As we are aware that every matter is composed of small particles called atoms. Atoms are the fundamental components of Chemistry that are widely distributed in all states of matter namely solid, liquid and gas. Atoms may be positively (+) charged, negatively (-) charged and sometimes neutrally charged too. Let us try understanding the composition of the atom by knowing its Atomic Structure.
Know The Constituents Of An Atom
The nucleus of the atom is divided into two parts protons and neutrons. The atom is divided into three parts:
Protons: Protons are positively (+) charged particles seen inside the nucleus of the atom. It has the capacity to move freely inside an atom. The number of protons in an atom determines the atomic number of the element. Proton is approximately 1.672 * 10-24.
Neutron: The mass of a neutron weighs 1.674 * 10-24 and is the same as that of a proton. Neutrons electrically contain no charge and hence are neutral. Different elements have a different number of neutrons present in their respective nuclei.
Electrons: The electron carries -1e charge and is approximately equal to -1.602 X 10-19. Electron weighs 9.1X10-31. Since it has comparatively negligible mass, electrons are ignored when calculating the mass of an atom.
Usually, the atomic number of the element is found by
Atomic Weight = number of protons + number of neutrons
The atomic structure of an atom is as shown in the figure below. It explains the composition of the nucleus of an atom with protons and neutrons. Electrons are seen outside the nucleus.
Another important concept in the atomic structure is knowing about the Coordination Number.
It is also called as ligancy and was defined in the year 1893 by Alfred Werner,
Coordination Number refers to the total number of atoms, ion, or molecules bonded to the atom. Ligands determine the number of ions, atoms, or molecules that a central atom or ion holds.
For the polyatomic ions and molecules irrespective of the nature of the bond, the coordination number is calculated by considering the total number of atoms it is bonded to.
Example: For [Cr(NH3)2Cl2Br2]– the polyatomic ion, the coordination number of the central cation (Cr3+) can be counted by considering the total number of atoms bonded to the chromium atom that is equal to 6. The structural representation is as given below.
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