TOPIC 4 - INORGANIC Flashcards
(14 cards)
understand reasons for the trend in ionisation energy down Group 2
Decreases down the group, down the group has an extra shell, more shielding means further away from nucleus , so easier to remove , reactivity increases down the group.
understand reasons for the trend in reactivity of the Group 2 elements down the group
Reactivity increases as the ionisation energy decreases so electrons are lost more easily
know the reactions of the elements Mg to Ba in Group 2 with oxygen, chlorine and water
React with water to form a metal hydroxide and hydrogen
React with oxygen to form a solid white oxide
React with chlorine to produce a solid white chloride (be no reaction ba rapid)
know the trends in solubility of the hydroxides and sulfates of Group 2 elements
Singly charged negative ions increase in solubility down the group (hydroxides)
Doubly charged negative ions decreases in solubility down the group (sulfates)
Barium sulfate is insoluble, magnesium hydroxide has a low solubility (aka sparingly solvable)
understand experimental procedures to show
Nitrates - how long it takes til a certain amount of 02 is produced (glowing splint) / how long it takes til brown gas is produced (no2 toxic fume cupboard )
Carbonates-how long it takes till amount of c02 is produced , use limewater turns cloudy.
understand the formation of characteristic flame colours by Group 1 and 2 compounds in terms of electron transitions
Students will be expected to know the flame colours for Groups 1 and 2 compounds
Energy absorbed causes electrons to move to a higher energy level. Colours are seen when electron falls back down to lower energy level releasing visible light. The difference in energy between the higher and lower levels determines wavelength of light , which determines the colour shown on electromagnetic spectrum
Colours of flames
Li-red
Na-orange/yellow
K- lilac
Rb-red
Cs-blue
Ca- birck red
Sr-crimson
Ba-green
Why does magnesium not produce a flame colour
No emission of light /energy in the visible region of the spectrum
understand experimental procedures to show: flame colours in compounds of Group 1 and 2 elements
Dip a piece of nichrome/ platinum wire into HCl and then heat in the flame to clean it
Dip the wire into the unknown compound and then put in the cone part of the blue flame , note the colour shown.
understand reasons for the trends in melting and boiling temperatures, physical state at room temperature, and electronegativity for Group 7 elements
Mb +bp - increases down the group , there’s an increases in electron shells so more electrons, the London forces between the halogen molecules get stronger. Increase in london forces make it harder to overcome the intermolecular forced so mp and bp increase , fluorine and astatine fit with the trends
understand reasons for the trends in melting and boiling temperatures, physical state at room temperature, and electronegativity for Group 7 elements
Halogens exists as covalent diatomic molecules bcs they’re non polar they have low solubility
-do disolve in organic molecules eg hexaneElectronegativity is a measure of how well an atom attracts electrons in a covalent bond , electronegativity decreases decreases down group 7 due to the increase in the number of electron shells and the increase between the nucleus and bonding electrons
understand reasons for the trend in reactivity of Group 7 elements down the group
halogens are oxidising agents as they gain electrons in their outer p shell
-atoms become larger down the group so outer electrons are further away, outer electrons are also shielded more from the nucleus , larger atoms are less reactive and and reactivity decreases down the group
understand the trend in reactivity of Group 7 elements in terms of the redox reactions of Cl2, Br2 and I2 with halide ions in aqueous solution, followed by the addition of an organic solvent
As the Group 7 elements cause the oxidation of other compounds or elements we say it is a good Oxidising agent. Reactivity decreases as you go down the Group. This means they gain their electrons less readily. This means as you go down Group 7, their oxidising power decreases. a more reactive halogen will displace a less reactive one
test for ammonium ions
add few drops of dilute sodium hydroxide solution then warm gently - damp red litmus paper turns blue
