Module 3: Chapter 8 - Reactivity Trends Flashcards
(87 cards)
How does 1st Ionisation energy change down group 2?
It decerases as both the atomic radius and electron shielding increases causing a weaker attraction from nucleus to electron in the outer shell. Therefore there is a lower ionisation energy down the group
How does melting point change down group 2?
Melting point decreases as there is weaker metallic bonding. There is the same number of delocalised valence electrons, however the metal ions are larger causing weaker attraction between the positive metal ions and delocalised valence electrons. Therefore lower melting points. There is a change in trend after Mg due to a change in the way ions pack together
How does atomic radius change down group 2?
Atomic radius increases down the group due to more electron shells
What is the observation of Magnesium with water?
- Very slow reaction with cold water
- Reaction with steam - burns witha. white flame to form white powder
What is the observation of Calcium with water?
effervesence in water and forms a white solid
What is the observation of Strontium with water?
Vigorous effercesence in water forming a colourless solution
What is the observation of Barium with water?
Extremely vigrorous effervesence in water forming a colourless solution
What is the observation of berrylium with water?
No reaction
What is the equation for the reaction of Magnesium with water?
- Cold water: Mg + 2H₂O -> Mg(OH)₂ + H₂
- Steam: Mg + H₂O -> MgO + H₂
What is the equation for the reaction of calcium with water?
Ca + 2H₂O -> Ca(OH)₂ + H₂
What is the equation for the reaction of strontium with water?
Sr + 2H₂O -> Sr(OH)₂ + H₂
What is the equation for the reaction of Barium with water?
Ba + 2H₂O -> Ba(OH)₂ + H₂
What is the trend in reactivity of group 2?
increases down the group
Why are group 2 metals reducing agents?
They can lose electrons, donating them to other species
Why do group 2 metals become more reactive down the group?
As you travel down group 2, both the first and second ionisation energies decrease causing reactivity to increase. This is because there is a greater atomic radius and greater electron shielding causing the nuclear attraction on the valence electrons to decrease
How is ionisation energy proportional to reactivity?
Inversly proportional, the lower the ionisation energy, the higher the reactivity
What is the most common type of reaction of a group 2 element and why?
Redox, each group 2 element contains 2 electrons in the outer s sub-shell meaning each metal ion can be easily oxidised, losing 2 electrons to form a 2+ ion.
What is the reaction of group 2 elements with oxygen?
Group 2 elements react with oxygen to form a metal oxide
What is the reaction of magnesium with oxygen?
2Mg + O₂ -> 2MgO
What are the observations of the reaction of magneisum with oxygen?
The magnsium burns with a brilliant white light forming a white powder
What is the reaction of a group 2 metal with a dilute acid?
Metal + acid -> salt + hydrogen
What is the reaction of group 2 oxides with water?
The oxides of group 2 elements react with water, releasing hydroxide ions, forming a solution of the metal hydroxide. As the group 2 hydroxides are only slightly soluble in water, when the solution becomes saturated any further metal and hydroxide ions form a solid precipitate
Metal oxide + water -> Metal hydroxide
What is the reaction of calcium oxide with water?
CaO(s) + H₂O(l) -> Ca(OH)₂(s)
What is the solubility of group 2 hydroxides?
The solubility of group 2 hydroxides increases down the group