1. Atomic Number Of Elements From 1 To 300
2. Atomic Number Of Elements From 1 To 30 Chart

Click a column header, such as Name, to sort the table by that item.
SEENotes at the bottom of the Table.

Standard atomic weight is used to give the value of the mean of the atomic masses in a mixture of isotopes in a given sample of an element. Atomic Mass of First 30 Elements. Given below is a table that lists the first 30 elements based on atomic number and their corresponding atomic mass.

Notes:
• Density of elements with boiling points below 0°C is given in g/l. In a sorted list, these elements are shown before other elements that have boiling points >0°C.
• Earth crust composition average values are from a report by F. W. Clarke and H. S. Washington, 1924. Elemental composition of crustal rocks differ between different localities (see article).
• Group: There are only 18 groups in the periodic table that constitute the columns of the table. Lanthanoids and Actinoids are numbered as 101 and 102 to separate them in sorting by group.
• The elements marked with an asterisk (in the 2nd column) have no stable nuclides. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.

Abbreviations and Definitions:

Electronic Configuration of First 30 Elements with Atomic Numbers (Table) Cr and Cu act as exceptions. Their electronic configuration has half and fully filled atomic orbitals i.e. 3d54s1 and 3d104s1 respectively which are more stable than partially filled orbitals such as 3d44s2 or 3d94s2. This is a list of the 118 chemical elements which have been identified as of 2021. A chemical element, often simply called an element, is a species of atoms which all have the same number of protons in their atomic nuclei (i.e., the same atomic number, or Z). Also, knowing the atomic number of an element can give us an idea about the position of the element in the Periodic Table. Atomic number of an element never changes: for example, the atomic number of oxygen is always 8, and the atomic number of Chlorine is always 18. The atomic number is marked with the symbol Z, taken from a German word zahl.

No. - Atomic Number; M.P. - melting point; B.P. - boiling point

Atomic number: The number of protons in an atom. Each element is uniquely defined by its atomic number.

Atomic mass: The mass of an atom is primarily determined by the number of protons and neutrons in its nucleus. Atomic mass is measured in Atomic Mass Units (amu) which are scaled relative to carbon, ¹²C, that is taken as a standard element with an atomic mass of 12. This isotope of carbon has 6 protons and 6 neutrons. Thus, each proton and neutron has a mass of about 1 amu.

Isotope: Atoms of the same element with the same atomic number, but different number of neutrons. Isotope of an element is defined by the sum of the number of protons and neutrons in its nucleus. Elements have more than one isotope with varying numbers of neutrons. For example, there are two common isotopes of carbon, ¹²C and ¹³C which have 6 and 7 neutrons respectively. The abundances of different isotopes of elements vary in nature depending on the source of materials. For relative abundances of isotopes in nature see reference on Atomic Weights and Isotopic Compositions.

Atomic Number Of Elements From 1 To 300

Atomic weight: Atomic weight values represent weighted average of the masses of all naturally occurring isotopes of an element. The values shown here are based on the IUPAC Commission determinations (Pure Appl. Chem. 73:667-683, 2001). The elements marked with an asterisk have no stable nuclides. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.

Electron configuration: See next page for explanation of electron configuration of atoms.

Ionization energy (IE): The energy required to remove the outermost electron from an atom or a positive ion in its ground level. The table lists only the first IE in eV units. To convert to kJ/mol multiply by 96.4869. Reference: NIST Reference Table on Ground states and ionization energies for the neutral atoms. IE decreases going down a column of the periodic table, and increases from left to right in a row. Thus, alkali metals have the lowest IE in a period and Rare gases have the highest.

Other resources related to the Periodic Table

• Chemical Evolution of the Universe
  

Atomic Number Of Elements From 1 To 30 Chart

Here is a list of the elements sorted by atomic number.