Question

An isolated atom has a net charge of__________.

Short answer

The net charge of an isolated atom is determined by comparing the number of protons and electrons. A neutral atom with equal protons and electrons has a net charge of \(0\), while an ion with a difference in protons and electrons has a nonzero net charge.

Step-by-step solution

Identify the Number of Protons and Electrons

Determine the number of protons and electrons in the isolated atom. The number of protons can be found using the atomic number of the element the atom belongs to, which can be found in the periodic table. The number of electrons in a neutral atom is equal to its atomic number or the number of protons. To find the number of electrons in an ion, we need to know the charge of the ion (positive or negative) and the number of electrons gained or lost.

Compare Protons and Electrons

Compare the number of protons and electrons in the atom. If the number of protons is equal to the number of electrons, the net charge of the atom is zero. If there are more protons than electrons, the atom has a positive charge equal to the difference between the number of protons and electrons. If there are more electrons than protons, the atom has a negative charge equal to the difference between the number of electrons and protons.

Determine the Net Charge

The net charge of the isolated atom is the difference between the number of protons and electrons, taking into account the sign of the charge (positive or negative). For example, if an atom has 7 protons and 10 electrons, its net charge is -3. If an atom has 12 protons and 9 electrons, its net charge is +3. For a neutral atom with an equal number of protons and electrons, the net charge is 0. The solution for the given exercise is as follows: The net charge of an isolated atom depends on the difference between the number of protons and electrons present in the atom. A neutral atom has a net charge of 0, while an ion has a nonzero net charge.

Key concepts

Atomic Number

The atomic number is a fundamental concept in chemistry and physics, serving as the identity of an element. It is denoted by the letter 'Z' and indicates the number of protons found in the nucleus of an atom.

To comprehend the net charge of an atom, one must first understand the atomic number, as it directly correlates to the number of protons. Protons carry a positive charge, and in a neutral atom, their number is balanced by an equal number of electrons, which have a negative charge. This balance results in a net charge of zero for the atom. To illustrate, the atomic number of hydrogen is 1, meaning it has one proton and, when neutral, one electron. This balanced state defines its lack of net charge.

Protons and Electrons

Understanding the relationship between protons and electrons is crucial for determining an atom's net charge. Protons are positively charged particles in the nucleus of an atom, while electrons are negatively charged particles that orbit the nucleus.

A key point to remember is that the number of protons in an atom is constant and defines the element, whereas the number of electrons can change if the atom gains or loses electrons to form ions. This gain or loss of electrons alters the net charge of the atom. If an atom loses electrons, it has more protons than electrons, resulting in a positive net charge known as a cation. Conversely, gaining electrons leads to a negative net charge, and the atom becomes an anion. For instance, a neutral oxygen atom has 8 protons and 8 electrons, but as an ion with two extra electrons, it has a net charge of -2.

Ions

Ions are atoms, or groups of atoms, that have a net charge due to the loss or gain of electrons. When atoms gain or lose energy, they may shed or acquire electrons, leading to an imbalance between the number of protons and electrons.

An ion with more protons than electrons carries a positive charge and is known as a cation. In contrast, an ion with more electrons than protons carries a negative charge and is called an anion. The charge on an ion is often indicated by a plus (+) or minus (-) sign, with a numeral that represents the number of electrons lost or gained. An example is Na+, which indicates that a sodium atom has lost one electron, resulting in a net positive charge.