The Atom and also Electromagnetic Radiation

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Fundapsychological Subatomic Particles Electromagnetic Radiation
Light and Other Forms of Electromagnetic Radiation

Pwrite-up 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 electrons in an atom have the right to be identified from a set of straightforward rules.

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

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

12C 13C 14C 14N

The different isotopes of an element are established by composing the mass number of the atom in the top left edge of the symbol for the aspect. 12C, 13C, and also 14C are isotopes of carbon (Z = 6) and therefore contain six proloads. If the atoms are neutral, they additionally must contain 6 electrons. The only distinction between these isotopes is the number of neutrons in the nucleus.

12C: 6 electrons, 6 proloads, and 6 neutrons

13C: 6 electrons, 6 prolots, and also 7 neutrons

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

Practice Problem 1:

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

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Electromagnetic Radiation

Much of what is recognized around the framework of the electrons in an atom has actually been acquired by studying the interactivity between matter and also different develops of electromagnetic radiation. Electromagnetic radiation has some of the properties of both a particle and also a wave.

Particles have actually a definite mass and also they occupy area. Waves have no mass and also yet they carry energy as they take a trip through area. In addition to their ability to bring power, waves have four other characteristic properties: rate, frequency, wavelength, and also amplitude. The frequency (v) is the variety of waves (or cycles) per unit of time. The frequency of a wave is reported in units of cycles per second (s-1) or hertz (Hz).

The idealized illustration of a wave in the figure listed below illustrates the meanings of amplitude and also wavesize. The wavelength (l) is the smallest distance in between repeating points on the wave. The amplitude of the wave is the distance between the greatest (or lowest) allude on the wave and also the center of gravity of the wave.


If we measure the frequency (v) of a wave in cycles per second and also the wavesize (l) in meters, the product of these 2 numbers has the systems of meters per second. The product of the frequency (v) times the wavesize (l) of a wave is therefore the speed (s) at which the wave travels via area.

vl = s

Practice Problem 2:

What is the speed of a wave that has actually a wavesize of 1 meter and also a frequency of 60 cycles per second?

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Practice Problem 3:

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

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Light and Other Forms of Electromagnetic Radiation

Light is a wave via both electrical and also magnetic components. It is therefore a kind of electromagnetic radiation.

Visible light has the narrow band of frequencies and also wavelengths in the percentage of the electro-magnetic spectrum that our eyes can detect. It consists of radiation via wavelengths in between about 400 nm (violet) and also 700 nm (red). Since it is a wave, light is bent as soon as it enters a glass prism. When white light is focused on a prism, the light rays of various wavelengths are bent by differing quantities and the light is transdeveloped right into a spectrum of colors. Starting from the side of the spectrum wbelow the light is bent by the smallest angle, the colors are red, oselection, yellow, green, blue, and also violet.

As we can check out from the complying with diagram, the power carried by light increases as we go from red to blue across the visible spectrum.


Because the wavelength of electromagnetic radiation deserve to be as long as 40 m or as brief as 10-5 nm, the visible spectrum is just a small percentage of the full variety of electromagnetic radiation.


The electromagnetic spectrum includes radio and also TV waves, microwaves, infrared, visible light, ultraviolet, x-rays, g-rays, and cosmic rays, as displayed in the number over. These various forms of radiation all travel at the speed of light (c). They differ, yet, in their frequencies and wavelengths. The product of the frequency times the wavelength of electromagnetic radiation is always equal to the speed of light.

vl = c

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

Practice Problem 4:

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