Fundamentals of chemistry 2 Flashcards
what is an isotope?
isotopes are different forms of the same element, that have the same number of protons, but a different number of neutrons.
what is the pH scale.
a scale to tell how alkaline or acidic something is.
what color does a pH 14 alkaline turn in universal indicator?
purple
acid + metal –> _____+______
acid + metal –> salt+ hydrogen
acid + metal oxide –> _____+_____
acid + metal oxide –> salt+ water
acid + metal carbonate –> ____ + ____
acid + metal carbonate –> salt + carbon dioxide
what is a displacement reaction?
A displacement reaction occurs when a more reactive element displaces, or pushes out, a less reactive element from a compound that contains the less reactive element.
what was rutherfords gold foil experiment?
he fired a beam of alpha particles onto some gold foil surrounds by a substance that flashed when in contact with the alpha particles. when he fired them most went straight through others were deflected back and some of them where redirected off course.
what were rutherfords conclusions from the gold foil experiment?
1)most of an atom is empty space.
2)the center(nucleus) has a positive charge
how do you work out relative atomic mass ?
sum of(an isotope abundance x the isotope mass)
—————————————————-
sum of abundance of all the isotopes
e.g
(69.2 x 63) + (30.8 x 65) / 69.2 + 30.8
what equipment do you need for filtration?
filter paper, filter funnel, conical flask
what equipment do you need for evaporation?
evaporating dish, tripod, gauze, heat proof mat, bunsen burner.
what might simple distillation be used for?
separating out solutions with different boiling points
what is fractional distillation used for?
seperating mixtures of similar boiling points (liquids).
what is a fractionating column?
a tube full of little glass rods that is cooler at the top than the bottom.
what was democritus’ theory in 500 b.c
that everything was made up of things called atoms that could not be separated any further
what was John dalton’s theory
-all matter is composed of atoms
-atoms of each element are the same size, mass ,ect., but are different from atoms of other elements.
-atoms can’t be subdivided(cut) or destroyed
-atoms are tiny solid balls
what did JJ.thomson believe?
he believed that the electrons were like “plums” embedded in a positively charged “pudding”
who did the gold foil experiment?
Ernest Rutherford
what was niels bohr’s theory
he suggested that the electrons orbited the positive nucleus in shells
What part of the atom did James Chadwick discover?
the neutron
what makes a atom stable
a full outer shell
what is the atomic number
the amount of protons (so therefore ,also the amount of electrons).
what are the noble gasses
elements with full outer shells so they don’t really react much
who created the periodic table?
dimiti mendelev.
what is in the top left of an element on the periodic table and what does it tell us?
mass number (number of protons and neutrons)
what does it tell you if an element is in group 2?
that its outer-most shell has 2 electrons in it
what does it tell us if an element is in period 3?
it has three shells
what do you call group 1
alkali metals
what do you call group 7 ?
halogens
what makes something an acid?
any substance that forms an aqueous solution with a pH less than 7
what ions do alkalis form in water?
OH- ions (hydroxide ions)
what products do you get if you react a acid with a base?
salt + water
what does pH scale measure?
the concentration of Hydrogen ions
what makes something more reactive than something else?
how easily it can gain or lose electrons.
what is titration?
a way of figuring out the concentration of an acid by working out the specific amount of alkali that is needed to react with it to neutralise it.
what is the method for titration?
1) use a pipette to transfer 25cm³ of sodium hydroxide solution into a conical flask
2)Add 5 drops of indicator such as Phenolphthalein to the alkali in the conical flask
3)place the conical flask on a white tile so we can see a colour change more clearly
4)fill a burette with sulfuric acid
5)add acid to the alkali until the solution is neutral. we need to add the perfect amount for this to happen. once we start to see a colour change go drop by drop.
6)read the volume of acid added from the burette.
what is the method for making copper sulfate crystals out of copper oxide and sulfuric acid
- Heat up 25cm3 of sulfuric acid until almost boiling, to increase the rate of reaction between the acid and copper oxide.
- Add a small amount of copper oxide using a petri dish and stir slowly with a glass rod. Repeat this until there is clearly powder left at the bottom after stiring, this shows that the acid is fully reacted.
- Using filtration seperate out the excess copper oxide for the copper sulfate solution.
- Place the solution into an evaporating dish and boil at a low temperature until half of the solution remains.
- Leave the solution in the evaporating dish in a cool dry place for 24 hours to fully crystallise.
what is the symbol equation for copper sulfate?
CuSO₄
what is chromatography?
Chromatography is a process for separating components of a mixture.
how does chromatography work
Chromatography is based on the principle where molecules in a mixture are applied onto a surface (stationary phase)and are separating from each other while moving at different speeds with the aid of a mobile phase.
why might one component of a mixture go really high on the chromatography paper.
as it has a greater affinity to the mobile phase than the stationary phase
how do you work out Rf value?
distance of sample / solvent front
what is the solvent front?
how far you let the water travel up the paper.
what is gas chromatography?
where you seperate a mixture of gases by dissolving them in a mobile phase and making them travel up a tube filled with bits of stuff (the stationary phase). you time how long it takes for the components to travel up the tube.
how does a fractionating column work?
it works as it forces any solution that is not fully a gas (a vapour) to come in contact with the beads and drip back down into the mixture.
