Chemistry S2 Exam Flashcards
What are the 3 states of matter?
solid, liquid, gas
What are all substances made of?
atoms
What are atoms?
small particles that make up matter
What are atoms arranged in?
different solids, liquids and gases
Say 4 things about solids?
-vibrate in a fixed position
-close together
-have a fixed shape
-arranged in a regular pattern
Say 4 things about liquids?
-arranged in a random way
-move around each other
-don’t have a fixed shape
-close together
Say 4 things about gases?
-don’t have a fixed shape
-arranged in a random way
-move quickly in all directions
-far apart from each other
Can a solid be compressed and why?
No. The particles are really close together (not possible to get closer)
Can a liquid be compressed and why?
No. The particles are still very close together
Can a gas be compressed and why?
Yes. There are big spaces between particles that can be ‘squashed’
What is the changing of states in melting?
solid to liquid (ice to water)
What is the changing of states in boiling?
liquid to gas (water to steam)
What is the changing of states in condensing?
gas to liquid (steam to water)
What is the changing of states in freezing?
liquid to solid (water to ice)
What is sublimation?
the process by which solids turn into gases without melting into a liquid first e.g solid to gas
What is water’s melting point, boiling point and its state at room temperature?
melting point: 0°C
boiling point: 100°C
state at 25°C: liquid
What is mercury’s melting point, boiling point and its state at room temperature?
melting point: -39°C
boiling point: 357°C
state at 25°C: liquid
What is iron’s melting point, boiling point and its state at room temperature?
melting point: 1538°C
boiling point: 3000°C
state at 25°C: solid
What is oxygen’s melting point, boiling point and its state at room temperature?
melting point: -218°C
boiling point: -183°C
state at 25°C: gas
What is bromine’s melting point, boiling point and its state at room temperature?
melting point: -7.2°C
boiling point: 59°C
state at 25°C: liquid
Why do gases have a greater volume than liquids?
much more space between gas particles so they take up a greater volume
When you breathe on a cold surface like a window why does it go foggy?
condensation; warm water vapour lands on the colder surface, it condenses back into a liquid
What is viscosity?
measure of how easily a liquid flows (the slower it flows the higher the viscosity)
What is a variable?
something that changes
What is diffusion?
when the particles of a substance move through those of another substance
What happens when objects get hot?
they expand
What happens when objects get cold?
they contract
What happens when a bimetallic strip is heated?
the brass expands more than the iron which causes the strip to bend more towards the iron side
What happens when substances are heated?
their particles move further apart occupying more space or they expand
Why don’t we get squashed by air pressure?
pressure inside us pushes out balancing air pressure that is pushing in
What happens the higher you go in the atmosphere?
there is less air so the air pressure decreases
What does immiscible mean?
liquids not able to be mixed
What happens if something has a density lower than water?
it always floats
What happens if something has a density higher than water?
it sinks
How do you work out density?
Density = mass/volume
What is an element?
a substance made up of only one type of atom
Approximately how many elements are there?
118
How were the elements of the periodic table grouped together?
based on their chemical properties
What does each element have?
a symbol and an atomic number
How can you tell if an element is a conductor or not?
if the light bulb lights up the element is a metal
What is a group in the periodic table?
vertical column (elements in the same group have similar chemical properties)
What are the names of the groups in the periodic table?
-alkali metals
-transition metals
-halogens
-noble gases
When are compound formed?
the atoms of elements join together
What do the vast majority of substances exist as?
compounds
What is the difference between an element and a compound?
-an element is a pure substance that is made from a single type of atom
-a compound is a substance formed when two or more different elements are chemically bonded together
What is meant by the term molecule?
a molecule is a group of atoms joined together
What happens if a compound contains 2 elements?
-ide
What happens if a compound contains 3 elements, one of which is oxygen?
-ite or -ate
How can compounds be broken down into their elements again?
the technique called Electrolysis (meaning splitting compounds using electricity)
In many compounds what do the atoms that join together in groups called?
molecules
How are compounds and mixtures different?
in a mixture that atoms are not joined together
When does a chemical reaction occur?
when elements and compounds change into new substances
What is there always in a chemical reaction?
an energy change sometimes energy is released and other times it is absorbed
What is always made during a chemical reaction?
a new substance/compound
What are reactants?
these are the chemicals present at the start of the chemical reaction
What are products?
these are the new chemicals which are produced in the reaction
What do you never use in a word equation?
never: =
always use an: arrow
What are changes that can occur in a chemical reaction?
-a colour change
-an energy change (sound, heat, light)
-a solid is formed (precipitate)
What is oxygen essential for?
life and combustion
What is the test for oxygen?
relight a glowing splint
What is the test for hydrogen?
burns with a pop
What is the test for carbon dioxide?
turns lime water cloudy
How can you tell if the substance was soluble or not?
if it dissolves in water it is soluble it not it is insoluble
What is a solute?
a solid which dissolves in a solvent to make a solution
What is a solvent?
liquids that dissolves the solute
What is meant by the term Saturated Solution?
a saturated solution is one which can dissolve no more solute into the solvent
What is the calculation of mass of sal contained in 1 litre of seawater?
mass of salt in 20cm3 x 50 = mass of salt in 1 litre of sea water
A substance can only be separated from water by filtration if it is what?
insoluble
What is meant by the term mixture in a chemical sense?
it can be easily separated and the substances in the mixture are not chemically bonded
What can a substance which has dissolved in water be separated by?
evaporation
What is the function of the condenser?
to condense the vapours back into a liquid
What is distillation the method of?
separating 2 or more liquids with different boiling points
What are the changes of states in the distillation process?
in the flask: liquid to gas = evaporation
in the condenser: gas to liquid = condensation
What are all solutions in water either?
-acidic
-alkaline
-neutral
What do indicators do depending on whether they are added to acid, alkaline or neutral solutions?
change colour
Is there just one types o indicator?
no there are many different types
How could you determine whether a solution was acid, alkali or neutral?
red/orange/yellow/pale green = acid
green = neutral
dark green/blue/purple = alkali
What is the type of solution if the colour of the universal indicator is red?
strong acid
What is the type of solution if the colour of the universal indicator is green?
neutral
What is the type of solution if the colour of the universal indicator is turquoise?
weak alkali
What is the type of solution if the colour of the universal indicator is yellow/pale green?
weak acid
What is the type of solution if the colour of the universal indicator is purple?
strong alkali
What does exothermic mean?
heat given off by the reaction
Why do we use evaporation?
to separate a liquid from a solid
Why do we use filtration?
to separate an insoluble solid from a liquid
Why do we use distillation?
to separate liquids based on their boiling points
