The Atom and also Electromagnetic Radiation

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Fundamental Subatomic Particles Electromagnetic Radiation
Light and also 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 determined from a set of straightforward rules.

The number of protons in the nucleus of the atom is equal to the atomic number (Z). The variety 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 variety of protons and also 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 recognize the number of protons, neutrons, and also electrons in the following isotopes.

12C 13C 14C 14N

The various isotopes that an facet are figured out by creating the mass number of the atom in the top left edge of the symbol because that the element. 12C, 13C, and also 14C space isotopes of carbon (Z = 6) and therefore contain six protons. If the atoms are neutral, they also must contain six electrons. The just difference in between these isotope is the number 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 8 neutrons

Practice problem 1:

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

Click below to examine your answer come Practice trouble 1

Electromagnetic Radiation

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

Particles have actually a identify mass and also they occupy space. Waves have no mass and yet they lug energy together they travel through space. In enhancement to their capacity to bring energy, tide have 4 other characteristics properties: speed, frequency, wavelength, and amplitude. The frequency (v) is the variety of waves (or cycles) per unit the time. The frequency that a tide is reported in devices of cycles per 2nd (s-1) or hertz (Hz).

The idealized drawing of a wave in the figure listed below illustrates the definitions of amplitude and wavelength. The wavelength (l) is the smallest distance in between repeating points on the wave. The amplitude the the wave is the distance in between the highest (or lowest) suggest on the wave and also the center of heaviness of the wave.


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

vl = s

Practice trouble 2:

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

Click here to inspect your answer come Practice difficulty 2

Practice problem 3:

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

Click right here to inspect your answer come Practice problem 3

Click below to check out a equipment to Practice problem 3

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Light and also Other develops of Electromagnetic Radiation

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

Visible light contains the narrow band the frequencies and wavelengths in the part of the electro-magnetic spectrum that our eyes have the right to detect. It has radiation with wavelengths between around 400 nm (violet) and 700 nm (red). Due to the fact that it is a wave, irradiate is bent as soon as it enters a glass prism. Once white irradiate is focused on a prism, the light rays of different wavelengths are bent through differing quantities and the irradiate is transformed right into a spectrum of colors. Starting from the next of the spectrum whereby the light is bent by the the smallest angle, the colors are red, orange, yellow, green, blue, and also violet.

As we can see indigenous the adhering to diagram, the energy brought by light increases as we go native red to blue throughout 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 only a small section of the total variety of electromagnetic radiation.


The electromagnetic spectrum has radio and also TV waves, microwaves, infrared, visible light, ultraviolet, x-rays, g-rays, and cosmic rays, as presented in the figure above. These different forms the radiation all take trip at the speed of irradiate (c). Castle differ, however, in their frequencies and also wavelengths. The product the the frequency times the wavelength the electromagnetic radiation is constantly equal to the rate of light.

vl = c

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

Practice problem 4:

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