The 350th anniversary of Robert Boyle's discovery of the relationship between the pressure and the volume of a fixed mass of gas at constant temperature is commemorated in this Irish stamp issued in 2012 - Leaving Cert Chemistry - Question 5 - 2013

The different flame colors result from the excitation of electrons in metal atoms. When the metal salt is heated, electrons absorb energy, causing them to jump to higher energy levels. When these electrons return to their ground state, they release energy in the form of light. Each metal has unique electron arrangements and energy levels, leading to distinct colors. For example, sodium produces a yellow flame, while copper produces a green flame.

The flame test on lithium chloride typically produces a crimson red color.

To perform a flame test using lithium chloride, a clean platinum or nichrome wire is dipped into a concentrated solution of the salt. The wire is then held in the flame of a Bunsen burner. The color of the flame is observed and recorded.

The 'uncertainty principle' states that it is impossible to know both the exact position and momentum of a particle simultaneously. This principle introduces limits to our observations and measurements in quantum mechanics.

One other factor that contributed to the need for modification of Bohr's theory was the discovery of electron diffraction, which provided evidence for the wave-particle duality of electrons.

An atomic orbital is a region in an atom where there is a high probability of finding an electron. It represents a solution to the Schrödinger equation for electrons in an atom, defining the spatial distribution of electron density.