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Subatomic Particles

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Atoms are the basic building bricks of chemistry. Small as atoms are they in turn consist of even smaller entities called subatomic particles. Although physicists have found several dozen of these chemist need only three - protons, neutrons and electrons. These subatomic particles differ in mass and charge.


In 1935 it was believed the internal structure of the atom had been determined. The proton, electron and neutron had been discovered and although these were considered fundamental particles still more particles were being theorized and discovered. Matter is more complex than Dalton believed. A wealth of experimental evidence obtains over the last 100 years or so has convinced us that atoms are not indivisible but rather consist of even smaller particles called subatomic particles.

What is a Subatomic Particle?

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Subatomic Particles Definition

"Subatomic particles are particles that are smaller than atoms. Historically the discovery of subatomic particles were considered to be electrons, protons and neutrons."

However the definition of subatomic particles has now been expanded to include elementary particles, which are the particles has now been expanded to include elementary particles. To define subatomic particles is the atom is the smallest part of matter that represents a particular element and no matter what the element, the same subatomic particles make up the atom. The number of the various subatomic particles is he only thing that varies.

Subatomic Particles of an Atom

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An atom is the smallest piece of a chemical element that can exist on its own. Atoms are extremely small and everything in the universe is made of them. Atoms themselves are made of even smaller pieces of matter called subatomic particles. These subatomic particles in an atom include protons, neutrons and electrons.

Scientist now recognize that there are many subatomic particles. As far chemistry is concerned we really need to be concerned only with three major subatomic particles. The examples of subatomic particles are protons, electrons and neutrons. The names of subatomic particles are given below.

  1. Protons - The subatomic particle found in the atom's dense central core that has a positive charge.
  2. Neutrons - The subatomic particle found in the atom's dense central core that has no charge.
  3. Electrons - The subatomic particle found outside the atom's dense central core that has a negative charge.


Subatomic Particles of an Atom

Subatomic Particles list

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All matter essential to life is made up of atoms consisting of protons, neutrons and electrons. The electron is a stable particle belonging to a class of subatomic particles known as fermions. The subatomic particles table is given below summarizes the list of subatomic particles characteristics.

Name
Symbol Charge
Location
Proton P+
+1
Nucleus
Neutron
n0
0
Nucleus
Electron
e-
-1
Outside nucleus

The subatomic particles chart given above describes the symbol, charge and the location of the subatomic particle in an atom.

3 Subatomic Particles

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The atom is the smallest part of matter that represents a particular element. The atoms was thought to be the smallest part of matter that could exist. But in the latter part of the 19th century and 20th century scientist discovered atoms are composed of certain subatomic particles and that no matter what the element the same subatomic particles make up the atom.

The three subatomic particles are very small and they are the building blocks of the atoms. 3 types of subatomic particles are found in an atom. Scientist now recognize that there are many subatomic particles. But the 3 main subatomic particles are
  1. Protons
  2. Neutrons
  3. Electrons

Mass of Subatomic Particles

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The subatomic particles differ in mass and charge. Like the atom the subatomic particles mass are expressed in atomic mass units.
  1. The proton p, has a mass of 1.007177u and a unit charge of +1. This charge is equal to 1.6022 $\times$ 10-19 coulombs, where a coulomb is the amount of electrical charge involved in a flow of electrical current of 1 ampere for 1 second.
  2. The neutron n has no electrical charge and a mass of 1.009665u. The proton and neutron each have a mass of essentially 1u and are said to have a mass number of 1.
  3. The electron e has an electrical charge of -1. It is very light however with a mass of only 0.00054859u about $\frac{1}{1840}$ that of the proton or neutron. Its mass number is 0.

The masses of subatomic particles are given below.

Subatomic particle
Mass (g)
Mass in amu
Proton
1.673 $\times$ 10-24 1
Neutron
1.675 $\times$ 10-24 1
Electron
9.109 $\times$ 10-23 0.0005

The masses of the subatomic particles are given in two ways grams and amu, which stands for atomic mass units. Expressing mass in amu is much easier than using the gram equivalent.

