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An atom has 13 protons and 14 neutrons. What is its mass number?
27
What are isotopes?
atoms of the same element (with the same number of protons) but with a different number of neutrons
What is a compound?
a substance made up of 2 or more elements that are chemically combined (in fixed proportions)
What does endothermic mean?
absorbs heat from the surroundings
What does exothermic mean?
releases heat into surroundings
What happens to solids when they are heated?
they expand (the hotter a solid gets, the faster its particles vibrate. This means that solids expand when they're heated)
What is a molecule?
2 or more atoms bonded together
What is an element?
a substance that contains only ONE type of atom
Where are protons found?
nucleus of an atom
Where are neutrons found?
nucleus of an atom
Where are electrons found?
in shells surrounding the nucleus
What does the atomic number tell you?
the number of protons in the nucleus of an atom
What does the mass number tell you?
total number of protons and neutrons / total number of subatomic particles in the nucleus of an atom
How do you work out the number of neutrons?
mass number - atomic number
How are substances separated in paper chromatography?
The substance's attraction to the mobile phase only, each substance has a different attraction to each phase so travels up the paper by a different amount, allowing the mixture to be separated.
What property of the sand allows it to be removed from the water by filtration?
sand is an insoluble solid
What is an atom made up of?
subatomic particles; neutrons, protons and electrons
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
What is the relative mass of a electron?
1/2000
What is the relative charge of a electron?
-1 (negative electric charge)
What is the relative charge of a proton?
+1 (positive electric charge)
What is the relative charge of a neutron?
0 (no electric charge)
How much electric charge does an atom have?
atoms are neutral, meaning they have a total of zero electric charge
What does the number of protons and electrons in an atom have in common?
atoms contain the same amount of protons and electrons (to maintain the atom/zero charge)
What do you call an atom that has lost electrons?
a positive ion
What do you call an atom that has gained electrons?
a negative ion
How are elements in the periodic table organised?
in order of increasing atomic number (from left to right) and their properties
What do elements in a group have in common (atom-wise)?
they have the same number of electrons in the outer/last shell
What do elements in a period have in common (atom-wise)?
they have the same number of shells around their atom
Is a group a horizontal or vertical line on the periodic table?
vertical
Is a period a horizontal or vertical line on the periodic table?
horizontal
What are the four separation techniques?
filtration, evaporation, distillation, crystalisation
What is a pure substance?
a substance made up of only one type of element or one type of compound
Can you use separation techniques with a pure substance?
no, a pure substance can't be separated into anything simpler without a chemical reaction
What is a mixture?
a combination of two or more substances that are not chemically combined (e.g. sea water and air)
Can you use separation techniques with a mixture?
yes, a mixture can be separated using physical methods because the substances aren't chemically joined
What is a solute?
the substance being dissolved
What is a solvent?
the substance in which the solute dissolves
What is a solution?
a mixture of a solute and a solvent (that does not separate out)
What does soluble mean?
it will dissolve
What does insoluble mean?
it won't dissolve
What is solubility?
the measure of how much solute will dissolve in a solvent
What does filtration do?
separates insoluble solids from liquids (mixtures)
What equipment is needed for filtration? (3)
funnel
filter paper
beaker
What does evaporation do?
separates a soluble solid from a liquid
What equipment is needed for evaporation? (3)
bunsen burner
evaporating dish/crucible
tripod
What are the steps of evaporation? (2 steps)
Place solution in an evaporating dish/crucible and place it on a tripod.
Slowly heat it with a bunsen burner.
Why do crystals form during evaporation?
Because as the solvent (liquid) begins to evaporate, the remaining solution will become more concentrated. When the solution becomes so concentrated, crystals will begin to form.
What is thermal decomposition?
the breaking down of a substance by heating
What does crystallisation do?
separates a soluble solid, which is vulnerable to thermal decomposition, from a solution.
What equipment is needed for crystallisation? (6)
evaporating dish/crucible
water bath (or any gentle heating mechanism)
tripod
funnel
filter paper
source of heat (e.g. over or sun)
What are the steps of crystallisation? (5 steps)
Place solution into an evaporating dish/ crucible.
Very gently heat the solution (e.g. using a water bath).
Once some of the solvent has evaporated and you can start to see crystals forming, stop heating and leave it to cool.
Filter out the crystals from the remaining solution, using filtration.
Dry crystals, using heat (e.g. oven or somewhere warm)
What does (simple) distillation do?
separates a solute and solvent or a solvent from solvent, but keeps the solvents.
What equipment do you need for simple distillation? (7)
flask
bunsen burner
bung
thermometer
condenser
water jacket
beaker
What happens during distillation?
