Higher and foundation tier
The periodic table below has been split into 2 parts. The right-hand side of the table is where the non-metals are found, in groups 3,4,5,6,7 and 0. The left-hand side is where you find the metal, groups 1 and 2 and the centre block called the transition metals is where most of the metals are found. Looking at the periodic table below you can see that around 75 percent of the elements are metals.
The physical properties of an element, that is properties such as melting points, boiling points and densities,
depend to a large extent on the type of bonding present in the element and on its structure. Metals
all have a giant structure of ions, with all the ions held together by strong metallic bonds. A giant
structure with strong bonds will result in elements with high melting and boiling points. The atoms
in most metals are tightly packed together so metals will be dense.
The chemical properties of elements, that is how they react, depends on the number of electrons
in the last shell. This is also related to the position of the element in the periodic table. Elements
react in such a way as to achieve full last electron shells. That is 2 electrons in the case of the
first electron shell and 8 electrons for all other shells. Atoms achieve full shells by losing or
gaining or even sharing electrons.
Metals always lose electrons when they react, e.g. sodium an
alkali metal in group 1 of the periodic
table has an electron arrangement of 2,8,1. To achieve a full last shell it can either gain 7 electrons
or lose 1 electron. Since gaining 7 electrons is not possible it will simply lose one electron to form a
charged atom or ion with a charge of +1.
All alkali metals in group 1 will lose 1 electron when they react, so the metal atoms will form metal
ions with a charge of +1. As you go down a group like the alkali metals from Li, Na, K, Rb, Cs the atoms
get larger as more electron shells are added and the negatively charged electrons in the last shell are
further away from the attraction of the positively charged nucleus and so the electron in the last shell
will require much less energy to remove it, so the metals become more reactive as you descend the group.
The electron in the last shell is also shielded or screened from the protons in the positively charged
nucleus by the addition of extra shells, this also means that less energy is required to remove the
outer electron as more shells are added.
A similar argument can be made for the metals in group2 and 3 of
the periodic table, but remember metals in group 2 will lose 2 electrons and form ions with a 2+ charge and group 3 metals will lose 3 electrons to form ions with a 3+ charge.
There are exception to this broad rule. The alkali metals at the top of group 1 all float on water and so these metals have low densities. The melting and boiling points of group 1 metals are generally much lower that you might expect from metals. The metals in group 1 are not typically what most people think of as metals. The transition metals (shown in red in the periodic table above) on the other hand are hard, strong, shiny metals and are excellent conductors of electricity and heat. These metals are what most think of as a typical metal. The image below summaries the physical properties of metals.
