Module 3, Section 1 Flashcards
Define periodicity.
Repeating trends in physical and chemical properties of elements across each period.
KEY DEFINITION:
1st ionisation energy
Energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms
How does nuclear charge affect ionisation energies?
More protons in nucleus, greater attraction between nucleus and electrons.
How does atomic radius affect ionisation energies?
Attraction decreases with distance. Electrons close to nucleus means stronger attraction.
How does shielding affect ionisation energies?
Lessening of the nucleus pull by inner shells
Explain the drop in ionisation energy between Group 5 and 6.
The outer electron in nitrogen is removed from a singly occupied shell, while in oxygen it is removed from an orbital containing two electrons. This repulsion means removal of electron doesn’t require as much energy.
Write an equation to show the effect of indigestion tablets.
Mg(OH) 2 + 2HCL = 2H2O + MgCl2
Write an equation to show the production of bleach.
2NaOH + Cl2 = NaClO + NaCl + H2O
What is the test for carbonates?
Add dilute hydrochloric acid, if CO2 is formed carbonate ions are present. CaCO3 + 2HCl = CaCl2 + H2O + CO2
Describe the test for sulfates.
Add dilute HCl followed by barium chloride, a white precipitate shows the presence of sulfate ions. Na2SO4 + BaCl2 = BaSO4 + 2NaCl
How do you test for chloride ions?
A white precipitate is formed, which is soluble in dilute NH3
How do you test for bromide ions?
A cream precipitate is formed, soluble in conc. NH3
How do you test for iodide ions?
A yellow precipitate is formed, insoluble in NH3