A liquid is boiled to produce steam which rises to the top of the flask, forcing it down the condenser where the liquid condenses back to a liquid (because of the continuously flowing cold water in the water jacket). The liquid will then run down the pipe into a beaker.
What is the conservation of mass?
atoms cannot be made or destroyed
What is chromatography?
a separation technique and/or a method to identify substances in a mixture
Who made the first accepted periodic table and when?
Dmitri Mendeleev, in 1869
What two things did Dmitri Mendeleev do differently with his periodic table?
left gaps for elements he predicted had yet to be discovered
was prepared to alter slightly the order of the elements
What are miscible liquids?
liquids that mix
What are immiscible liquids?
liquids that do not mix completely, but separate into layers due to differences in densities
What is an example of when you would use filtration?
to separate sand from water
What is an example of when you would use evaporation?
to separate salt from water
What is an example of when you would use crystallisation?
to separate copper sulphate crystals from a solution of copper sulphate
What is an example of when you would use simple distillation?
to separate pure water from sea water
What is the Rf calculation? (chromatography)
Rf = distance travelled by substance / distance travelled by solvent
If red ink travelled 3cm up filter paper, and the water travelled 4cm up the filter paper. What is the Rf value?
0.75cm
What are the alkali metals?
Group 1 : Lithium, Sodium, Potassium, Rubidium, Cesium, Francium
What are 3 properties of the alkali metals?
soft, it is easy to cut them
appear to be dull, because they react with the oxygen in the air
react with water to make an alkali
How many electrons are in the outer shell of the alkali metals (group 1)?
one electron in their outer shell
How many electrons are in the outer shell of the noble gases (group 0)?
eight electrons in their outer shell (full outer shell)
Why is group 1 so reactive, but group 0 is unreactive?
Because the atoms in group 1 want to get rid of the electron on their outer shell desperately to become stable. This means they react with more atoms/elements in order to get rid of the electron on their outer shell. Whereas group 0's atoms are stable and do not want to lose any electrons.
What is an atom's main goal?
to have a full outer shell
When you go down group 1 (Alkali metals) does the reactivity increase, decrease or stay the same?
increase
When you go down group 7 (Halogens) does the reactivity increase, decrease or stay the same?
decrease
When you go down group 0 (Noble gases) does the reactivity increase, decrease or stay the same?
stay the same
When you go down group 7 (Halogens) do the melting and boiling points increase, decrease or stay the same?
increase
When you go down group 1 (Alkali metals) do the melting and boiling points increase, decrease or stay the same?
decrease
When you go down group 0 (Noble gases) do the melting and boiling points increase, decrease or stay the same?
increase
What is the second version of the atom that was made?
JJ Thompson's 'plum pudding' atom
What is the third version of the atom that was made?
Rutherford's atom
What was the alpha particle experiment (simply) and what was it's outcome?
Alpha particles were fired at gold foil (atoms). Some went straight through, some deflected and 1 in 50,000 bounced back.
What was the prediction of the alpha particle experiment?
the Alpha particles would go straight through the gold foil (atoms) - they could push through and not be affected by the positive ball of mass (Dalton's atom)
they would not be stopped by electrons
A gas is tested with a burning splint and produces a squeaky pop. What gas is it?
hydrogen
How can you tell from a chromatogram how many substances were present in the mixture?
from the number of spots made from the original mixture is the number of different substances in the mixture
Which gas causes damp blue litmus paper to turn white?
chlorine
What were Rutherford's two overall discoveries from the alpha particle experiment?
the atom is mostly empty
the nucleus and that its positively charged
What are the elements in between the groups called on the periodic table? (e.g. Au - gold)
Transition Metals
What does (aq) mean?
aqueous (dissolved in water)
What is an atom?
building block of the universe
As you go down a group are the outer electrons nearer or further from the nucleus?
further
As you go down a group is the attraction between the nucleus and the outer electrons getting stronger or weaker?
weaker
What are the properties of the plum pudding model?
neutral
solid ball of positive charge
negatively charged electrons stuffed in it
Describe what happens when an alkali metal is put into water?
they produce heat (flame), hydrogen gas (the fizz and gas created), the corresponding metal hydroxide and they turn the water into an alkali solution
How did Mendleev organize his periodic table?
by increasing atomic mass and properties
What is the stationary phase in chromatography?
phase in chromatography that does not move/non-moving phase (the fixed point where you make measurements from/pencil line)
What is the mobile phase in chromatography?
phase in chromatography that moves (the solvent that moves through the paper, carrying different substances with it_
What is a formulation?
a mixture that has been designed to do something useful, that has required properties
If a substance is impure the melting point will be __________ and the substance will melt over a broad range of temperatures.
lower
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