What is an isotone?

An isotone corresponds to those atoms that have different mass numbers, different atomic numbers, but have the same number of neutrons. Example:   They have in common the same number of neutrons, which is 6. Video about What is an isotone  

What is an Isobar?

An Isobar corresponds to those atoms that have the same mass number (A), but different atomic number (Z), Example: 14/7C14/7N They are different atoms, but they have equal A and different Z. Video about What is an Isobar

What are Ions?

An ion is an atom or group of atoms that acquires a positive or negative charge. It is the product of a transfer of electrons. A neutral atom can either donate or accept electrons. Depending on this, cations and anions can be formed. What is a cation? A cation is formed when a neutral atom … Read more

What is the Mass Number (A)?

The Mass Number corresponds to the total number of protons (p+) plus neutrons (n) that an atom has in its nucleus. With the following equation, it is also possible to obtain the number of neutrons (n) of an atom. To represent the atomic number (Z) and the mass number (A) of a chemical element, it … Read more

What is the Atomic Number (Z)?

The Atomic Number (Z) corresponds to the number of protons (p+) that an atom has in its nucleus. When atoms are neutral, the number of protons (p+) coincides with the number of electrons (e–). To represent the atomic number (Z) and the mass number (A) of a chemical element, it is written down: The chemical … Read more

Ernest Rutherford’s Experiment

Previous Background: Thomson’s Atomic Model Since the early 1900s, two characteristics of atoms were already known: they contain electrons and they are electrically neutral. For an atom to be neutral it must contain an equal number of positive and negative charges. Thomson proposed that an atom could be visualized as a uniform positively charged sphere, … Read more

The Discovery of Electrons

Some objects exhibit a property called electric charge, which can be positive (+) or negative (-). Positive and negative charges attract, neutralize each other, while two positive or two negative charges repel each other. All material objects are made up of charged particles. An electrically neutral object has an equal number of positively and negatively … Read more

Discovery of Positive Particles

Eugen Goldstein in 1886, using a modified cathode ray tube containing hydrogen and a cathode perforated inside, observed that apart from the cathode rays (electrons), there was a luminescence that moved away from the anode (positive pole) and towards the cathode. He called this type of rays channel rays. Goldstein assumed that this type of … Read more

James Chadwick : The Neutron

Rutherford’s model of atomic structure left an important problem unsolved. It was known that hydrogen, the simplest atom, contained only one proton, and that the helium atom contained two protons. Therefore, the ratio of the mass of a helium atom to a hydrogen atom should be 2:1. (Because electrons are much lighter than protons, their … Read more

Dalton’s Atomic Theory

In the 5th century B.C. the Greek philosopher Democritus expressed the idea that all matter was made up of many small, indivisible particles which he called atoms (meaning indestructible or indivisible). Although Democritus’ idea was not accepted by many of his contemporaries (among them Plato and Aristotle), it was maintained. Experimental evidence from some scientific … Read more