Definition of Proton
Proton is a stable subatomic particle with a positive charge equal in magnitude to a unit of electron charge and a rest mass of 1.67262 × 10-27 kg, which is 1,836 times the mass of an electron.
- Every nucleus of a given chemical element has the same number of protons. This number defines the atomic number of an element and determines the element’s position in the periodic table. When the number of protons in a nucleus equals the number of electrons orbiting the nucleus, the atom is electrically neutral.
- Protons are a type of subatomic particle with a positive charge. Protons are bound together in an atom’s nucleus as a result of the strong nuclear force.
- The positive charge on a proton is equal in magnitude to the negative charge on an electron. As a result, a neutral atom must have an equal number of protons and electron.
Mass of Proton
The proton’s mass is 1.6726219 × 10-27 kilograms. Protons are positively charged particles, electrons are negatively charged, and neutrons have no charge. In an atom, the number of protons and electrons are equal. Thus an atom is electrically neutral in nature.
Charge on Proton
Protons have a charge of +1 and a mass of 1 atomic mass unit, which is approximately equal to 1.66×10-24 grams. The number of protons in an atom defines the element’s identity (an atom with 1 proton is hydrogen, for example, and an atom with two protons is helium).
Discovery of Proton
The discovery of the proton is credited to Ernest Rutherford. In his famous gold foil experiment, he proved that the nucleus of the hydrogen atom (i.e., a proton) is present in the nuclei of all other atoms in the year 1917.
He concluded that all the positively charged particles in an atom were concentrated in a singular core and that most of the atom’s volume was empty.
He also stated that the total number of positively charged particles in the nucleus equals the total number of negatively charged electrons present around it.
How the Proton was Discovered?
Proton was discovered by the gold foil experiment;
- Ernest Rutherford observed that his scintillation detectors detected hydrogen nuclei when a beam of alpha particles was shot into the air.
- After investigating further, Rutherford found that these hydrogen nuclei were produced from the nitrogen atoms present in the atmosphere.
- He then proceeded to fire beams of alpha particles into pure nitrogen gas and observed that a greater number of hydrogen nuclei were produced.
- He concluded that the hydrogen nuclei originated from the nitrogen atom, proving that the hydrogen nucleus was a part of all other atoms.
- This experiment was the first to report a nuclear reaction, given by the equation: 14N + α → 17O + p [Where α is an alpha particle which contains two protons and two neutrons, and ‘p’ is a proton].
- The hydrogen nucleus was later named ‘proton’ and recognized as one of the building blocks of the atomic nucleus.
Properties of Proton
These are some properties of proton
1. Physical Properties
Protons have slightly less mass than the neutrons in the nucleus, but they are 1,836 times more massive than electrons. The actual mass of the proton is 1.6726 x 10^-27 kilograms, which is a very small mass indeed.
The symbol “^-” represents a negative exponent. This number is a decimal point followed by 26 zeros, then the number 16726. In terms of electrical charge, the proton is positive.
2. Function in the Atom
The protons inside an atom’s nucleus help bind the nucleus together. They also attract the negatively charged electrons and keep them in orbit around the nucleus.
The number of protons in an atom’s nucleus determines which chemical element it is. That number is known as the atomic number; it is frequently denoted with a capital “Z.”
3. Experimental Use
In large particle accelerators, physicists accelerate protons to very high speeds and force them to collide. This creates cascades of other particles.
4. Energy for Stars
Inside the sun and all other stars, protons combine with other protons by means of nuclear fusion. This fusion requires a temperature of approximately 1 million degrees Celsius.
This high temperature causes two lighter particles to fuse into a third particle. The mass of the created particle is less than that of the two initial particles combined.
Stability of Protons
The free proton (a proton not bound to nucleons or electrons) is a stable particle that has not been observed to break down spontaneously to other particles.
The free protons are found naturally in a number of situations in which energies or temperatures are high enough to separate them from electrons, for which they have some affinity.
Free protons exist in plasmas in which temperatures are too high to allow them to combine with electrons. Free protons of high energy and velocity make up 90% of cosmic rays, propagating in a vacuum for interstellar distances.
The free protons are emitted directly from atomic nuclei in some rare types of radioactive decay. Protons also result (along with electrons and antineutrinos) from the radioactive decay of free neutrons, which are unstable.
Proton in Chemistry
Free protons occasionally occur on Earth: thunderstorms can produce protons with energies of up to several tens of MeV. At sufficiently low temperatures and kinetic energies, free protons will bind to electrons.
However, the character of such bound protons does not change, and they remain protons. A fast proton moving through matter will slow by interactions with electrons and nuclei until the electron cloud of an atom captures it.
The result is a protonated atom, which is a chemical compound of hydrogen. When free electrons are present in a vacuum, a sufficiently slow proton may pick up a single free electron, becoming a neutral hydrogen atom, which is chemically a free radical.
Such “free hydrogen atoms” tend to react chemically with many other types of atoms at sufficiently low energies. When free hydrogen atoms react, they form neutral hydrogen molecules (H2), which are the most common molecular component of molecular clouds in interstellar space.
In chemistry, the term proton refers to the hydrogen ion, H+. Since the atomic number of hydrogen is 1, a hydrogen ion has no electrons.
It corresponds to a bare nucleus, consisting of a proton (and 0 neutrons for the most abundant isotope protium 1 H). The proton is a “bare charge” with only about 1/64,000 of the radius of a hydrogen atom and so is highly reactive chemically.
The free proton, thus, has an extremely short lifetime in chemical systems such as liquids, and it reacts immediately with the electron cloud of any available molecule.