Matter
Why do we have to balance equations?
Because we can't create matter/ law of conservation of mass.
What is the difference between mass and weight?
Mass is the amount of matter that makes up an object. It doesn't change depending on the gravity of the planet it is on. Whereas weight is the force of gravity impacting an object so people can bounce higher on the moon due to having less weight there but not less mass.
Why is the Periodic Table important in chemistry?
Many various reasons are acceptable.
The reactants are written on the left hand side or right hand side of the arrow in a reaction?
The left hand side
On which axis do you usually plot the dependent variable?
y-axis
Name the states of matter and give an example from the periodic table of different elements that have this state.
Solids - any metal, some non-metals
Liquids - mercury or bromine
Gas - any noble gas and some non-metals
How does increasing the density of gases (pressure) impact on reaction rate?
It makes more collisions happen faster.
What is it called when an atom loses an electron and becomes negative? (cation or anion)
anion
Define what a combustion reaction is and give an example.
Respiration
Burning of wood.
Define: reliability, validity and accuracy.
Reliability - how close the results are to one another.
Validity - whether you controlled variables well and therefore measured what you intended to measure.
Accuracy - how closely your results match to the well known/ accepted value.
Define precipitation of a solution.
When two aqueous liquids react to make a solid.
What is the density formula?
d=m/v
Sodium chloride
Potassium bromide
Calcium sulfide
The metal is always named first.
Give the general equation of the combustion reaction.
What is one advantage of line graphs compared to column graphs when plotting data like time, a continuous variable?
It allows you to make predictions between time poitns. E.g. if you took measurements every day you could predict what the value would be every half a day.
An atom is one type of element e.g. iron whereas a compound is two different elements bound together e.g. carbon dioxide.
The density decreases as the particles move more and have more space between them and therefore increase the volume for the same mass.
How many valence electrons (or what charge) do most metals have when reacting? +1, +2 or +3?
+2 because they lose two electrons
Give the general equation for a metal carbonate + acid reaction.
Metal carbonate + acid -> salt + CO2 + H2O
What does it mean that there is a "law" of the conservation of mass? I.e. what is the law part of that sentence mean?
It means there is a mathematical relationship defining how mass is always conserved in a reaction.
Give an example of a compound with different properties to the elements that make it up.
Salt (sodium chloride) is very different to sodium (an explosive metal) and chlorine (a green toxic gas)
Why is it incorrect to say that heavy things sink in water?
Because a ship is heavy and yet it floats. It is not to do with heaviness but density.
What does the group (vertical) of the Periodic Table have to do with the reactivity?
It determines the valency and therefore how reactive (more likely to steal/ donate an atom) an element is.
Give the general equation for a metal + acid reaction.
Metal + acid -> salt + H2
Because you could obtain different results. Repeating allows you to judge reliability.