Here we are sharing most important focus area based notes of SSLC Kerala,that helps to improve their performance in public examination


馃攨In an atom there are main energy level called shells and sub energy levels
called sub shells.

馃攨The number of sub shells in each energy level is equal to its shell number.

馃攨There are 4 sub shells-s,p,d,f

馃攨 s sub shells can accommodate 1 to 2 electrons

馃攨 p sub shells can accommodate 1 to 6 electrons

馃攨 d sub shells can accommodate 1 to 10 electrons

馃攨 f sub shells can accommodate 1 to 14 electrons

馃攨1s<2s <2p<3s<3p<4s<3d<4p<5s<4d<5p<6s鈥︹︹︹

馃攨 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s鈥︹︹︹︹︹︹.

馃攨 The electrons in an atom are distributed in the increasing order of the energies of sub
shells. This is called sub shell electronic configuration.

馃攨The maximum number of electrons accommodated in each sub shells s-2, p-6, d-10,f-14.

馃攨While writing the sub shell electronic configuration of elements with higher atomic numbers, the symbol of the noble gas preceding that element may be shown with in square brackets followed by the electronic configuration of the remaining sub shells.

馃攨Period number is equal to the highest shell number in the sub shell electronic configuration.

Group number

馃攨s-block 鈫 The no. of electrons in the outer most s sub shell

馃攨p-block 鈫 by adding 10 to the total number of electrons in the s and p sub shells of
the outer most shell.

馃攨13 to 18 group elements are present in p Block
馃攨1 to 6 electrons are present in p subshell
馃攨Elements in the solid, liquid and gaseous state at room
temperature are included in this block
馃攨In p block elements , less reactive elements(more stable
elements) are present in the 18 th group (Noble gases)
馃攨 Elements with Positive and negative oxidation state are
present in p block
馃攨P block elements usually show higher ionization energy
than the s block elements.
馃攨 In p block elements, the highly reactive elements are

馃攨d-block 鈫 adding the total number of electrons in the outer most s sub shell and
preceding inner d sub shell

馃攨Transition elements forms coloured salts ; the colour is due to the presence
of transition element ion

馃攨lanthanoids and actinoids are two periods of elaements of f block

馃攨Most of the actinoids are radioactive and are artificial elements


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