What causes the emission of radiant energy that produces characteristic spectral lines?
What causes the emission of radiant energy that produces characteristic spectral lines?
Answer: When electrons move from a higher energy level to a lower one, photons are emitted, and an emission line can be seen in the spectrum. Absorption lines are seen when electrons absorb photons and move to higher energy levels. An atom in its lowest energy level is in the ground state.
What causes line spectra?
Spectral lines are produced by transitions of electrons within atoms or ions. As the electrons move closer to or farther from the nucleus of an atom (or of an ion), energy in the form of light (or other radiation) is emitted or absorbed.…
How do spectral lines provide evidence for the existence of energy levels?
As the charge on the nucleus increases so the energy required to remove the electron increases. Spectral lines give evidence of electrons moving from one energy level to another within the atom. Successive ionisations of an atom suggest that there are energy shells with large energy differences between them.
How are atoms able to produce the above spectral lines?
The energy levels of an ionized atom are entirely different from those of the same atom when it is neutral. Each time an electron is removed from the atom, the energy levels of the ion, and thus the wavelengths of the spectral lines it can produce, change.
Which element produces the largest number of spectral lines?
Mercury
What do spectral lines tell us?
From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star. The spectral line also can tell us about any magnetic field of the star. The width of the line can tell us how fast the material is moving. We can learn about winds in stars from this.
Why does hydrogen have so many spectral lines?
Though a hydrogen atom has only one electron, it contains a large number of shells, so when this single electron jumps from one shell to another, a photon is emitted, and the energy difference of the shells causes different wavelengths to be released… hence, mono-electronic hydrogen has many spectral lines.
How many spectral lines are there?
The electron energy level diagram for the hydrogen atom. He found that the four visible spectral lines corresponded to transitions from higher energy levels down to the second energy level (n = 2). This is called the Balmer series.
How many spectral lines does helium have?
12 lines
Why are there more emission lines for helium than for hydrogen?
Helium has more spectral emission lines than hydrogen does. The difference in emission lines are caused by the fact that helium has more electrons than hydrogen does. Hydrogen has only 1 while helium has 2. With more electrons being excited, more spectral lines will be observed.
Does hydrogen or helium have more energy?
Helium has a structure 1s2. The electron is being removed from the same orbital as in hydrogen’s case. It is close to the nucleus and unscreened. The value of the ionization energy (2370 kJ mol-1) is much higher than hydrogen, because the nucleus now has 2 protons attracting the electrons instead of 1.
What is intensity of spectral lines?
INTENSITY OF SPECTRAL LINES. We may call the intensity of a dark line unity if the light cut off from the background is equal to that of one ten-millionth of a miiimetre, or one Angstrom unit.
What are the factors affecting intensity of spectral lines?
depends on:
- • the transition probability.
- between the two states.
- (selection rules)
- • population of states.
- • in absorption, the sample path length l.
- and concentration c (Beer-Lambert law)
Why are dark spectral lines produced?
When light passes through gas in the atmosphere some of the light at particular wavelengths is scattered resulting in darker bands. These lines came to be known as ‘spectral lines’ and were cataloged by heating common elements until they produced light and measuring the wavelengths emitted.
How are absorption lines formed?
An absorption line is produced when a photon of just the right energy is absorbed by an atom, kicking an electron to a higher energy orbit. The photon had energy = the difference in energy of the energy orbits. Other photons moving through the gas with the wrong energy will pass right on by the atoms in the thin gas.
How do absorption lines work?
Absorption lines occur when an atom, element or molecule absorbs a photon with an energy equal to the difference between two energy levels. This causes an electron to be promoted into a higher energy level, and the atom, element or molecule is said to be in an excited state.
What is the formula for number of spectral lines?
For example, suppose one atom with an electron at energy level 7 (n2=7). That electron can “de-excite” from n2=7 to n1=6,5,4,3,2, or 1. All those transitions give one spectral line for each. Thus, total of 1×6=n1(n2−n1) (foot note 1) spectral lines would be present in the spectrum.
How do you find the maximum number of spectral lines?
Max number of Spectral lines = 6 If n is the quantum number of highest energy level, then the total number of possible spectral line emitted is N = n(n – 1) / 2. The question is about the spectral lines emitted in third excited state hydrogen. Then n = 4 as it is the fourth energy level of hydrogen.
How many maximum spectral lines are possible if electron is present in 4th shell?
4. 3 spectral lines
What is the number of spectral lines in a hydrogen spectrum?
6 spectral lines
Why is the emission spectrum of hydrogen not continuous?
Quick answer: Atomic spectra are continuous because the energy levels of electrons in atoms are quantized. The electrons in an atom can have only certain energy levels. Each packet of energy corresponds to a line in the atomic spectrum. There is nothing between each line, so the spectrum is discontinuous.