1. Alkali Metals
Noadswood Science, 2013

2. Alkali Metals To know the properties of the alkali metals
Tuesday, June 19, 2018
Alkali Metals
To know the properties of the alkali metals

3. Reactivity
Some metals are extremely reactive, whilst others are not – the reactivity series shows how reactive metals are…
Potassium
Sodium
Calcium
Magnesium
Aluminium
(Carbon)
Zinc
Iron
Lead
(Hydrogen)
Copper
Silver
Gold
Platinum

4. Reactivity
Compare the reactivity series to where the elements are found within the periodic table – what relationship is there?

5. Electron Structure & Reactivity
There is a definite pattern between the placement of a metal on the periodic table and how reactive it is – the most reactive metals are located in groups I and II, with the least reactive metals being within the transition metals, placed in the centre of the periodic table, between groups II and III – they are generally hard and dense, and less reactive than the alkali metals

6. Reactivity – Very Reactive
The electron structure of an atom affects how reactive it is – a shell with just one electron in is it keen to ‘get rid’ of this so they have a full outer shell
Elements within group I (lithium, sodium, potassium etc…) and group II (magnesium, calcium, strontium etc…) have just one or two electrons to ‘get rid of’ before they have a full outer shell, and as such are extremely reactive
The most reactive metals are found within group I and II

7. Shells
Electrons which orbit the nucleus of an atom occupy specific shells – the follow some specific rules: -
Electrons always occupy shells (energy levels)
The lowest energy levels are always filled up first
Only a certain number of electrons are allowed in each shell (1st shell = 2; 2nd shell = 8; 3rd shell = 8; 4th shell = 18)
In most atoms the outer shell is not full, making them want to react

8. Electron Structure
The electronic structure of an atom is a description of how the electrons are arranged - you need to be able to describe the electronic structure of the first 20 elements in the periodic table...
The first 20 elements in the periodic table run from hydrogen to calcium

9. Electron Structure
The periodic table can be used to work out an electronic structure: -
Find the element in the periodic table
Work out which period it is in, and draw that number of circles around the nucleus
Work out which group the element is in and draw that number of electrons in the outer circle - with eight for Group 0 elements (except helium)
Fill the other circles with electrons (2 in the first, 8 in the second and third, and 18 in the fourth)
Finally, count your electrons and check that they equal the atomic number

10. Lithium
For example, work out the atomic structure of Lithium...

11. Lithium
Lithium - 2nd period so it has 2 circles drawn around it and in group 1 so it has 1 electrons in the outer shell...

12. Lithium
Lithium (Li) - 2,1 (three electrons (2 in shell 1 and 1 in shell 2))

13. Alkali Metals
Elements in group 1 are known as the alkali metals – they are very reactive and have the following properties as you go down the group: -
They become more reactive (outer e- further from nucleus)
They have lower melting points
 They have lower boiling points
They have a low density (Li, Na and K less dense than water)

14. Alkali Metals & Water
Alkali metals react vigorously with water, producing hydrogen gas and form hydroxides that dissolve producing alkaline solutions
2Na (s) + 2H2O (l)  2NaOH (aq) + H2 (g)
2K (s) + 2H2O (l)  2KOH (aq) + H2 (g)