3.1.2 Atomic Raidus & Group 2 Element Flashcards
What is atomic radius
its the distance between the nucleus and the outer electron
Pattern of atomic raidus across a period
Decreases
> Nuclear charge increases so more protons
> Stronger attraction between the outer e- and nucleus
> Which causes the radii to get smaller however the same electron shielding
Pattern of atomic radius down a groups
Increases
> More shells therefore more distance between nucleus and the outer e-
> Nuclear charge increases the other two factors outweigh it
atomic radii increases as there more shells therefore more electron shielding which causes the radius to get bigger
What are the physical properties
> High melting and nailing points
Are light metals with low densities
Form colourless compounds
what happens as you move down group 2
atomic radii increases as there more shells therefore more electron shielding which causes the radius to get bigger
what happens to the reactivity as you move down group 2
Reactivity increase:
> Each succesive element has its outer electron in a higher energy level
> Larger atomic radius
> Feels more shielding from the positive pull of the nucleus
Group 2 elements & oxygen
2Ca (G) + O2(G) –>
2CaO (S)
Mo/M(OH)2 + acid –>
salt + water
thermally decomposes–>
metal oxide + co2 + h2o
Group 2 elements & water
Ca (S) + 2H2O (L) –>
Ca(OH)2 (AQ) + H2 (G)
Group 2 elements & dilute acids
Ca(S) + 2HCl (AQ) –>
CaCl2 +H2
What is the trend in alkalinity as you go down
> Solubility increases
pH increases
Alkalinity increases
Equation of calcium hydroxide neutralising acids in the soil, forming neutral water
Ca(OH)2 (S) + 2H+ (AQ) –> CA^2+ (AQ) + 2H2o (L)
Uses of Ca(OH)2 in agriculture
Its added to fields by farers to increase the pH of acidic soils
uses of groups 2 compounds in medicine
Group 2 bases are often used as antacids for treating acid indigestion
