atomic number atomic weight

Let us consider the following entries in a Students' Journal: (a) Weight of a calorimeter = 42 g (measuring instrument used is spring balance) The smallest reading the spring balance can record is 1g. There are 42 of 1 g units of measurement. Hence, there are two significant figures in th..

Atomicity is the number of atoms of an element present in one molecule of that element. They can be monoatomic (He), diatomic (H 2 ), triatomic (O 3 ) and polyatomic (S 8 ..

Atoms and Molecules - Summary The law of conservation of mass states that the masses of the reactants and products remain unchanged. The law of constant proportions states that all pure specimens of a compound always contain the same elements combined together in the same proportion by ..

. In 1793, he left for Manchester to teach physics and chemistry in a college. In 1801, he observed and discovered the law of expansion of gases on heating. He also enunciated the law of partial pressures and found methods of determining vapour pressure of gases. He invented the dew point hygromete..

Atomic Number and Atomic Mass - The nuclei of atoms is made up of protons and neutrons. These two components of the nucleus are referred to as nucleons. The electrons occupy the space outside the nucleus. Since an atom is electrically neutral, the h..

The nuclei of atoms is made up of protons and neutrons. These two components of the nucleus are referred to as nucleons. The electrons occupy the space outside the nucleus. Since an atom is electrically neutral, the number of protons in the nucleus is exactly equ..

The number of protons or the number of electrons in an atom in its normal state is called the atomic number and is denoted by Z. The nucleus of every element contains Z protons and some number of neutrons. The electrons, having the same ch..

This is the number of protons present in the nucleus or the number of electrons present outside the nucleus. It is denoted by the letter Z. Atomic number (Z) = Nuclear charge or number of protons (p) = Number of electrons ..

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 scale in which the relative atomic masses of different atoms are expressed is called atomic mass unit scale. Atomic masses are not expressed as whole numbers because natural elements are mixtures of two or more isotopes. The atomic ..