Knowledge - states of matter term 1 Flashcards
Describe the cycle of solid -> liquid -> gas
- solid -> liquid: melting
- liquid -> solid: freezing
- liquid -> gas: boiling
- gas -> liquid:
Condensing.
How do you figure out the number of neutrons in an element just from its chemical structure?
Atomic number = number of protons
Mass number = number of protons + neutrons
So, to find number of neutrons we do mass number - atomic number.
What does the ending -ide Mean in the names of compounds?
-ide means the compound contains 2 elements (one is the nonmetal -ve ion)
Depending on the group number how many electrons will an element lose or gain? (1,2,6,7)
- Group 1 metals - lose 1 electron, Form +1 ions.
- Group 2 metals - lose 2 electrons, and form +2 ions.
- group 6 nonmetals - gain 2 electrons, form 2- ions
Group 7 nonmetals - gain 1 electron, form 1- ions.
Describe the relative energy of gas.
Particles have the most energy - as the particles are the most spread apart.
Describe the relative energy of liquids.
Particles have more energy than those in a solid, but less than those in a gas.
Describe the relative energy of solids.
Solid has the least energy - particles are fixed.
What are state changes?
state changes (melting, boiling, freezing and condensing) are physical changes - they involve the forces between the particles of the substances but the particles themselves don’t change.
What are chemical changes?
Chemical changes are where a new product has been formed.
Explain the changes in arrangement, movement, and energy of particles during changes of state.
*Particle theory can help to explain melting, boiling, freezing and condensing..
* The amount of energy needed to change state from solid to liquid and from liquid to gas depends on the strength of the forces between the particles of the substance.
* The nature of the particles involved depends on the type of bonding and the structure of the substance.
* The stronger the forces between the particles the higher the melting point and boiling point of the substance.
What does the melting/boiling point mean for the physical state of a substance.
- At temperatures below the melting point, the substance will be solid.
- At temperatures above the melting point but below the boiling point, the substance will be liquid.
- At temperatures above the boiling point, the substance will be a gas
In everyday language, describe a pure substance.
A substance that has had nothing added to it, so it is unadulterated and in its natural state, e.g. pure milk.
Describe simple distillation?
- used to separate a pure liquid from a mixture of liquids
- works when the liquids have different boiling points
- commonly used to separate ethanol from water
- (using ethanol as an example) ethanol has a lower bp than water so it evaporates first. The ethanol vapour is then cooled and condensed inside the condenser to form a pure liquid.
- Sequence of events in distillation is as follows: hearing -> evaporating -> cooling -> condensing.
Describe fractional distillation.
- The oil is heated in the fractionating column and the oil evaporates and condenses at a number of different temperatures.
- The many hydrocarbons in crude oil can be separated into fractions each of which contains molecules with a similar number of carbon atoms.
- The fractionating column works continuously, heated crude oil is piped in at the bottom. The vaporised oil rises up the column and the various fractions are constantly tapped off at the different levels where they condense.
- The fractions can be processed to produce fuels and feedstock for the petrochemical industry.
Describe filtration.
- If you have produced e.g. a precipitate (which is an insoluble salt), you would want to separate the salt/precipitate from the salt solution.
- you would do this by filtering the solution, leaving behind the precipitate on the filter paper.
