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 variety of protons, neutrons, and also electrons in an atom deserve to be identified from a set of basic rules.

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

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


12C 13C 14C 14N

The various isotopes of an element are identified by writing the mass variety of the atom in the top left edge of the symbol for the element. 12C, 13C, and also 14C space isotopes that carbon (Z = 6) and also therefore contain 6 protons. If the atoms are neutral, they additionally must contain six electrons. The just difference between these isotopes is the variety of neutrons in the nucleus.

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

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

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


Practice problem 1:

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

Click below to check your answer come Practice trouble 1


Electromagnetic Radiation

Much that what is known around the framework of the electron in an atom has actually been acquired by studying the interaction in between matter and different develops of electromagnetic radiation. Electromagnetic radiation has actually some of the nature of both a particle and also a wave.

Particles have actually a definite mass and they accounting space. Waves have no mass and yet they lug energy as they travel with space. In enhancement to their ability to carry energy, tide have four other properties properties: speed, frequency, wavelength, and amplitude. The frequency (v) is the variety of waves (or cycles) every unit that time. The frequency the a tide is reported in devices of cycles per second (s-1) or hertz (Hz).

The idealized drawing of a tide in the figure listed below illustrates the interpretations of amplitude and also wavelength. The wavelength (l) is the the smallest distance between repeating points on the wave. The amplitude that the tide is the distance between the highest possible (or lowest) allude on the wave and also the center of gravity of the wave.

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If us measure the frequency (v) of a tide in cycles per 2nd and the wavelength (l) in meters, the product that these two numbers has actually the units of meters every second. The product the the frequency (v) times the wavelength (l) that a tide is therefore the speed (s) at which the wave travels v space.

vl = s


Practice difficulty 2:

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

Click below to inspect your answer come Practice difficulty 2


Practice problem 3:

Orchestras in the United states 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 the this note?

Click below to inspect your answer come Practice difficulty 3

Click here to watch a solution to Practice problem 3




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Light and also Other develops of Electromagnetic Radiation

Light is a wave through both electric and also magnetic components. That is as such a kind of electromagnetic radiation.

Visible light contains the narrow band of frequencies and also wavelengths in the section of the electro-magnetic spectrum the our eyes can detect. It contains radiation through wavelengths between about 400 nm (violet) and 700 nm (red). Due to the fact that it is a wave, irradiate is bent once it beginning a glass prism. When white light is focused on a prism, the irradiate rays of various wavelengths are bent by differing amounts and the irradiate is transformed into a spectrum that colors. Beginning from the side of the spectrum whereby the light is bent by the smallest angle, the colors space red, orange, yellow, green, blue, and violet.

As we can see from the adhering to diagram, the energy carried by light increases as us go from red to blue throughout the clearly shows spectrum.

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Because the wavelength the electromagnetic radiation can be as long as 40 m or as quick as 10-5 nm, the clearly shows spectrum is just a small portion of the total range of electromagnetic radiation.

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

vl = c

As a result, electromagnetic radiation that has actually a long wavelength has a low frequency, and also radiation v a high frequency has actually a brief wavelength.


Practice difficulty 4:

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