2.1 Bohr's Atomic Model

State the four postulates used by Neils Bohr to explain the nature of atom. 1. Electrons circulate around the nucleus in certain orbits / energy levels.2. Only orbits with definite energies are permitted for electrons in an atom. Energy of electrons is quantized at the specific energy level.3. No energy is absorbed or released when electrons circulates in an orbit.4. Energy is emitted or absorbed when electrons change from one energy level to another. This energy is called photons. Differentiate between a ground state and an excited state. Ground state is the most stable and lowest energy state of an atom.An excited state is the state that has higher energy than the ground state. Differentiate between continuous spectrum and line spectrum. Continuous spectrum is the spectrum with all wavelengths of light are present.Line spectrum is the spectrum with a series of discrete lines with certain wavelength. Example : emission spectrum of hydrogen atom. Describe the formation of the line spectrum of hydrogen atom. 1. Hydrogen atom at ground state absorbs energy and its electron excites to a higher energy level.2. At excited state, the electron is unstable.3. The electrons falls to a lower enegy level and emits energy in the form of photons with specific wavelength and frequency.4. Since the energy of photon is quantized, line spectrum is formed.