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AQA Chemistry (double)
Fichas del conjunto (69)
- 1Structure of an atom
- 2The relative charge and mass
- 3Atomic Theory-All matter is made of atoms
-atoms can't be broken into anything simpler
-each atom in a specific element are identical but different from atoms in other elements
-rearranged into chemical equations
- compound formed of 2 or more atoms - 4Isotopes-atoms of an element with the normal number of protons and electrons, but different numbers of neutrons. Isotopes have the same atomic number, but different mass numbers.
- 5Electronic structureThe electronic structure of an atom is a description of how the electrons are arranged. It can be shown as numbers or as a diagram.
- 6Atomic number and mass numberatomic number- The number of protons in each atom of an element
mass number-number of protons and newtons in the nucleus is the mass number
- 7periodic table development- He arranged the known elements in order of their atomic masses. He proposed a 'law of octaves', meaning every eighth element had similar properties. He put the known elements in order of relative atomic mass but left gaps for undiscovered elements.
- 8Group 1- alkali metals-very reactive so stored in oil
-very low density
- burn on water
-soft
-low melting points - 9Group 7- halogens- non-metals colours vapours
-low melting and boiling points - 10Fullerenes and nonotubes-The fullerenes are a large class of allotropes of carbon and are made of balls, ‘cages’ or tubes of carbon atoms.
-Nanotubes are fullerenes that can be used to reinforce.. They are also used as semiconductors in electrical circuits
- 11Do simple molecule substances conduct electricity-Even in room temp they don't because there is no overall charge
- 12States of Matter
- 13Solids-have a fixed shape and volume
-cannot be compressed - 14Liquids-Have a fixed volume
-can flow and change shape
-occupy more space (water and ice exceptions) - 15Gases- no fixed shape/volume
-compressed eaisily
-particles spread and ease of movement in random directions - 16What can change the speed of particles?-Heat (increases)
- 17Changing States
- 18Energy transfers during change of state
- 19What is a chemical compound?2 or more elements mixed together that have chemically combined.
They can not be gained back easily - 20What is a mixture?2 or more elements mixed together that have not chemically bonded
- 21Making elements stableWhen an element is in group 8 or 0 they have full electrons on their outer shell making them stable however is they are not they will either share electrons (covalent bonding) or transferring electrons (ionic bonding)
- 22What do groups mean?How many electrons on the outer shell
- 23What to periods mean?How many shell the element has
- 24When does a element lose electrons?-When they are in group 1,2 or 3
eg sodium (2,8,1) will lose one to make it (2,8) no it is a positively charged ion. - 25Sodium loss of electron diagram
- 26When does an element gain an electron?-When it's in groups 5, 6 and 7
eg what sodium reacts with chlorine (2,7) needs one electron to be stable so it takes one of sodium to become (2,8) and therefore becomes negatively charged - 27Chlorine gain of electrons diagram
- 28Ionic Bonding-normally form when non-metals react with metals.
-metals form positive ions and non-metals for negative ions - 29more on ionic bonding-ions formed held by strong forces of attraction of oppositely charged ions.
-The electrostatic attraction in will direction. This results in giant structures or giant lattice. - 30ionic bonding diagram
- 31Giant ionic structures- takes lot of effort to break due to the electrostatic forces attracting in all directions
- 32What happens when u provide enough energy to separate them?-become mobile ( free to move ) when becomes liquid
-they are attracted to oppositely charged electrodes so they carry electrical charge through liquid. - 33Why can't solid ionic compounds conduct electricity?- as in a solid the ions are in a fixed place
- 34Diagram of electricity travelling through liquid-Ionic compounds will dissolve in water and the lattice is split up up by water molcules allownig the ions to move freely
- 35—
- 36Covalent Bonding-When non-metals react, their atoms shape pairs of electrons to form molecules.
