Question

An electron in the lithium atom is in the thi?d energy level. Then, which of the following is falsc? (1) The electron is in the excited state. (2) The atom can emit light. (3) The atom will decay due to radioactivity. (4) This implies no change in its nucleus.

Short answer

Statement 3 is false.

Step-by-step solution

Understand the Problem

An electron is in the third energy level of a lithium atom. Determine which statement about the atom's state and behavior is false.

Analyze Each Statement

Evaluate each of the given statements individually to see if it accurately describes an electron in the third energy level.

Evaluate Statement 1

Statement 1: 'The electron is in the excited state.' This is true because any electron in the third energy level is above the ground state and thus in an excited state.

Evaluate Statement 2

Statement 2: 'The atom can emit light.' This is true because an excited electron can transition to a lower energy level, emitting a photon (light) in the process.

Evaluate Statement 3

Statement 3: 'The atom will decay due to radioactivity.' Lithium is generally stable and does not commonly exhibit radioactive decay, especially through the change of electron energy levels.

Evaluate Statement 4

Statement 4: 'This implies no change in its nucleus.' This is true because a change in electron energy levels does not affect the nucleus.

Identify the False Statement

Based on the analysis, Statement 3 is false because the excited state of an electron does not cause the lithium atom to decay radioactively.

Key concepts

Energy Levels

Energy levels are specific regions around an atom's nucleus where electrons can orbit.
Electrons in these levels have distinct amounts of energy. The closest level to the nucleus is called the ground state and has the lowest energy.
When an electron absorbs energy, it can jump to a higher energy level, which we call the excited state.
For example, in a lithium atom, an electron in the third energy level has absorbed energy and moved up from its ground state.

Excited State

An excited state occurs when an electron absorbs enough energy to jump from a lower energy level to a higher one.
This state is temporary because the electron prefers to be in the lowest possible energy state (ground state).
The energy absorbed can come from various sources like heat, light, or electricity.
In our example, the electron in the third energy level of a lithium atom is in an excited state.

Radioactive Decay

Radioactive decay is a process where an unstable atomic nucleus loses energy by emitting radiation.
This process results in the transformation of the original atom into a different element or isotope.
However, changes in the energy levels of electrons do not usually cause radioactive decay because they do not affect the nucleus.
For instance, lithium is typically stable and not prone to radioactive decay, so a change in the energy level of an electron will not cause the atom to decay.

Photon Emission

Photon emission happens when an excited electron returns to a lower energy level.
The energy difference between the two levels is released as a photon (a particle of light).
The color of the emitted light depends on the energy difference between the levels.
For example, in the lithium atom, if an electron moves from the third energy level down to the second or first level, it emits a photon.