You isotopes, isobars and isotones are classifications of atoms of chemical elements present in the periodic table, according to the amount of protons, electrons and neutrons present in each one of them.
Thus, isotopes are elements that have the same number of protons, isobars have the same number of mass, while isotopes have the same number of neutrons.
It is important to note that the protons (p) have a positive charge, the electrons (e), negative charge and the neutrons (n), do not have charge (neutrality) and according to the structure of atoms, protons and neutrons are concentrated in the nucleus, while electrons are located in the electrosphere, that is, around the core.
Chemical element
Each chemical element of periodic table is represented by a symbol, for example the H (hydrogen), where at the top the mass number (A) is indicated, while the atomic number (Z) is located at the bottom of the symbol, for example: zHTHE
Atomic Number (Z)
O atomic number (Z) represents the amount of protons present in each atom.
Thus, the number of protons is equal to the number of electrons (p = and), since the atom corresponds to an electrically neutral particle, that is, with the same number of opposite charges: positively charged protons and negatively charged electrons.
Mass Number (A)
O mass number (A) of each atom, corresponds to the sum of protons and neutrons (A=p+n) present in the element's core.
It is important to note that the electron, as it has an insignificant mass, that is, 1836 times smaller in relation to protons and neutrons, are not included in the sum of the masses of chemical elements. For this reason, the mass number does not match the actual or actual mass of the atom.
isotopes
Isotopes (isotopy) are atoms of the same chemical element which have the same atomic number (Z) and different mass numbers (A).
Isobars
Isobars (isobaria) are atoms of different chemical elements which have the same mass number (A) and different atomic numbers (Z).
Isotones
Isotones (isotony) are atoms of different chemical elements which have different atomic numbers (Z), different mass numbers (A) and the same number of neutrons.
Exercises
- According to the representation of the chemical elements below, calcium (Ca), potassium (K) and argon (Ar) can we classify them as isotopes, isotones or isobars?
20Here40, 19K40, 18Air40
If in the representation of the chemical element, the mass number corresponds to the sum of protons and neutrons (A= p + n) in the above representation, note that the numbers appearing at the top of the letter are equal: 40.
Thus, it is concluded that calcium, potassium and argon are elements isobars since they have the same mass number (A) and different atomic numbers (Z), these, represented by the numbers located at the bottom of the element (20, 19, 18).
- According to the classification of chemical elements (isotopes, isobars and isotones), group the atoms shown:
90THE232, 91B234, 90Ç233, 92D233, 93AND234.
Note that all of the above elements have the mass number and the atomic number, however they don't have the neutron number. Thus, to group them according to chemical classification (isotopes, isobars and isotones), the number of neutrons present in each element must be calculated using the formula (A=p+n):
Element A: 90THE232
A = p + n
232 = 90 + n
232 - 90 = n
142 = n
Element B: 91B234
A = p + n
234 = 91 + n
234 - 91 = n
143 = n
Element C: 90Ç233
A = p + n
233 = 90 + n
143 = n
Element D: 92D233
A = p + n
233 = 92 + n
141 = n
Element E: 93AND234
A = p + n
234 = 93 + n
141 = n
Soon,
- The elements 90THE232 and 90Ç233 they are isotopes for they have the same atomic number and different mass numbers;
- The elements (91B234 and 93AND234) and (90Ç233 and 92D233) they are isobars since they have the same mass number and different atomic numbers;
- The elements (91B234 and 90Ç233) and (92D233 and 93AND234) they are isotones because they have the same number of neutrons and different mass numbers and atomic numbers.
read Atomic Mass.
