it is harder to remove free electron from copper than from sodium. which has higher work function?

To understand why it's harder to remove a free electron from copper than from sodium, we need to delve into the concept of work function, which is essentially the minimum energy required to remove an electron from a solid to a point in vacuum. The work function is influenced by several factors, including the material's atomic structure and the strength of the metallic bonds.

Comparing Work Functions

Copper and sodium are both metals, but they exhibit different properties due to their atomic structures. Copper has a higher work function compared to sodium. This means that it requires more energy to remove an electron from copper than from sodium.

Atomic Structure and Bonding

Let's break this down further:

• Copper (Cu): Copper has an atomic number of 29 and a more complex electron configuration, which includes a filled d-subshell. The presence of these d-electrons contributes to stronger metallic bonding. The electrons in copper are held more tightly due to the effective nuclear charge experienced by the outer electrons, making it harder to remove them.
• Sodium (Na): Sodium, on the other hand, has an atomic number of 11 and a simpler electron configuration. It has only one electron in its outer shell (the 3s orbital), which is relatively loosely bound. This single valence electron is easier to remove, resulting in a lower work function.

Energy Considerations

The work function can be thought of as the energy barrier that an electron must overcome to escape the influence of the atomic nucleus. In copper, the higher work function indicates that the energy barrier is greater due to the stronger attraction between the nucleus and the electrons. In contrast, sodium's lower work function reflects a weaker attraction, making it easier for the outer electron to be removed.

Practical Implications

This difference in work function has practical implications in various applications, such as in electronics and photoelectric devices. For instance, materials with lower work functions are often used in applications where easy electron emission is desired, such as in cathodes for electron tubes or in photovoltaic cells.

Summary

In summary, copper has a higher work function than sodium due to its stronger metallic bonding and more complex electron structure. This results in a greater energy requirement to remove an electron from copper compared to sodium. Understanding these differences is crucial for applications in materials science and engineering.