following isotope:.

• A. 35 protons, 35 neutrons, 81 electrons
• B. 35 protons, 46 neutrons, 36 electrons
• C. 81 protons, 46 neutrons, 82 electrons
• D. 35 protons, 46 neutrons, 34 electrons

Answer: (B)

In which pair are the two species both isoelectronic and isotopic?

• A.
• B.
• C.
• D.

Answer: (B)

One isotope of a metallic element has a mass number of 65 and 35 neutrons in the nucleus. The cation that this atom forms has 28 electrons. What is the symbol of the cation?

• A. ⁶⁵Zn
• B. ⁶⁵Ga³⁺
• C. ⁶⁵Zn²⁺
• D. ⁶⁵Ni²⁺

Answer: (C)

Which of the following is the symbol for the ion with a +4 charge, 30 neutrons and 21 electrons?

• A. ⁵⁵Mn⁴⁺
• B. ⁵¹Cl⁴⁺
• C. ⁵¹Mn⁴⁺
• D. ⁵⁸Ni⁴⁺

Answer: (A)

Here’s what students ask on this topic:

What are ions?

Ions are atoms or molecules that carry an electric charge. This charge results from the loss or gain of electrons, which are negatively charged subatomic particles. When an atom loses one or more electrons, 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.

The process of becoming an ion is called ionization. Ions are essential in various chemical processes and play a crucial role in the function of living organisms. For example, they are key to the conduction of electrical signals in nerve cells and the transport of substances across cell membranes. In the environment, ions contribute to the electrical conductivity of water and the formation of minerals. They are also integral to many technological applications, such as batteries and electrolysis.

How are ions formed?

Ions are formed when atoms gain or lose electrons, resulting in a net electrical charge. Atoms are made up of protons, neutrons, and electrons. Protons have a positive charge, electrons have a negative charge, and neutrons have no charge. Normally, an atom is neutral because the number of protons and electrons is equal, balancing the charges.

However, if an atom loses one or more electrons, it becomes a positively charged ion, known as a cation. This can happen if an atom has a low electron affinity or if it comes into contact with an atom that has a much higher affinity for electrons.

Conversely, if an atom gains extra electrons, it becomes a negatively charged ion, called an anion. This typically occurs when an atom has a high electron affinity and is able to attract electrons from another atom with a lower electron affinity.

The process of ion formation is crucial in many chemical reactions, including the formation of salts from acids and bases and the conduction of electricity in electrolytes.

What are negatively charged ions called?

Negatively charged ions are called anions. In chemistry, an ion is an atom or molecule that has a net electrical charge due to the loss or gain of one or more electrons. Anions are formed when an atom or molecule gains electrons, which results in a negative charge because electrons carry a negative charge. This process is known as electron gain or reduction. The opposite of an anion is a cation, which is a positively charged ion that is formed when an atom or molecule loses one or more electrons. Anions are crucial in various chemical reactions and are commonly found in solutions, such as the electrolytes in batteries or the salts dissolved in water.