Every day last week I posted about each element in the first column of the periodic table to mark the International Year of the Periodic Table on my instagram account. Elements are grouped in columns based on their properties and in this post I’ll talk about how the group 1 elements are chemically similar.
On the extreme left of the periodic table lie the alkali metals. Alkali because when they come into contact with water they form alkaline species e.g. lithium forms lithium hydroxide.
Hydrogen is a bit of an anomaly for this group but technically belongs to group 1 because like its fellow members, it only has one outer shell electron, known as a valence electron, available to interact with other atoms.
This single electron is what makes these elements so reactive because atoms prefer to have full stable complements of electrons and they are eager to rid themselves of this electron, which is relatively easy to do, in order to gain a more stable electron configuration.
Aside from hydrogen, alkali metals are soft metals that react with air and water, meaning they are rather fun to through into a lake. When they react with water they release hydrogen gas, some in more violent ways than others.
Their flammability and reactivity increase going down the table. The YouTube channel Periodic Videos have some really nice videos demonstrating these reactions.
Lithium is a slow burner and takes its time converting to its metal hydroxide. Sodium will fizz while potassium bursts into violet flames. Rubidium and caesium explode when they contact water while francium is too radioactive and usually explodes without needing to be hydrated.
Alkali metals also react with oxygen to form metal oxides, or in the case of hydrogen, forms water, one of the key molecules of life. We are made up of 55-60% water.
They also react with halogens (group 7 elements) to form salts such as sodium chloride which we enjoy on all manner of foodstuffs. Lithium powers our laptops and cars, potassium and sodium keep the electronic signals from our brain to our body in check and rubidium and caesium help keep us on time through their use in atomic clocks.
Next we shall move across the periodic table to group 2 to a similar class of elements, known as a the alkali earth metals.
What’s your favourite element? How are you marking #IYPT2019 ? Let me know in the comments below.
The Chemistry of a PhD 