The Atom and 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 variety of protons, neutrons, and also electrons in one atom deserve to be figured out from a set of an easy rules.

The number of protons in the cell core 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 number of the atom (M) is same to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is same to the difference between the mass number of the atom (M) and the atom number (Z).

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


12C 13C 14C 14N

The various isotopes the an element are figured out by composing the mass number of the atom in the top left edge of the symbol because that the element. 12C, 13C, and 14C are isotopes that carbon (Z = 6) and therefore contain six protons. If the atoms space neutral, they also must contain six electrons. The only difference 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 difficulty 1:

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

Click right here to inspect your answer come Practice trouble 1


Electromagnetic Radiation

Much of what is known around the framework of the electron in one atom has been obtained by examining the interaction in between matter and also different develops of electromagnetic radiation. Electromagnetic radiation has some that the properties of both a particle and a wave.

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

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

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If us measure the frequency (v) of a tide in cycles per second and the wavelength (l) in meters, the product of these two numbers has actually the systems of meters per second. The product that the frequency (v) times the wavelength (l) the a tide is therefore the speed (s) in ~ which the wave travels v space.

vl = s


Practice trouble 2:

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

Click right here to check your answer come Practice problem 2


Practice problem 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 rate of sound is 1116 feet per second, what is the wavelength of this note?

Click here to check your answer to Practice problem 3

Click here to see a systems to Practice problem 3




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Light and also Other forms of Electromagnetic Radiation

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

Visible light contains the small band of frequencies and also wavelengths in the section of the electro-magnetic spectrum that our eyes can detect. It includes radiation with wavelengths between about 400 nm (violet) and also 700 nm (red). Due to the fact that it is a wave, light is bent once it enters a glass prism. Once white light is concentrated on a prism, the light rays of different wavelengths space bent by differing quantities and the irradiate is transformed right into a spectrum the colors. Beginning from the side of the spectrum wherein the light is bending by the smallest angle, the colors space red, orange, yellow, green, blue, and violet.

As we deserve to see from the complying with diagram, the energy carried by light increases as us go indigenous red to blue throughout the clearly shows spectrum.

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Because the wavelength that electromagnetic radiation have the right to be as long as 40 m or as brief as 10-5 nm, the visible spectrum is only a small section of the total range of electromagnetic radiation.

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

vl = c

As a result, electromagnetic radiation that has a lengthy wavelength has a low frequency, and radiation through a high frequency has a brief wavelength.


Practice difficulty 4:

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