- 37Simple molecules-non-metals normally gain electrons
- so 2 non-metals can't give electrons so instead they share electrons
-the strong bonds holing them are called covalent bonds - 38Example Diagram
- 39These can involve multiple elements if needed more electrons
- 40Giant Covalent structures-Consist of small molecules
-Some substances have giant structures due to large amounts of electrons so they are held my a network of covalent bonds - 412D, 3D ball and stick models2D-show which atoms are bonded to each other but not the true shape of molecule
3D-Tries to show the shape but is hard to understand
- 42Inter molecular forces-As covalent bonds are strong the molecules are tightly packed
-molecules are pretty separate so are held by intermolecular forces (easily breakable) - 43Metallic Bonding-Electrons in the outer shell are (decolonised) free to move around
-electrostatic attraction between positive metal ions shared with negative
-very strong
-carry electrical and thermal current
- 44Giant Metallic structures- layers of atoms. Atoms are identical so electrons easily slide of each other (malleable)
-alloy mixture 2 + metals/ pure metal too soft. Elements have different sized electrons so when they are mixed they won't slide making them stronger
- 45Relative formula mass-Relative atomic masses can be used to find the relative formula mass of a compound.
- 46Moles- the unit for amount of substance.. To find the relative formula mass (or Mr) of a substance, you add together the relative atomic mass for all the atoms shown in its chemical formula.
- 47balanced equations- both sides of equation must me the same (reactants → products)
- 48concentration in solutionsconcentration= moles / volume
- 49The reactivity seriesIn a reactivity series, the most reactive element is placed at the top and the least reactive element at the bottom. More reactive metals have a greater tendency to lose electrons and form positive ions.
- 50displacement reactions-A more reactive metal will displace a less reactive metal from a compound.Because aluminium is more reactive than iron, it displaces iron from iron(III) oxide. The aluminium removes oxygen from the iron(III) oxide:
- 51Methods of extracting metals-metals can be found as ores (a rock containing a metal)
- 52acids and basesacid + metal oxide → salt + water
acid + metal hydroxide → salt + water - 53Reactive metals Acids will react with reactive metals, such as magnesium and zinc, to make a salt and hydrogen:acid + metal → salt + hydrogen
- 54The Ph scale -to tell if a solution is acidic or alkaline use an indicator -Litmus (indicator using colour) can be used as a liquid, or as litmus paper.
- 55Strong and weak acids-Acid solutions contain hydrogen ions. The higher the concentration of hydrogen ions, the lower the pH.
-Strong acids are fully ionised but weak acids are only partly ionised in solution.
-The electrolysis of acids produces hydrogen gas at the negative electrode.
- 56ElectrolysisElectrolysis - the decomposition of a liquid using electricity
Electrolyte - a liquid which conducts electricity
Anode - the positive electrode
Cathode - the negative electrode
Anions - negative ions - attracted to the anode
Cations - positive ions - attracted to the cathode
- 57Electrolysis of molten compounds-ions must be free to move for electrolysis to work.
-They are free to move in aqueous solutions and in molten liquids.
-fixed positions in solid ionic compounds they cannot move does not work in solids.
- 58Molten compounds in a equation
- 59Electrolysis of aqueous solutions
- 60aqueous solutions in equation
- 61Extraction of aluminium by electrolysis -Aluminium ore is called bauxite. The bauxite is purified to yield a white powder -expensive because lots of electricity used up in the extractionfirst the aluminium oxide must be made molten so that electricity can pass through it so it is dissolved in molten cryolite. cryolite reduces energy costs involved in extracting aluminium.
- 62Both the negative electrode (cathode) and positive electrode (anode) are made of graphite, a form of carbon.Aluminium metal forms at the negative electrode and sinks to the bottom of the tank, where it is tapped off
.Oxygen forms at the positive electrodes. This oxygen reacts with the carbon of the positive electrodes, forming carbon dioxide and will burn away.
- 63Exothermic reactions- heat exits into surroundings eg combustion , neutralization-energy change is negative
-REACTANTS → products
more energy in reactants as energy is lost through heat
- 64Endothermic reactions- heat enters from surroundings-Energy change is positive
reactants → PRODUCTS
more energy in products as energy (heat) from surroundings is being absorbed
- 65—
- 66(Ea) ACTIVATION ENERGYis the MINIMUM amount of ENERGY NEEDED for a chemical reaction to take place
- 67Bond breaking- Energy is absorbed to break bonds. Bond-breaking is an endothermic process.Energy absorbed is more than the energy release
- 68Bond making- Energy is released when new bonds form. Bond-making is an exothermic process.Energy released is more than the energy absorbed
- 69Calculating Energy Transfers
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- GCSE Chemistry Fichas sobre AQA Chemistry (double), creado por Nicola Kwiatkowska el 11/06/2018.
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- Nicola Kwiatkowska
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