Group II Flashcards
What is the definition of an s-block element
An element which has an atom with the highest energy/outer shell electron in an s subshell
What are he physical properties of group II metals
- atomic radius increases as group descends
- 1st ionisation energetic decreases as you descend group - increased radius and shielding
What is the equation when metal oxides react with water
Metal oxide + water = metal hydroxide
What is the equation when metal oxides react with acid
Metal oxide + acid = salt + water
State two uses of group II compounds
⭕️ MgO - cure indigestion - reacts with excess stomach acid
⭕️ CaCO3 - toothpaste - neutralises acid on teeth
What is a use of calcium carbonate
Makes limewater:
Limestone heated - thermal decomposition to calcium oxide
Calcium oxide mixed with water to form calcium hydroxide (limewater)
What is cement made of
Calcium oxide and silica
What happens when water is added to calcium oxide and silica
Makes calcium silicate
What happens when aluminium oxide reacts with calcium oxide
Makes calcium aluminate
What happens when water evaporates from calcium silicate and calcium aluminate
They crystallise and form solid cement
What is concrete
Cement with gravel and more sand added
What is the equation for the thermal decomposition of metal carbonate
Metal carbonate ➡️ metal oxide + carbon dioxide
What is the trend for decomposition temperature as you descend group II
Increases down group
Why does thermal decomposition temperature increase down group II carbonates and hydroxides
- Size of cation increases
- Charge density decreases
- Cation less able to polarise and destabilise carbonate ion
- therefore more thermally stable
What is the general equation for the decomposition of metal hydroxides
Metal hydroxide ➡️ metal oxide + water
What is the trend for thermal decomposition temperature for metal hydroxides as you move down group II
Increases
What is the trend of solubility of group II sulphates as you move down the group
Solubility decreases down group
What is the trend of solubility of group II hydroxides as you move down the group
Solubility of hydroxides increases down the group
What happens to the solubility of solids as temperature increases
Solubility increases
What happens to gaseous solutes as temperature increases
Solubility decreases
What is the trend for reactivity we you go down group II
Increases
What is the general equation for the reaction of steam with a group II metal. Also write the general symbol equation
Metal + steam = metal oxide + hydrogen
See page 87 revision book
What colour will magnesium burn with steam
White light
What colour does calcium burn with when reacted with steam
Red
What colour does strontium burn when reacted with steam
Red flame
What colour does barium burn with when reacted with steam
Green
What is the general equation for the reaction of group II elements with water. Write the symbol equation also
Metal + water = metal hydroxide + hydrogen
See page 87 rev book for symbol equation
What are the observations when Mg reacts with water
Bubble very slowly
Metal dulls in appearance
What are general observations for Ca, Sr and abs when they react with water
Bubbles
Heat
Eventually disappear
What are the observations when calcium reacts with cold water
Gives sparingly soluble white hydroxide
Sinks and rises
What are the observations when Sr reacts with cold water
Vigorous
Gives sparingly soluble white hydroxide - completely soluble in hot water
What are the observations when Ba reacts with water
V vigorous
Forms white hydroxide- moderately soluble in water
What is the general equation when group II elements react with oxygen. Write the symbol version too
Metal + oxygen ➡️ metal oxide
See page 86 revision book
What are the observations for Mg, Ca, Sr and Ba when they react with oxygen
All produce white powder Mg = bright white light Ca = brick red flame Sr = red flame Ba = green flame
What is the general and symbol equation for the reaction between group II elements and acids. (Both HCl and H2SO4)
Metal + acid = metal salt + hydrogen
See page 88 rev book
What are the observations for the reaction of group II metal and acid
Heat released
Bubbles
Metal disappears
Colourless solution formed
