Electrons and groups
A section of the periodic table
Columns in the periodic table – groups
- The vertical columns in the A tabular representation of all known elements in order based on atomic number, eg all the noble gases are found on the right of the periodic table. are called groups.
- The A substance made of one type of atom only. in any one vertical column are in the same group.
- The groups are numbered from left to right.
- Elements in the same group have similar chemical The characteristics of something. In chemistry, chemical properties include the reactions a substance can take part in. Physical properties include colour and boiling point..
- The number of Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons. in the outer shell of all the elements in a group is the same as the group number.
Examples
- All the Group 1 elements – lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs) and francium (Fr) – have one electron in the outer shell.
- The Group 7 elements – fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (At) – have seven electrons in the outer shell.
- Group 0 elements – helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn) – have full outer shells. (Group 0 is sometimes called Group 8).
Rows in the periodic table – periods
Elements in the same horizontal row are in the same period. The periods are numbered from top to bottom.
The period number is the same as the number of occupied electron shells.