The Periodic Table

Question 1

Development of the periodic table

Answer 1

• Used to be arranged in order of relative atomic mass.
• Mendeleev left gaps in his table where the next element didn’t seem to fit.
• By putting gaps he could keep elements with similar chemical propertied in the same group.

Question 2

Modern periodic table

Answer 2

• Produced by Henry Moseley and he arranged elements according to increasing atomic number rather than atomic mass.

Question 3

Arrangement of elements

Answer 3

• Periodic table is arranged into periods (rows) and groups (columns).
• All elements in a period have same no. of electron shells which results in repeating patterns of physical and chemical properties across a period. This is called PERIODICITY.

Question 4

Electron configuration

Answer 4

• Each period starts with an electron in a new highest energy shell.
• Elements in each group have atoms with the same no. of electrons in each sub shell. This similarity in electron configuration gives elements in the same group their similar chemistry.
• The elements in the periodic table can be divided into blocks corresponding to their highest energy sub-shell: s,p,d and f

Question 5

Group names

Answer 5

Group 1: alkali metals
Group 2: Alkaline earth metals
Group 17: Halogens
Group 18; Noble gases