Group 2
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
卡片预览 (14 张)
Group 2 reactivity
Increases down group
Why
Atomic radius increases, more shells Shielding increases Nuclear attraction decreases Increased nuclear charge is outweighed by increase in Shielding/radius Electrons more easily removed Ionisation energy decreases
Melting point
Decreases down group Weaker metallic bonding Metal ions have a larger ionic radius So lower melting points
+ oxygen
Metal + oxygen > metal oxide
+ water
Metal + water > metal hydroxide + hydrogen
+ dilute acid
Metal + dilute acid > salt + hydrogen
Uses
Antacid - milk of magnesia, Mg(OH)2, neutralises acid, alkaline Antacid - limestone/calcium carbonate, CaCO3, base, neutralises acid Slaked lime - agriculture, Ca(OH)2, neutralises acidic soil
pH
Increases down group More alkaline
HCl + Mg(OH)2
2HCl + Mg(OH)2 > MgCl2 + 2H2O
Acid + base
> salt + water
HCl + CaCO3
2HCl + CaCO3 > CaCl2 + H2O + CO2
Why does reactivity increase down the group (3)
Atomic radius increases More electron shielding Weaker nuclear attraction towards electron in the outer shell Ionisation energy decreases; less energy required to remove electron
Identify metal
Mol = vol/24 Mol= gram / RAM
Experiment repeated using same mass of a group 2 metal from further down the group Predict whether volume of hydrogen produced would be greater, less or equal to volume produced in first experiment
Less as fewer moles of metal reacting