Finding the last occupied sublevel of an element requires locating it on the periodic table, understanding where each block resides, and understanding how
sublevels relate to the periods of the periodic table for each block.
Abbreviated electron configurations
Abbreviated electron configurations use a bracketed chemical symbol (to represent the electron configurations) of a noble gas (group 8A or 18) as the starting point
for an electron configuration for an element in the next row after whichever noble gas is chosen.
For example, the abbreviated electron configuration for scandium would be
as opposed to
Match each complete or abbreviated electron configuration with the element it corresponds to, assuming that each configuration is for a neutral atom.
Drag the appropriate items to their appropriate bins.
How to approach the problem
There are two methods for identifying an element based on a given electron configuration. One is to locate the last occupied sublevel and count down
the period the correct number of electrons. For example, the last occupied block sublevel for the electron configuration
is the 4
sublevel. Since the exponent following 4
is 1, then the first element in this sublevel block is the element matching this electron configuration. In this
case, the element is potassium (
The second method involves adding the electrons represented by the exponents in the electron configurations. For example, the electron configuration
displays 8 electrons (2 + 2 + 4 = 8). Thus, this electron configuration corresponds to the element with an atomic number of 8, oxygen
For abbreviated electron configurations, add the exponents to the atomic number of the noble gas being referenced. For example, the electron
has 10 + 2 + 5 = 17 electrons. The element corresponding to this electron configuration is chlorine (
Determine how many electrons are represented in an electron configuration
How many electrons are represented by the following electron configuration: