Principles of chemistry Flashcards
Properties of a solid?
forces between particles, particle positioning, type of shape, movement
Strong forces of attraction between particles
Fixed positions in lattice arrangement
Keep definite shape and volume
vibrate about positions
Properties of liquids?
forces between particles, type of shape, movement
Weak forces of attraction between particles
Don’t keep a definite shape, but do keep a definite volume
Moving with random motion
Properties of gasses?
forces between particles, type of shape, movement
Forces of attraction between particles are very weak
Don’t have definite shape or volume
Moving constantly with random motion
What’s going from a solid to a gas called?
Subliming
How do states change from to another?
Gain energy, so they vibrate more and break or weaken the bonds
What’s diffusion?
The gradual movement of particles from an area of high concentration to low
What can you use to show diffusion?
Potassium manganite in water, bright purple spreads out
How can ammonia and hydrogen chloride show diffusion?
Put at 2 sides of a tube, white ring will form where they meet, closer to hydrogen chloride, because ammonia diffuses faster
What happens when bromine gas (brown) mixes with air in a tube?
Bromine diffuses making the air browner
Features of a nucleus?
location, what it contains, what charge, mass
Middle of atom
Contains protons and neutrons
Positive charge due to protons
Small compared to rest of atom, but contains all mass
Features of electrons?
Move around the nucleus in shells
negatively charged (-1)
Very small
No mass
Features of protons?
Relative mass=1
Relative charge = 1
The number of protons equals?
The number of electrons
Features of a neutron?
Relative mass=1
No charge
What’s the mass number?
Total number of protons and neutrons
What’s the atomic number?
Number of protons
How do you find the amount of neutrons?
Mass number subtract atomic number
What are molecules?
Groups of atoms held together by covalent bonds
Elements consist of?
1 type of atom
What’s a diatomic molecule?
A molecule with 2 atoms
What’s a compound?
2 or more different elements chemically bonded together
What’s a mixture?
When there’s no chemical bond between parts, and they can be separated by physical methods
What’s filtration used for?
To separate an insoluble solid from a liquid (filter paper)
What’s crystallisation used for?
Separating a soluble solid from a soloution
Method for crystallisation?
Pour solution into evaporating dish
Heat solution
Place in warm place to allow evaporation from the crystals
Dry in drying oven
How can you use filtration and crystallisation to separate rock(Insouluble)Salt(solouble)?
Grind up
dissolve in beaker
Filter
Crystallise
What’s paper chromatography?
Putting dots of ink on a piece paper, placing it in a solvent and seeing how soluble the dyes are by how far they move up the paper
What’s simple distillation used for?
Separate solutions
What’s fractional distillation used for?
Separating a mixture of liquids, different boiling point come out at different fractions
What are groups on the periodic table?
Amount of outer electrons
What are group 1 elements called?
alkali metals
What are group 7 elements called?
halogens
What are group 0 elements called?
Noble gases
What are the electron shell rule?
they fill up shells in the form 2:8:8
Happiest when they have a full shell
Want to react when it’s not full
What’s ionic bonding?
When atoms bond and lose or gain electrons to become strongly attracted to each other through electrostatic attraction
What’s oxidation?
When an atom loses electrons
What’s reduction?
When an atom gains electrons
What are positive ions called?
Cations
What are negatively charged ions called?
Anions
When does ionic bonding occur?
When an atom wants to get rid of electrons, and another atom wants to gain an electrons
Why do giant ionic structures have high melting and boiling points?
closely packed 3D lattice arrangement,
oppositely charged ions mean strong forces if attraction
What’s covalent bonding?
When atoms share electrons to fill each others outer shell
What are the atoms within a molecule bonded by?
Strong covalent bonds
What are the forces between molecules like?
Very weak
Features of giant covalent structures?
type of bonds, melting point, do they conduct, are they soluble
Bonded by strong covalent bonds
Lots of bonds so high boiling/melting point
Don’t conduct electricity
insoluble in water
Features of diamond?
Each carbon atom has 4 covalent bonds
very hard
Features of Graphite?
Each carbon atom only makes 3 bonds, creating layers which can slide over each other making it a good lubricant
this leaves free electrons so it’s the only non metal which can conduct electricity
What does aqueous mean?
Dissolved in water
What does a balanced equation require?
Even amount of atoms on each side of the equation
What’s an isotope?
Different atomic forms of the same element, which have the same number of protons but different amount of neutrons
How to find the average mass of an isotope, when given 2 relative masses and 2 relative abundances?
(relative abundance 1 x mass 1) + (Relative mass 2 x mass2) /(relative abudance 1 + relative abundance 2)= average mass
How to find the relative mass?
Add up the masses from all the atoms in the subject
How to find the empirical formula?
1) write all elements
2) Write the experimental masses or percentages
3) Divide each mass by their RFM
4) turn these numbers into a ratio
5) Write out the formula
How to find the molecular formula?
1) Work out the mass of the empirical formula of the elements you’ve been given
2) See how that compares to the RFM of the full molecule
3) divide or multiply the elements to get the mlecularformula
How to find masses in reactions?
1) Work out the RFM of the 2 things which create each other
2) Multiply and divide the masses until you get the ratio which allows you to answer the question
What’s the actual yield?
The actual amount of product you get when doing the experiment
What’s the theoretical yield?
The yield you get when you work out masses you a balanced symbol equation
What’s the percentage yield?
The actual yield compared to the theoretical yield
Formula for percentage yield?
Percentage yield= actual yield (grams) / theoretical yield (grams). then x answer by 100
What’s a mole
The number (6.023 x 10 to the power of 23), making an elements mass in grams equal to its RFM
How do you find moles when given RFM and mass?
Moles = mass in g / RFM
What do salts consist of?
Lattice arrangement of positive and negative ions
A solid salt containing water of crystallisation is?
Hydrated
A solid salt containing no water of crystallisation is?
Anhydrous
How to calculate how much water of crystallisation a salt contains?
Work out the mass of the anhydrous salt with and without water
Calculate the moles of water lost
Calculate the moles of anhydrous salt made (using the mass and rfm)
Find the ratio of moles of anhydrous salt to water (using the mass and rfm)
Put these ratios in the Formula for the hydrated salt
What’s Avodaros law?
One of mole of any gas occupies 24dm(cubed) at room temperature and pressure
How to find the moles of a gas?
Moles of gas= Volume dm(cubed) / 24
How to find the volume of a gas if given the mass of the gas?
Volume (dm cubed) = (mass of gas / RFM of gas) x 24
How to calculate volumes of gases in reactions if you know the masses?
Write balanced equation
Write down the RFM for each part
Divide and multiply to get the mass the question wants
Put the new information into the formula Volume (dm cubed) = (mass of gas / RFM of gas) x 24, to find the required element
What’s concentration?
The amount of stuff per unit volume
Equation for concentration?
Concentration (mol/dm3)= moles/volume
What’s an ion?
A positively or negatively charged atom
What’s an electric current?
A flow of electrons or ions
What state can ionic compounds conduct electricity?
Molten or in a solution
Why can’t solid ionic compounds conduct electricity?
Ions aren’t free to move around
Why can an ionic compound conduct electricity when In a solution or molten?
when dissolved the ions separate, and are free to move in the soloution, so they can carry a current and conduct electricity
Why don’t covalent compounds conduct electricity?
Don’t contain ions, so no charge carriers
Structure of metal?
Lots of positive metal ions, surrounded by a sea of delocalised electrons
What’s metallic bonding?
The attraction between the positive ions and the sea of electrons, giving metals their properties
Why are metals good conductors of heat and electricity
Free electrons carry them effectively
Why are most metals malleable?
Layers in the atom can roll over each other, do they can be rolled into flat sheets
What’s electrolysis?
Passing an electric current through a molten or in solution ionic substance, to make new substances
What’s the liquid required to conduct the electricity in electrolysis called?
The electrolyte
How are electrolytes made?
Dissolving or melting a substance, so it has free ions to conduct electricity
What’s the positive electrode called?
The anode
What’s the negative electrode called?
The cathode
What’s required for the electrolysis circuit to be complete?
A flow of electrons, electrons taken away from ions at the anode, and electrons given to other ions at the cathode
What happens to ions as they gain or lose electrons?
Become atoms or molecules
How to test whether a liquid is a electrolyte?
Use a conductivity probe to see if it produces a current
How are electrolytes made?
By dissolving or melting a ionic compounds so they have free electrons
What does there have to be in electrolysis for the circuit to be complete?
A flow of electrons
What’s the positive electrode called?
The anode
What happens at the anode?
electrons are taken away from the ions
What’s the negative electrode called?
The cathode
What happens at the cathode?
Electrons given to ions
What happens in the electrolysis molten lead bromine?
Lead cations go to cathode and gain 2 electrons and the molten lead then sinks to bottom
Bromine anions go to anode to make bromine, bromine gas goes to the top
Why don’t the electrodes react?
They are inert
why’s electrolysis different in a aqueous solution?
There will be hydrogen ions (H+), and hydroxide ions (OH-)
In an aqueous solution, what happens if H+ ions and metal ions are present?
At the cathode if the metal ions are more reactive that H+ ions then Hydrogen gas will be made. If their not then the pure metal will be produced then
At the anode, if OH- and halide ions (Cl-, Br-, I-) are present there halides molecules will be formed. If there are no halides oxygen will be made
In an aqueous solution, what’s produced in the electrolysis of Sulphuric acid?
Cathode: Hydrogen gas
Anode: Oxygen and water
In an aqueous solution, what’s produced in the electrolysis of Sodium chloride?
Cathode: Hydrogen gas
Anode: Chlorine gas
In an aqueous solution, what’s produced in the electrolysis of copper Sulphate
Cathode: Copper metal
Anode: Oxygen and water
What does the amount of product made by electrolysis rely on?
The amount of electrons transferred
How to increase the amount of electrons transferred?
Longer electrolysis
Increase the current
Equation for charge?
Charge= amps x time
What’s one faraday?
96,000 coulombs, and one mole of electrons
How do you know how many moles of electrons an ion needs to make an atom?
The same amount as the ions charge
How to work out masses from electrolysis?
Write out balanced equation of lead
Calculate the number of faradays
Calculate the number of moles of product made ( Divide the amount of faradays by the amount of electrons)
Work out the RFM to be able to use the moles equation to find the mass
