Name the elements in Period 1.

What is the common feature of the electronic configuration of the elements at the end of Period 2 and Period 3 ?

Supply the missing word from those in brackets: If an element has one electron in it's outermost energy level [shell] then it is likely to be …………… [metallic / non- metallic].

Copy and complete the following sentences choosing the correct word or words from those given in brackets at the end of each sentence :

The similarities in the properties of a group of elements is because they have the same …………… [electronic configurations, number of outer electrons, atomic numbers.]