Group 2
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What are elements in group 2 also known as? Why?
Alkaline earth metals. Their hydroxides mand oxides are alkaline.
Describe the electron arrangement in group 2 elements.
2 electrons in their outer s orbital. S orbital gets further from the nucleus as you go down the group.
Describe the sizes of the atoms of group 2 elements.
Atoms get bigger going down the group. Atomic radii increase down the group. Number of shells increase down the group.
Describe the melting points of group 2 elements.
Giant metallic structure. Going down the group, the sea of delocalised electrons are further from the nucleus. As a result, the strength of the metallic bonds decrease as you go down the group. Melting points of group 2 elements decrease down the group from calcium.
Describe the trend in first and second ionisation energy down group 2.
Decrease down the group. Takes less energy to remove the electrons as they become further away from the positive nucleus. Nucleus is more effectively shielded by more inner shells of electrons. Weaker attraction between the nucleus and outer electron.
Describe the trend in reactivity down group 2.
Increases down the group. Increased electron shielding makes the electron easier to lose.
What is magnesium hydroxide also known as?
Milk of magnesia
What is magnesium hydroxide used for?
Indigestion. Neutralise excess stomach acid.
Describe the reaction between magnesium and warm water.
Very slow.
Describe the reaction between magnesium and steam.
Rapid. Mg (s) + H2O (g) -> MgO (s) + H2 (g)
What is calcium hydroxide also known as?
Slaked lime.
What is calcium hydroxide used for?
Treating acidic soil which is essential for good crop production and maintaining the food supply. This is important for agriculture to change soil pH.
What is the trend in solubility of hydroxides?
Solubility increases down the group.
How do the group 2 hydroxides all look?
White solids
What is the trend in solubility of sulfates?
Decreases down the group.
What is barium sulfate also known as?
Barium meal
What is barium sulfate used for?
Outlining the gut in medical-xrays. Barium hydroxide is virtually insoluble so it is safe.
What ions do group 2 metals form?
They lose 2 electrons to form 2+ metal ions.
What kind of reaction is the group 2 metals reacting with water?
Redox
What is formed when group 2 metals react with water?
Metal hydroxide and hydrogen
What is the equation for magnesium with warm water?
Mg + 2H2O -> Mg(OH)2 + H2
Why is magnesium reacting with steam much faster than magnesium with warm water?
Steam provides the reaction with extra energy.
What is observed when magnesium reacts with steam?
Magnesium burns with a bright white flame to form hydrogen and magnesium oxide (a white powder).
What is barium chloride used for?
Testing for sulfate ions. Add your sample to HCl to acidify the solution then add BaCl2. White precipitate will form if sulfate ions are present. It reacts to form barium sulfate which forms a white precipitate when sulfate ions are present. Ba^2+ + SO4^2- -> BaSO4