Mass Number Of Chlorine

Mass Numbers - How to find Mass Numbers
The mass number is established by rounding the atomic weight to the nearest whole number. The Periodic Table with Atomic Masswill give you the atomic weight, or atomic mass, of the elements. The chemical properties of an element are determined by its Atomic Number not its Mass Number which is why atomic numbers are shown on the Periodic table whilst Mass Numbers are not. Mass numbers equal the total number of heavy, or massive, particles in the nucleus. Subtracting the Atomic number from the Mass Number equals the number of neutrons in the nucleus.

Chlorine Atomic Number And Mass

The molar mass of one chlorine atom is 35.45g/mol, as can be found in the Periodic Table of Elements. To determine the molar mass of one chlorine molecule, simply add the molar masses of the two chlorine elements, or multiply the atomic mass by two. Thus, 35.45g/mol x 2 is equal to 70.90g/mol and is the molar mass of chlorine gas.

• The atomic number of chlorine is 17 (it has 17 protons in its nucleus). To calculate the average mass, first convert the percentages into fractions (divide them by 100). Then, calculate the mass numbers. The chlorine isotope with 18 neutrons has an abundance of 0.7577 and a mass number of 35 amu.
• (a) Chlorine atom (Cl) has atomic number 17. It contains 17 protons and 17 electrons. Chlorine ion (Cl-) is formed when Cl gains one electron. So, Cl-has 18 electrons and 17 protons. Therefore, the electronic configuration of Cl-= 2, 8, 8. (b) Atomic number of Cl-= Number of protons = 17 Mass number of Cl-will be the same as Cl i.e.
• For example, the atomic mass of chlorine (Cl) is 35.45 amu because chlorine is composed of several isotopes, some (the majority) with an atomic mass of 35 amu (17 protons and 18 neutrons) and some with an atomic mass of 37 amu (17 protons and 20 neutrons).  Mass Numbers = Atomic Weight of Element, rounded to nearest whole number Number of Neutrons = Mass Number - Atomic Number Mass Numbers

Mass Numbers - The Mass Numbers of all of the elements
So, if we know the number of protons and neutrons in an atom we can determine the mass number. The unique chart below has been created by www.elementalmatter.info and details all of the elements in the Periodic table, the numbers of protons, the numbers of neutrons and the mass numbers of atoms which relate to the elements.

Mass numbers - Examples of Mass Numbers
The following examples provide details of how to calculate the mass number.

• Example 1 - mass number of Gold: The element Gold (Symbol Au) has the Atomic Number of 79. The number of protons in atom of gold is therefore 79. Gold has the Atomic Mass weight of 196.97. Round to the nearest whole number. The mass number of gold is therefore 197.
• Example 2 - mass number of Silver: The element Silver (Symbol Ag) has the Atomic Number of 47. The number of protons in atom of silver is therefore 47. Silver has the Atomic Mass weight of 107.87. Round to the nearest whole number. The mass number of silver is therefore 108.
• Example 3 - mass number of Neon: The element Neon (Symbol Ne) has the Atomic Number of 10. The number of protons in atom of neon is therefore 10. Neon has the Atomic Mass weight of 20.18. Round to the nearest whole number. The mass number of neon is therefore 20.

Mass Number Of Chlorine Rounded Mass Numbers = Atomic Weight of Element, rounded to nearest whole number

Mass numbers - Chart of Mass Numbers
The details all of the elements in the Periodic table, the numbers of protons, the numbers of neutrons and the mass numbers of atoms which relate to the elements in the Periodic Table.