The periodic table has (i) 18 groups of elements, plus a block of (ii) transition metals. The groups are numbered. Group 4 contains the elements carbon (C), silicon (Si), germanium (Ge), Tin (

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The periodic table has (i) 18 groups of elements, plus a block of (ii) transition metals. The groups are numbered. Group 4 contains the elements carbon (C), silicon (Si), germanium (Ge), Tin (Sn) and lead (Pb). Their atoms each have 4 electrons in the outer shell. The atoms of group 5 elements each have 5 electrons in the outer shell and so on. Some of the groups have special names too. Group 1 is often called the (iii) alkali metals, group 2 is the alkaline earth metals, group 7 is the (iv) halogens and group 0 is the (v) noble gases.

The horizontal rows in the table are called (vi) periods. Period 2 contains lithium (Li), beryllium (Be), boron (B), carbon (C), nitrogen (N), oxygen (O), fluorine (F) and neon (Ne). There's a zigzag line through the groups. It separates the metals from the non-metals. The (vii) metals are on the left.