Electron configurations are a list of the subshells on an atom that are occupied.
The maximum number of electrons per subshell (s subshell - 2, p subshell - 6, d subshell - 10) equals the number of groups in these blocks in the periodic table. Thus the periodic table can be used as a guide for constructing the electron configuration of an element.
To deduce the electron configuration using the periodic table as a guide, one proceeds across the rows from left to right adding electrons to the corresponding subshells until you reach the symbol for the element.
Each subshell has a shell number and a letter designation (1s for example).
The number of electrons is given by a superscript. For H the electron configuration is 1s1.
The number of electrons is given by a superscript. For H the electron configuration is 1s1.
The maximum number of electrons per subshell (s subshell - 2, p subshell - 6, d subshell - 10) equals the number of groups in these blocks in the periodic table. Thus the periodic table can be used as a guide for constructing the electron configuration of an element.
To deduce the electron configuration using the periodic table as a guide, one proceeds across the rows from left to right adding electrons to the corresponding subshells until you reach the symbol for the element.
Going across the first row shell 1 is filled with two electrons in a 1s subshell.
Going across the second row the orbitals in shell 2 are filled with eight electrons (two in the 2s subshell and six in the 2p subshell).
Going across the third row electrons are added first to the orbitals in the 3s subshell and then to the orbitals in the 3p subshell.
The process is stopped when you reach the symbol for the element because at that point all of its available electrons have been assigned to subshells.
Going across the second row the orbitals in shell 2 are filled with eight electrons (two in the 2s subshell and six in the 2p subshell).
The periodic table shows that the 2s orbitals are occupied before electrons are added to the 2p orbitals.
Going across the third row electrons are added first to the orbitals in the 3s subshell and then to the orbitals in the 3p subshell.
The process is stopped when you reach the symbol for the element because at that point all of its available electrons have been assigned to subshells.