2019 mistakes Flashcards
(12 cards)
Why did mendeleev’s periodic table become more widely accepted than previous versions?
Mendeleev had predicted properties of missing elements
Elements were discovered that filled the gaps
Properties of these elements matched Mendeleev’s
Describe what you would see when group 1 metals react with chlorine
Flame
White solid forms
Colour of chlorine gas fades
Alpha particle scattering experiment
Most of the alpha particles passed through the gold foil
So the mass of the atom is concentrated in the center and most of the atom is empty space
Some alpha particles were deflected
So atom had a positively charged center
Structure of ammonia?
Simple molecular structure
Explain why a reaction is exothermic
The products have less energy than the reactants
Energy is released to the surroundings
Hydrogen fuel cells- steam trains?
Hydrogen is oxidised and water is produced as water vapour
Aluminium oxide electrolysis - explain why the positive electrode must be continually replaced
Électrode reacts with oxygen
The electrode is graphite
So carbon dioxide is produced
Explain why sodium chloride solution cannot be used as the electrolyte to produce sodium metal
Hydrogen would be produced as sodium is more reactive than hydrogen
Explain why the excess hydrogen must be burned off
Prevent hydrogen gas escaping into the air
Hydrogen is explosive/flammable
How did the discovery of isotopes confirm that Mendeleev was correct not to place elements in a strict order of atomic weight
Isotopes of the same element have different masses but have the same chemical properties so occupy the same position on the periodic table
alkali me
Simpl
