Elements

• Noble gases - group 0, fairly unreactive
• group 0 has 0 reactivity because they are inert and do not react with other elements
• Group 1 is Alkali metals. They are soft and have low melting and boiling points.
• Group 1 is very reactive and increases down the group.
• Group 7 is the halogens, which are non-metals.
• Group 7 elements are highly reactive
• Transition metals are in the middle of the table. they have no group number
• Most reactive - Potassium , sodium , lithium, calcium
• least reactive - gold, silver, mercury, copper
• Mendeleev sorted elements into groups then columns based on their properties.

  He left gaps where certain elements didn't fit the pattern.

  He predicted the properties of undiscovered elements