The Atom and Electromagnetic Radiation

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Fundamental Subatomic Particles Electromagnetic Radiation
Light and also Other forms 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 one atom deserve to be figured out from a collection of basic rules.

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

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

12C 13C 14C 14N

The different isotopes of an element are determined by composing the mass variety of the atom in the upper left corner of the symbol because that the element. 12C, 13C, and also 14C room isotopes that carbon (Z = 6) and also therefore contain six protons. If the atoms room neutral, they additionally must contain six electrons. The just 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 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 around the framework of the electron in one atom has actually been acquired by studying the interaction between matter and different creates of electromagnetic radiation. Electromagnetic radiation has some the the nature of both a particle and a wave.

Particles have actually a definite mass and also they occupy space. Waves have actually no mass and also yet they bring energy as they travel with space. In addition to their ability to carry energy, tide have 4 other properties properties: speed, frequency, wavelength, and 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 2nd (s-1) or hertz (Hz).

The idealized drawing of a tide in the figure below illustrates the interpretations of amplitude and wavelength. The wavelength (l) is the smallest distance between repeating points on the wave. The amplitude of the tide is the distance in between the highest possible (or lowest) suggest on the wave and the facility of heaviness of the wave.


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

vl = s

Practice difficulty 2:

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

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Practice problem 3:

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

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See more: Convert 25 Meters Is How Many Feet Conversion, Convert 25 Meters To Feet

Light and also Other creates of Electromagnetic Radiation

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

Visible light contains the narrow band of frequencies and also wavelengths in the portion of the electro-magnetic spectrum that our eyes deserve to detect. It has radiation through wavelengths between about 400 nm (violet) and 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 irradiate is focused on a prism, the irradiate rays of different wavelengths room bent through differing quantities and the light is transformed into a spectrum the colors. Beginning from the next of the spectrum where the light is bent by the smallest angle, the colors room red, orange, yellow, green, blue, and also violet.

As we can see native the complying with diagram, the energy carried by light increases as we go indigenous red to blue across the visible spectrum.


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


The electromagnetic spectrum includes radio and also TV waves, microwaves, infrared, clearly shows light, ultraviolet, x-rays, g-rays, and also cosmic rays, as displayed in the number above. These different forms that radiation all take trip at the rate of light (c). Castle differ, however, in your frequencies and also wavelengths. The product that the frequency time the wavelength the electromagnetic radiation is constantly equal come the speed of light.

vl = c

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

Practice difficulty 4:

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