The shorthand notation for an atom or ion is represented by the picture above. It is commonly seen on periodic table depicting the different elements. However, even though this is shorthand to writing elements, it still relay much information to the viewer.
1) The letter(s) at the centre of the notation represents the element that it is replacing. The full element name is usually beneath this symbol.
2) The Atomic Number: This number is present at the bottom left corner of the notation. This represents multiple things:
a. The position it is on the periodic table
b. The number of protons in the atom
c. The number of electrons in the atom in its ground state.
3) The Atomic Mass: This number is present at the top left corner of the notation. This represents the total number of protons and neutrons in the nucleus of the atom. However this number may vary for the same element due to different isotopes (different number of neutrons). The atomic mass on the periodic table is showing the most common isotope of the element.
4) The Charge: This number and sign is present at the top right corner of the notation. This can help determine the number of electrons in the atom.
a. If there is no number or sign, this means the atom is in its ground state. The number of electrons equals the number of protons (look at the atomic number).
b. If there is a positive number, this means there are more electrons than protons. This atom has attracted extra number of electrons and became a cation, or positively charged ion. The number represents how many electrons were gained.
c. If there is a negative number, this means there are fewer electrons than protons. This atom has lost electrons and became an anion, or negatively charged ion. The number represents how many electrons were lost.
Let’s use carbon as an example:
Carbon has the atomic mass of 12, atomic number of 6, and no charge. This suggests that the carbon atom in question has 6 protons, 6 neutrons, and 6 electrons.
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This article was written for you by Samuel, one of the tutors with SchoolTutoring Academy.