Question

Explain how line spectra are used to identify elements and what they indicate about atoms

Answer 1

@musics_life

Answer 2

There are two kinds of atomic spectra or spectrum
1.Absorption Spectrum

A material's absorption spectrum shows the fraction of incident electromagnetic radiation absorbed by the material over a range of frequencies. An absorption spectrum is, in a sense, the opposite of an emission spectrum. Every chemical element has absorption lines at several particular wavelengths corresponding to the differences between the energy levels of its atomic orbitals. For example, an object that absorbs blue, green and yellow light will appear red when viewed under white light. Absorption spectra can therefore be used to identify elements present in a gas or liquid. This method is used in deducing the presence of elements in stars and other gaseous objects which cannot be measured directly.


Absorption spectrum observed by the Hubble Space Telescope
[edit] Explanation
Atoms are defined by the arrangement of electrons in atomic orbitals. An electron in some orbital may be excited to a more energetic orbital by absorbing exactly one photon which has energy equal to the energy difference of the two orbitals.

Molecular states are defined by the molecule's modes of vibration and rotation. These vibrational and rotational modes are quantized, similar to the atomic orbitals, and may be excited by absorbing single photons.

In both the atomic and molecular cases, the excited states do not persist: after some random amount of time, the atoms and molecules revert back to their original, lower energy state. In atoms, the excited electron returns to a lower orbital, emitting a photon. In molecules, the vibrational or rotational mode decays, also emitting a photon.

When this decay occurs, the photon produced is not necessarily emitted in the same direction as the original photon. The most common angle of this has been shown to be about 45 degrees of the original photon[citation needed]. This applies to any situation where gases lie between a light source and an observer: the observer will see gaps in the spectrum of the light corresponding to the wavelengths of the photons which were absorbed. These gaps occur despite the re-emission of photons because the re-emitted photons are equally likely to travel in all directions, and it is statistically unlikely to travel along the original path to the observer. These gaps appear as black lines in an image of the spectrum

2.Emmision Spectrum

The atomic emission spectrum of an element is the set of frequencies of the electromagnetic waves emitted by atoms of that element. Each atom's atomic emission spectrum is unique and can be used to determine if that element is part of an unknown compound.

Light consists of Electromagnetic radiation of different wavelengths. Therefore, when the elements or their compounds are heated either on a flame or by an electric arc they emit energy in form of light. Analysis, of this light, with the help of spectroscope gives us a discontinuous spectrum. A spectroscope or a spectrometer is a instrument which is used for separating the components of light, which have different wavelengths. The spectrum appears in a series of line called line spectrum. This line spectrum is also called the Atomic Spectrum because it originates in the element. Each element has a different atomic spectrum.The production of line spectra by the atoms of an element, indicates that an atom can radiate only certain amount of energy. This leads to the conclusion that electrons cannot have any amount of energy but only a certain amount of energy.

The emission spectrum characteristics of some elements are plainly visible to the naked eye when these elements are heated. For example, when platinum wire is dipped into a strontium nitrate solution and then inserted into a flame, the strontium atoms emit a red color. Similarly, when copper is inserted into a flame, the flame becomes green. These definite characteristics allow elements to be identified by their atomic emission spectrum. Not all lights emitted by the spectrum are viewable to the naked eye, it also includes ultra violet rays and infra red lighting.

The fact that only certain colors appear in an element's atomic emission spectrum means that only certain frequencies of light are emitted. Each of these frequencies are related to energy by the formula:


herein E is energy, h is Planck's constant and ν is the frequency. This concludes that only photons having certain energies are emitted by the atom. The principle of the atomic emission spectrum explains the varied colors in neon signs, as well as chemical flame test results mentioned above.

The frequencies of light that an atom can emit are dependent on states the electrons can be in. When excited, an electron moves to a higher energy level/orbital. When the electron falls back to its ground level the light is emitted.

An emission spectrum is always the inverse of its absorption spectrum

i hope i helped you

Answer 3

Why copy and paste? why?

Answer 4

A spectral line is like a fingerprint that can be used to identify the atoms, elements or molecules present. The presence of spectral lines is explained by quantum mechanics in terms of the energy levels of atoms, ions and molecules. These energy levels depend on the numbers of protons, electrons and neutrons in an atom, and the limited set of configurations in which these elemental particles can exist (the set of quantum numbers). Atoms prefer to be in their ground state, where all of the electrons are located as close to the nucleus as possible. 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. Emission lines occur when the electrons of an excited atom, element or molecule move between energy levels, returning towards the ground state. The spectral lines of a specific element or molecule at rest in a laboratory always occur at the same wavelengths. For this reason, we are able to identify which element or molecule is causing the spectral lines.

Answer 5

because it helps