all Flashcards
why did mendeleev’s periodic table become more widely accepted then previous versions ?
mendeleev predicted properties of missing elements
elements were discovered that filled the spaces
properties matched mendeleevs predictions
in the modern periodic table, how are elements arranged ?
in order of atomic number
what would you see when sodium reacts with chlorine ?
flame
white powder
calcium + ___________ acid –> calcium chloride + _____
hydrochloric
water
name the equipment used in titrations
sodium hydroxide
conical flask
burette
why do nanoparticles cost less than fine particles ?
nanoparticles have a lower surface area to volume ratio
less can be used for the same effect
what is the relative mass of a neutron ?
1
what is the relative charge of a neutron ?
0
what is the relative mass of a proto ?
1
what is the relative charge of a proton ?
+1
why is the mass number in isotopes different ?
they have different numbers of neutrons
explain why reactions are exothermic
the products have less energy then the reactants -SO- energy is released
what are two control variables in an experiment when electrodes are changed in an electrolyte
temperature of solution
concentration of electrolyte
compounds/ions in electrolyte
why are hydrogen fuelled trains referred to as the new steam trains ?
in a hydrogen fuel cell hydrogen is oxidised and water vapor is produced
explain why mixtures are used as electrolytes
mixtures have lower melting points –> less energy needed
