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nofret eNotes educator| Certified Educator

An atom has 3 basic particles that it is composed of.  They are protons, neutrons, and electrons.  The protons are located in the nucleus of the atom and have an atomic mass of about 1 amu (atomic mass unit).  They are positively charged.  How many protons an atom has is called the atomic # of the atom and atoms on the periodic table are arranged according to their atomic #s.  Calcium, for example, has an atomic # of 20, meaning that it has 20 protons. 

     Neutrons are the other atomic particle that are found in the nucleus of the atom.  They are also about 1 amu, but they do not have a charge.  Together the number of protons + the number of neutrons = the atomic mass of the element.  Calcium has an atomic mass of 40.  So to figure out how many neutrons there are:

  Protons + Neutrons = atomic mass

     20     + Neutrons = 40

so subtract: 40-20= 20 Calcium has 20 neutrons.  

The number of neutrons will not always equal the number of protons.   

      The last atomic particle is the electron.  The electrons are very small compared to the protons and neutrons (1/1840 amu) and are negatively charged.  They orbit around the nucleus.  In a neutral atom, the number of electrons will always be equal to the number of protons.  So, calcium has an atomic # of 20, which means it has 20 protons and 20 electrons. 

These are the 3 basic particles that make up an atom.

neela | Student

Atoms are the smallest basic unit of the elements. Thre are about 90 elements. So there are 90 diffrent types of atoms. A molecule is a cluster of atoms of single element or diffrent atoms in a compound. The parts of the atoms are according to models of the atoms what they consist of. An atom consists of subatomic particles like nutron and proton at the centre and the electrons at various shells  orbitting around the centre or nuleus. Protons and elecrons are equal inumber. The proton  has a positve charge and the electron has a negative charge but equal in magnitude to that of proton.The nutron particle is nutral or has no charge.

Nutron is not present in the atom of normally occuring hydrogen.

The atomic number is the number that indicates the number of protons (or electrons) of an element. The atomic mass is on account of the mass of proton and nutron of an atom. The mass of nutron , proton and electrons are  1.67493*10^-(27) 1.67262*10^(-27) kg and  9.10939*10^(-31) kg. The mass of the electron is negligible compared to that of nutron anor proton. The nutron is slightly more mass than that of proton.

The electrons are orbitting around the nucleus in different shells and each shell consits of not more than 2n^2 electrons, where n is the quantum number of the shell and the outer most shell or valence shell could have maximum of 8 electrons.





giorgiana1976 | Student

A series of experiences made in the nineteenth century and early twentieth century, which led to the discovery of the electron, the cathode rays, the
X-rays, radioactivity showed that the atom, contrary to the name significance (atoms in Greek means indivisible), can not be considered  as a unitary particle, but as a complex system made up of other  masses less parts, some charged, others neutral.In 1904, J.J. Thomson proposed the first model of the atom: he conceives atom as a positively charged sphere, inside which electrons are distributed in symmetrical fashion. The static model of the atom was available by that 
time, being replaced later by that of Rutherford, as it
could explain many of the properties of the atom.

Rutherford proposed the nuclear model of the atom in 1912, saying that in center atom is a very small core-loaded with positive electricity,where almost the entire mass of the atom is concentrated  and around which rotate on circular orbits at certain distances, negative charged particles electrons, like planets revolving around the Sun. After conceptualisations
Rutherford knew, most of the atomic volume is empty,electrons  are animated by a continuous circular motion on orbit and they are maintained in balance due to centrifugal force balanced by the force of attraction between the positive nucleus and negative electrons. According to Rutherford's model, the atom of any element consists of two distinct parts:
-a central system called the kernel,
-outside of kernel, a part called the electronic shell

Atomic nucleus, although it is around the 10,000th of the atom diameter , contains almost the entire mass of the atom. It consists of several kinds of elementary particles from which,for the chemistry problems that we're
interested, we'll retain only:
- Protons - material particles  loaded with one electric elementary positive charge and whose mass is equal approximately to unity atomic mass (1.00727 0.000003 u.a.m.) and
- Neutron - neutral material particles, which also have the mass roughly equal  with atomic mass unit (1.00866).
For protons and neutrons, as part of the kernel, is used today the name nucleons, name justified by possible nuclear transformations: neutron =proton + electron, which means that the two particles would have two different quantum states of the same particles - nucleons.

krishna-agrawala | Student

Atom is the smallest possible particle of an element. Atoms combine to form molecules, that are the smallest possible particle in a stable state of any element or compound. All the matter in the world is thus made up of atoms of about 90 elements.

The atom itself consists of a nucleus surrounded by electrons that circle around it. The nucleus itself is composed of two different type of particles, protons and neutrons.

proton has one unit positive charge while electron has one unit negative charge. The number of electrons and protons in an atom is same. Neutrons have no charge. Thus the net electric charge in an atom is zero.

neutron and protons, themselves consist of smaller particles called quarks. Each proton and electron consists of three quarks.

atyourservice | Student

The parts of an atom are the protons which are positively charged, neutrons which are neither positive nor negative and electrons which are negatively charged.

The protons and neutrons make up the nucleus and the electrons surround the nucleus.

An atom is made up of three parts: 

proton: positively charged particles

neutron: neutrally charged particles

Electron: negatively charged particles.

The atom has a center, or nucleus made up of proton and neutrons which are significantly larger then electrons, which are hovering around the nucleus.

Jyotsana | Student

The three parts of an atom are protons, neutron  and Electron. Protons have a positive charge, electrons have a negative charge, and neutrons have no charge.

kshitijthe123420 | Student
There are three parts of an atom: protons, neutron, and electrons. Protons have a positive charge, electrons have a negative charge, and neutrons possess no net charge. Electrons are the smallest parts of the atom. They are the most numerous of the three. It has no known components or substructure, so it is an elementary particle. Its mass is 1/1836 of a proton. It is also considered to be a fermion. It has an antiparticle called the positron. The positron is identical to the electron except that it carries opposite charge. When an electron collides with a positron, both particles will either scatter or be destroyed producing gamma ray photons. Electrons can collide with other particles and be diffracted like light. Two electrons can not occupy the same quantum state based on the Pauli exclusion principle. The proton is the part of an atom that helps to form the nucleus and has a positive charge. Protons must have an equal number of neutrons except int eh hydrogen atom where a single proton exists on its own. A proton is composed of 2 up quarks and one down quark. They are considered to be fermions and baryons. They are held together by the strong nuclear force. The number of protons in the nucleus of an atom determines the atomic number. A neutron is the part of an atom that holds no charge. Neutrons and protons occur in equal numbers in stable atoms except in hydrogen. Protons and neutrons are often referred to together as nucleons. If there are more neutrons than protons, then the atom is considered an isotope. If an neutron becomes free of its proton, then it becomes unstable, undergoes beta decay, and will disintegrate in an average of 15 minutes. The neutron is also important in nuclear chain reactions: both natural and artificial.