Question

Must all atoms with an odd atomic number be paramagnetic? Must all atoms with an even atomic number be diamagnetic? Explain.

Short answer

No, not all atoms with an odd atomic number must be paramagnetic nor must all atoms with an even atomic number be diamagnetic. Whether an atom is paramagnetic or diamagnetic is not primarily determined by whether its atomic number is odd or even, but by whether it has unpaired electrons (paramagnetic) or all electrons are paired (diamagnetic).

Step-by-step solution

Understanding Atomic Number and Electron Configuration

Atomic number specifies the number of protons in an atom, and in an atom that is electrically neutral, this equals the number of electrons as well. Since the atomic number determines the electron configuration of an atom, we now need to assess if an odd or even atomic number directly relate to paramagnetic or diamagnetic properties.

Analyzing Paramagnetic Atoms

Paramagnetism occurs when an atom possesses one or more unpaired electrons. This does not necessarily relate to the atomic number being odd. For instance, helium (He) with an atomic number 2, and Neon (Ne) with atomic number 10 both have all their atomic orbitals fully filled and shows no unpaired electron, hence they are not paramagnetic.

Analyzing Diamagnetic Atoms

Diamagnetism is displayed by atoms that have all their electrons paired up in their atomic orbitals, and hence, are repelled by a magnetic field. This doesn't directly relate to the atomic number being even. Take for example, lithium (Li) with an atomic number of 3 and oxygen (O) with an atomic number of 8 both have paired electrons and are diamagnetic.

Key concepts

Atomic Number

The atomic number of an element is a fundamental property that serves to distinguish one element from another on the periodic table. It is defined as the number of protons present in the nucleus of an atom. For a neutral atom, the atomic number also equals the number of electrons. These electrons and their arrangement can greatly influence an atom's chemical properties.
In terms of understanding magnetic properties like paramagnetism and diamagnetism, the atomic number helps determine the electron configuration of an atom. The electron configuration, essentially a map of how these electrons are distributed across different energy levels and orbitals, dictates whether there are unpaired electrons, which ultimately influences whether an atom is paramagnetic or diamagnetic. Therefore, knowing the atomic number is the first step in predicting the magnetic behavior of an element.

Electron Configuration

Electron configuration is like the blueprint of an atom that tells us where electrons reside within the atom. Each electron configuration follows specific rules to fill the various orbitals in order of increasing energy. The most common rule is the Aufbau principle, which guides electrons to fill orbitals starting from the lowest available energy level.
Other rules involve Hund’s rule, stating that electrons will fill empty orbitals before pairing up in the same orbital, and the Pauli exclusion principle, which maintains that no two electrons in an atom can have exactly the same set of quantum numbers. Understanding electron configurations allows us to predict and explain the chemical and physical properties of elements, including their paramagnetism and diamagnetism.
For example, knowing whether an atom will have unpaired electrons hinges on its electron configuration. Consequently, it is the configuration rather than just the atomic number that helps tell whether an atom will be attracted to or repelled by a magnetic field.

Unpaired Electrons

Unpaired electrons are the key players in determining the magnetic properties of an atom. Paramagnetism arises when there are unpaired electrons within an atom—which means that not all electrons are paired within their respective orbitals. These unpaired electrons have a magnetic moment and cause the atom to be weakly attracted to a magnetic field.
Take, for instance, oxygen, which despite having an even atomic number, is paramagnetic due to having two unpaired electrons. On the other hand, diamagnetism occurs when every electron in an atom is paired. With all electrons paired, their magnetic fields cancel each other out, resulting in atoms that are slightly repelled by a magnetic field.

• Atoms with only paired electrons and no unpaired ones are considered diamagnetic.
• It’s the presence of unpaired electrons, rather than any characteristic of the atomic number being odd or even, that determines an element's paramagnetic or diamagnetic nature.

Unpaired electrons can be understood as the driving factor behind an element's magnetic responsiveness, highlighting the importance of analyzing electron configurations.