Valence configuration and the periodic table

Look again carefully at the group configurations. They are really easy if you understand the filling of the subshells and know your periodic table.

s1	s2											p1	p2	p3	p4	p5	p6
							1 H
3Li	4Be											5B	6C	7N	8O	9F	10Ne
11Na	12Mg											13Al	14Si	15P	16S	17Cl	18Ar
19K	20Ca	21Sc	22Ti	23V	24Cr	25Mn	26Fe	27Co	28Ni	29Cu	30Zn	31Ga	32Ge	33As	34Se	35Br	36Kr
37Rb	38Sr	39Y	40Zr	41Nb	42Mo	43Tc	44Ru	45Rh	46Pd	47Ag	48Cd	49In	50Sn	51Sb	52Te	53I	54Xe
55Cs	56Ba	71Lu	72Hf	73Ta	74W	75Re	76Os	77Ir	78Pt	79Au	80Hg	81Tl	82Pb	83Bi	84Po	85At	86Rn
s-block nsx x 1 - 2		d-block ns2(n-1)dx (x is 1- 10)										p-block ns2 npx (x is 1-6)

The shell number (given by n) in which the valence electrons are found is given by the period number for s and p block elements.
 

For d block elements the n for s electrons equals the period number, and the n for d-electrons equals (period number -1).