The Atom and also Electromagnetic Radiation

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Fundamental Subatomic Particles Electromagnetic Radiation
Light and Other creates 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 number of protons, neutrons, and also electrons in an atom have the right to be determined from a collection of an easy rules.

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

Examples: Let"s determine the variety of protons, neutrons, and electrons in the adhering to isotopes.

12C 13C 14C 14N

The various isotopes that an facet are figured out by creating the mass variety of the atom in the top left corner of the symbol because that the element. 12C, 13C, and also 14C are isotopes that carbon (Z = 6) and therefore contain 6 protons. If the atoms are neutral, they additionally must contain six electrons. The only difference in between these isotopes is the number of neutrons in the nucleus.

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

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

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

Practice trouble 1:

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

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Electromagnetic Radiation

Much that what is known around the structure of the electrons in an atom has been acquired by studying the interaction in between matter and also different forms of electromagnetic radiation. Electromagnetic radiation has some the the properties of both a particle and a wave.

Particles have a identify mass and also they occupy space. Waves have actually no mass and yet they bring energy together they travel with space. In addition to their capacity to bring energy, tide have 4 other properties properties: speed, frequency, wavelength, and also amplitude. The frequency (v) is the number of waves (or cycles) every unit of time. The frequency of a tide 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 interpretations of amplitude and also wavelength. The wavelength (l) is the the smallest distance between repeating clues on the wave. The amplitude of the wave is the distance in between the greatest (or lowest) point on the wave and the facility of heaviness of the wave.


If we measure the frequency (v) of a wave in cycles per second and the wavelength (l) in meters, the product of these two numbers has actually the devices of meters every second. The product that the frequency (v) time the wavelength (l) of a tide is thus the speed (s) in ~ which the wave travels with space.

vl = s

Practice difficulty 2:

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

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Practice trouble 3:

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

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Light and Other creates of Electromagnetic Radiation

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

Visible light has the small band of frequencies and wavelengths in the portion of the electro-magnetic spectrum the our eyes deserve to detect. It includes radiation with wavelengths between about 400 nm (violet) and also 700 nm (red). Since it is a wave, irradiate is bent once it enters a glass prism. Once white irradiate is concentrated on a prism, the light rays of various wavelengths are bent by differing amounts and the light is transformed right into a spectrum that colors. Starting from the side of the spectrum whereby the irradiate is bend by the the smallest angle, the colors are red, orange, yellow, green, blue, and violet.

As we have the right to see native the complying with diagram, the energy brought by light boosts as us go indigenous red to blue throughout the visible spectrum.


Because the wavelength that electromagnetic radiation deserve to be as lengthy as 40 m or as quick as 10-5 nm, the clearly shows spectrum is just a small part of the total selection of electromagnetic radiation.


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

vl = c

As a result, electromagnetic radiation that has a lengthy wavelength has actually a low frequency, and radiation with a high frequency has a short wavelength.

Practice trouble 4:

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