number of protons

Atoms are made up of three fundamental particles: electrons, protons and neutrons. Discharge tube experiments by William Crookes and J.J. Thomson led to the discovery of electron. Goldstein's experiment with the discharge tube having a perforated cathode led to the discovery of an..

The distance from the centre of the nucleus to the outermost shell of an atom is called the atomic radius of that atom. Electrons in the same period progressively increase from left to right, as the atomic number increases, e.g., in the 3 rd period, from sodium (Z = 11) to chlorine ..

Atomic Size and Atomic Radius - The distance from the centre of the nucleus to the outermost shell of an atom is called the atomic radius of that atom (Fig. 2.1..

The atom of an element consists of a small, positively charged nucleus in the centre, which carries almost the entire mass of the atom. The electrons are revolving around the nucleus at high speed. The number of electrons in an atom is equal to the number of protons..

Modern Periodic Table-Long Form Periodic Table of Elements - Later, Henry Gywn-Jeffreys Moseley showed that the atomic number of an element is numerically equal to the number of electrons round the nucleus. The number of electrons in turn is equal to the number..

Isotopes - These are the elements having same atomic number but different mass number. They have the same atomic number because the number of protons inside their nuclei remains the same. The difference in their mass number is due to the d..

Atoms of the same element having the same atomic number but different mass numbers are called isotopes. The nuclei of these atoms have same number of protons but different number of neutrons. All the properties of the isotopes depending upon m..

Moseley's Law - Moseley had done experiments on the characteristic X-rays and this led to the development of the concept of atomic number. The periodic table was made according to the atomic weight in earlier days. But some anomalies were found in such an arrangement. Moseley measured the..

Photophosphorylation (Cyclic and Non-cyclic) - Photosynthetic phosphorylation or photophosphorylation is the process of phosphate group transfer into ADP to synthesize energy rich ATP molecule making use of light as external energy source. According to chemi osmotic hypothesis (Mitchell 1961) the A..

Protons and neutrons Nuclear forces Electromagnetic repulsion between the protons Nuclear fusion and fission reactions Radioactive isotopes Three most common forms of radioactive decay (alpha, beta, gamma) Changes in the nucleus in each type of decay Alpha, beta, an..