This fact has key implications for the building up of the periodic table of elements. The ordering of the electrons in the ground state of multielectron atoms, starts with the lowest energy state (ground state) and moves progressively from there up the energy scale until each of the atom’s electrons has been assigned a unique set of quantum numbers.

It is the Pauli exclusion principle that requires the electrons in an atom to occupy different energy levels instead of them all condensing in the ground state. In the periodic table, the elements are listed in order of increasing atomic number Z. The number of electrons in each element’s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. The configuration of these electrons follows from the principles of quantum mechanics. The chemical properties of the atom are determined by the number of protons, in fact, by number and arrangement of electrons. See also: Atomic Number – Does it conserve in a nuclear reaction? Atomic Number and Chemical PropertiesĮvery solid, liquid, gas, and plasma is composed of neutral or ionized atoms. It is the electrons that are responsible for the chemical bavavior of atoms, and which identify the various chemical elements. In a neutral atom there are as many electrons as protons moving about nucleus. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10 -19 coulombs. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. The nucleus is composed of protons and neutrons. The atom consist of a small but massive nucleus surrounded by a cloud of rapidly moving electrons.

K) 97 Thermal Conductivity 36 Specific Heat 0.24 Heat of Fusion 2.092 Heat of Vaporization 67.74 Atomic Number of CaesiumĬaesium is a chemical element with atomic number 55 which means there are 55 protons and 55 electrons in the atomic structure.

Caesium – Properties Element Caesium Atomic Number 55 Symbol Cs Element Category Alkali Metal Phase at STP Solid Atomic Mass 132.9055 Density at STP 1.879 Electron Configuration 6s1 Possible Oxidation States +1 Electron Affinity 45.5 Electronegativity 0.79 1st Ionization Energy 3.8939 Year of Discovery 1860 Discoverer Kirchhoff, Gustav & Bunsen, Robert Thermal properties Melting Point 28.4 Boiling Point 669 Thermal Expansion µm/(m

Caesium facts