The periodic table and transition metals GapFill

In the periodic table, elements are ordered by their  reactivityhardnessatomic numbercolouratomic massconductivity. Columns in the periodic table are called  periodssetsserieselemental regionsgroupsclasses, and all the elements in the same column have similar reactions because they have the same number of  electronsatomsisotopesneutronsprotonsions in their outer shell. Over time, new ways of organising elements have been invented. Elements were first put in order by atomic weight, but some elements were in the wrong group.  Linus PaulingAlfred NobelMax PlanckIsaac NewtonErnest RutherfordDmitri Mendeleev changed the order and left gaps for  radioactiveunreactivemagneticuselessdangerousundiscovered elements, based on the chemical properties of the elements.

Elements which form positive ions when they react are called metals, and elements which do not form positive ions when they react are called  alloysionsnon-metalssaltscarbonatesnoble gases. Group 0 elements are known as the  non-metallic gasesnoble gasestransition gasesneon gasesalkali gasesunreactants and do not usually react. Their boiling point increases down the group. Group 1 elements are called the  metalliumsmicrometalsreactant metalsnoble metalsalkali metalsmetallogens and react with oxygen, chlorine and water. Their reactivity increases down the group. Group 7 elements are known as the halogens. A more reactive halogen  displacesincorporatesreplacesdissolvesovercomessolidifies less reactive halogens in a solution.

 MedialAlkaliMetamorphicConversionTransitionEssential metals are in the central block of the periodic table. They are metals, but they have very different chemical and physical properties from the metals in Group 1. For example:

• they are  more reactivemore fluidmore stablehardermore conductivemore brittle
• they change state at a higher temperature, so have higher melting points
• their strength is higher, so they are often used in construction
• they react less vigorously with oxygen,  carbon dioxidesulfurhydrogenacidsbaseswater and halogens

They can often be used as  enzymesendothermsmagnetssolventscatalystsreagents to speed up reactions. They can also form  electroniccovalentnegativearomaticreflectivecoloured compounds, and have ions with different  shapesmagnetic propertiesenergy levelschargessizesnumbers of protons.