Everything Science Grade 10

CHAPTER 5. THE PERIODIC TABLE 5.1

s-block

d-block

p-block

group number

1

(^2) 13 14 15 16 17
18
We also note that the period number gives the energy level that is being filled. For example,
phosphorus (P) is in the third period and group 15. Looking at the figure above, we see
that the p-orbital is being filled. Also the third energy level is being filled. So its electron
configuration is: [Ne] 3 s^23 p^3. (Phosphorus is in the third group in the p-block, so it must
have 3 electrons in the p shell.)
Periods in the periodic table ESABO
The following diagram illustrates some of the key trends in the periods:
period number
1 2 3 4 5 6 7
Atomic radius
Ionization energy
Electronegativity
Figure 5.2: Trends on the periodic table.
See video: VParr at http://www.everythingscience.co.za
Table 5.1 summarises the patterns or trends in the properties of the elements in period 3.
Similar trends are observed in the other periods of the periodic table. The chlorides are
compounds with chlorine and the oxides are compounds with oxygen.
Chemistry: Matter and materials 97