The Atom and Electromagnetic Radiation

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Fundamental Subatomic Particles Electromagnetic Radiation
Light and Other develops of Electromagnetic Radiation

Particle Symbol Charge Mass
electron e- -1 0.0005486 amu
proton p+ +1 1.007276 amu
neutron no 0 1.008665 amu

The variety of protons, neutrons, and electrons in an atom can be figured out from a collection of simple rules.

The variety of protons in the cell nucleus of the atom is same to the atomic number (Z). The number of electrons in a neutral atom is same to the number of protons. The mass variety of the atom (M) is same to the sum of the number of protons and also neutrons in the nucleus. The number of neutrons is same to the difference between the mass variety of the atom (M) and also the atomic number (Z).

Examples: Let"s identify the number of protons, neutrons, and also electrons in the complying with isotopes.

12C 13C 14C 14N

The different isotopes the an aspect are figured out by creating the mass number of the atom in the upper left edge of the symbol for the element. 12C, 13C, and also 14C are isotopes the carbon (Z = 6) and therefore contain 6 protons. If the atoms are neutral, they likewise must contain 6 electrons. The just difference between these isotope is the variety of neutrons in the nucleus.

12C: 6 electrons, 6 protons, and also 6 neutrons

13C: 6 electrons, 6 protons, and 7 neutrons

14C: 6 electrons, 6 protons, and 8 neutrons

Practice problem 1:

Calculate the number of electrons in the Cl- and also Fe3+ ions.

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Electromagnetic Radiation

Much of what is known about the structure of the electrons in an atom has been derived by researching the interaction between matter and different forms of electromagnetic radiation. Electromagnetic radiation has some of the properties of both a particle and a wave.

Particles have actually a identify mass and also they occupy space. Waves have no mass and also yet they lug energy together they travel with space. In enhancement to their capacity to carry energy, tide have four other properties properties: speed, frequency, wavelength, and also amplitude. The frequency (v) is the variety of waves (or cycles) per unit that time. The frequency that a wave is report in systems of cycles per second (s-1) or hertz (Hz).

The idealized illustration of a wave in the figure listed below illustrates the definitions of amplitude and wavelength. The wavelength (l) is the smallest distance between repeating point out on the wave. The amplitude that the wave is the distance between the greatest (or lowest) point on the wave and the facility of heaviness of the wave.


If we measure the frequency (v) the a tide in cycles per second and the wavelength (l) in meters, the product of these 2 numbers has actually the units of meters every second. The product that the frequency (v) times the wavelength (l) of a wave is as such the rate (s) at which the tide travels through space.

vl = s

Practice problem 2:

What is the rate of a tide that has a wavelength the 1 meter and a frequency the 60 cycles every second?

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Practice trouble 3:

Orchestras in the United claims tune their instruments to an "A" that has a frequency of 440 cycles every second, or 440 Hz. If the speed of sound is 1116 feet per second, what is the wavelength of this note?

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Light and also Other develops of Electromagnetic Radiation

Light is a wave v both electric and also magnetic components. It is therefore a type of electromagnetic radiation.

Visible light consists of the small band that frequencies and also wavelengths in the part of the electro-magnetic spectrum that our eyes can detect. It has radiation v wavelengths between around 400 nm (violet) and also 700 nm (red). Due to the fact that it is a wave, light is bent once it start a glass prism. As soon as white light is focused on a prism, the light rays of various wavelengths room bent by differing quantities and the irradiate is transformed right into a spectrum the colors. Starting from the side of the spectrum whereby the irradiate is bent by the smallest angle, the colors space red, orange, yellow, green, blue, and violet.

As we have the right to see native the adhering to diagram, the energy carried by light rises as us go native red come blue throughout the clearly shows spectrum.


Because the wavelength that electromagnetic radiation have the right to be as lengthy as 40 m or as quick as 10-5 nm, the visible spectrum is only a small portion of the total selection of electromagnetic radiation.


The electromagnetic spectrum has radio and TV waves, microwaves, infrared, clearly shows light, ultraviolet, x-rays, g-rays, and cosmic rays, as displayed in the figure above. These different forms that radiation all travel at the speed of irradiate (c). They differ, however, in your frequencies and wavelengths. The product of the frequency time the wavelength of electromagnetic radiation is always equal to the rate of light.

vl = c

As a result, electromagnetic radiation that has actually a long wavelength has a short frequency, and also radiation with a high frequency has actually a quick wavelength.

Practice trouble 4:

Calculate the frequency the red light that has actually a wavelength the 700.0 nm if the speed of irradiate is 2.998 x 108 m/s.