The Atom and also Electromagnetic Radiation

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Fundamental Subatomic Particles Electromagnetic Radiation
Light and Other develops 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 can be identified from a set of simple rules.

The number of protons in the cell nucleus of the atom is equal to the atomic number (Z). The variety of electrons in a neutral atom is same to the variety of protons. The mass number of the atom (M) is equal to the amount of the number of protons and also neutrons in the nucleus. The variety of neutrons is equal to the difference in between the mass number of the atom (M) and also 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 that an facet are determined by creating the mass variety of the atom in the upper left corner of the symbol for the element. 12C, 13C, and also 14C room isotopes the carbon (Z = 6) and therefore contain six protons. If the atoms room neutral, they also must contain six electrons. The just difference between these isotope is the number of neutrons in the nucleus.

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

13C: 6 electrons, 6 protons, and also 7 neutron

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

Practice problem 1:

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

Click right here to check your answer come Practice difficulty 1

Electromagnetic Radiation

Much the what is known about the framework of the electrons in an atom has actually been acquired by researching the interaction between matter and also different creates of electromagnetic radiation. Electromagnetic radiation has actually some of the properties of both a particle and also a wave.

Particles have actually a identify mass and they occupy space. Waves have actually no mass and yet they lug energy together they travel v space. In enhancement to their ability to lug energy, waves have four other characteristics properties: speed, frequency, wavelength, and also amplitude. The frequency (v) is the variety of waves (or cycles) every unit of time. The frequency that a tide is report in systems of cycles per second (s-1) or hertz (Hz).

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


If us measure the frequency (v) of a wave in cycles per second and the wavelength (l) in meters, the product of these two numbers has actually the units of meters every second. The product of the frequency (v) time the wavelength (l) of a wave is as such the rate (s) at which the wave travels through space.

vl = s

Practice problem 2:

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

Click below to check your answer come Practice trouble 2

Practice trouble 3:

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

Click here to check your answer to Practice difficulty 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 because of this a kind of electromagnetic radiation.

Visible light includes the narrow band that frequencies and wavelengths in the part of the electro-magnetic spectrum the our eyes deserve to detect. It consists of radiation through wavelengths between around 400 nm (violet) and also 700 nm (red). Due to the fact that it is a wave, light is bent as soon as it beginning a glass prism. Once white light is concentrated on a prism, the irradiate rays of various wavelengths space bent by differing quantities and the light is transformed into a spectrum of colors. Starting from the next of the spectrum where the light is bending by the the smallest angle, the colors space red, orange, yellow, green, blue, and also violet.

As we have the right to see from the adhering to diagram, the energy lugged by light increases as we go from red come blue across the visible spectrum.


Because the wavelength that electromagnetic radiation deserve to be as long as 40 m or as short as 10-5 nm, the visible spectrum is just a small part of the total selection of electromagnetic radiation.


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

vl = c

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

Practice trouble 4:

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