Subatomic Particles in the Nucleus

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The atom could be roughly compared to the sun with the planets rotating around it. Like the sun the atom has a central part, called the nucleus, while the outer region is composed of subatomic particles called electrons.

Protons and neutrons are found in the atoms center or nucleus. Because protons have a positive electrical charge and neutrons have no charge at all, the nucleus of an atom is always positively charged.
Although the center of the atom is the nucleus. Although only one-tenth (1/10th) the size of the atom, most of its concentrated here. The nucleus is mainly composed of two subatomic particles, the proton and the neutron.

Protons and neutrons are collectively called nucleons. Since neutrons have no charge the nucleus is positively charged.

Positively Charged Subatomic Particle

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  1. Proton is positively charged subatomic particle found in the nucleus.
  2. The total number of protons in the nucleus is given on the periodic table by the atomic number and positively identifies the element.
  3. A change in the number of protons changes the identity of the element therefore different elements must have different atomic numbers.

Negatively Charged Subatomic Particles

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  1. Electrons are negatively charged subatomic particles located around the nucleus in predictable regions called orbitals.
  2. In a neutral atom, the number of electrons is equal to the number of protons.
  3. A change in the number of electrons in a neutral atom creates an ion an electrically charged atom.
  4. Electrons do not contribute significantly to the overall mass of the atom.

Neutral Subatomic Particle

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  1. Neutrons are neutral subatomic particle also located in the nucleus.
  2. They carry no charge and therefore do not affect nuclear charge or the number of electrons in a neutral atom.
  3. Neutrons do contribute significantly to the mass of the atom because their mass is about the same as a proton.
  4. The number of neutrons contained in any nucleus is determined by subtracting the atomic number from the mass number.

Smallest Subatomic Particle

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  1. Electrons are the smallest subatomic particles.
  2. They can be found in the space surrounding the nucleus.
  3. They can be found in the space surrounding the nucleus.
  4. They orbit the nucleus in layers called shells.
  5. An atom can have between one and seven shells depending on the number of electrons orbiting the nucleus.
  6. A shell may contain a single electron or may contain dozens.

Properties of Subatomic Particles

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Experiments have shown that atoms are composed of three principle kinds of subatomic particles: protons, neutrons and electrons. Experiments also shows that at the center of an atom there exist a very tiny, extremely dense core called the nucleus, which is where an atoms protons and neutrons are found.

Protons and neutrons are much more massive than the electron, so in any atom almost all of the atomic mass is contributed by the particles that are found in the nucleus. The properties of subatomic particles are tabulated below.

Particle
Mass (g)
Electrical charge
Symbol
Proton
1.6726217 $\times$ 10-24 1+
1H1, 1P1
Neutron
1.6749273 $\times$ 10-24 0
0n1
Electron
9.109383 $\times$ 10-24
1-
-1e0

The diameter of an atom is approximately 10,000 times the diameter of its nucleus, so almost all the volume of an atom is occupied by its electrons which fill the space around the nucleus.

Characteristics of Subatomic Particles

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Mass and electrical charge are characteristics that differentiate one subatomic particle from another. A proton has one unit of positive charge and an electron one unit of negative charge. Neutrons have no charge-they are electrically neutral.

The mass of proton and neutron are nearly equal. The fundamental characteristics of three subatomic particles are tabulated below.

Characteristics of subatomic particles
Subatomic particle Symbol
Actual charge (in coulomb)
Relative charge
Actual mass (in grams)
Relative mass Mass (in atomic mass units)
Electron
e-
1.60 $\times$ 10-19 -1 9.109 $\times$ 10-28 $\frac{1}{1837}$
0
Proton
p+
1.60 $\times$ 10-19 +1
1.673 $\times$ 10-24 1 1
Neutron
n0
0
0
1.676 $\times$ 10-24
1
1