Chemistry: Alkali Metals
What are some observation to know when the reaction between Sodium and water occurs
- Sodium floats because less density - Sodium melts because low melting point - Fizzin cuz hydrogen gas made - Hydrogen not given off symetrically so sodium turns into hovercraft - Sodium is used up in Reaction
What are the main characteristics of Alkali Metals?
1. Their densities TEND to increase down the group 2. Melting points decrease down the group 3. The metals are soft and get softer down the group. They are silver when freshly cut but degrade quickly 4. They are very reactive as you go down the group
What is the formula for Potassium reaction with water
2K(s) + 2H2O(l) —> 2KOH(aq) + H2(g)
Water reaction with sodium
2Na(s) + 3H2O(l) —> 2NaOH(aq) + H2(g)
What is the equation for the reaction of Alkali Metals with oxygen
4M(s) + O2(g) —> 2M2O(s)
Why are the chemical properties of an alkali metal similar?
Because they have the same number of electrons in the outer shell.
What are alkali metals?
Group 1 elements found in the periodic table. They are very reactive, electropositive, monovalent metals forming strongly alkaline hydroxides
What happens to sodium when cut
It becomes shiny but tarnishes quickly
What are all Alkali Metals?
Lithium - Li Sodium - Na Potassium - K Caesium - Cs Francium - Fr
Does Lithium stay as pure Lithium when put in open air?
No, it turns into Lithium Oxide, thats why these elements are stored in oil
What form are group 1 elements
Normally solid but soluble in water
What is the rule for melting points of Alkali Metals
The Melting and Boiling points get lower as you move down the group
How do the metals react with water
The water splits into hydrogen and a hydroxide along with the metal
List 2 reasons why Alkali Metals are in the same group.
They all have 1 electron in their outer shell and they all have similar chemical properties.
What are the chemical properties of Alkali Metals?
They create oxides with the formula M2O (Na2O, K2O) They react with Water to form hydroxides using the formula MOH (LiOH, NaOH) and hydrogen They react with Halogens to form compounds with formula MX (LiCL, KBr) They form ionic compounds which M+ ion (Na+, K+) because metals usually have a positive charge
How and why do Alkali Metals become more reactive as you go down the periodic table?
This is because electrons have less attractive force the farther they are away from the nucleas so they are more easier to react with and lose. As you go down, the elements have more shells so more electrons can be lost easily
True or False: when cut, Lithium tends to tarnish slower than sodium
True, because it reacts slower
True or False: Francium is radioactive
True. No one has ever seen a piece of francium and an isotope is produced by Uranium.
What colour are the Metal ions?
White but can change colour depending on negative ion (Potassium Manganate is Purple because Manganate ion is purple)
How do you store the Alkali Metals
You have to store them under oil or in sealed glass tubes
What are isotopes?
atoms with the same number of protons but different number of neutrons. An example of this is the different isotopes of Uranium
