Since the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density (N atoms/cm 3), Density – Atomic Mass and Atomic Number Density The Standard English unit is pounds mass per cubic foot ( lbm/ft 3). The standard SI unit is kilograms per cubic meter ( kg/m 3). In words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. It is an intensive property, which is mathematically defined as mass divided by volume: Typical densities of various substances are at atmospheric pressure.ĭensity is defined as the mass per unit volume. 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) 23.1 Thermal Conductivity 237 Specific Heat 0.9 Heat of Fusion 10.79 Heat of Vaporization 293.4 Atomic Number of AluminiumĪluminium is a chemical element with atomic number 13 which means there are 13 protons and 13 electrons in the atomic structure.Aluminium – Properties Element Aluminium Atomic Number 13 Symbol Al Element Category Poor Metal Phase at STP Solid Atomic Mass 26.9815 Density at STP 2.7 Electron Configuration 3s2 3p1 Possible Oxidation States -2 -1 +1 +2 +3 Electron Affinity 42.5 Electronegativity 1.61 1st Ionization Energy 5.9858 Year of Discovery 1825 Discoverer Oersted, Hans Christian Thermal properties Melting Point 660 Boiling Point 2467 Thermal Expansion µm/(m

Aluminum atomic number