stuff i didnt know Flashcards
1
Q
what is the diameter of an atom
A
0.1 nm
2
Q
are chemical and physical properties same or different in isotopes. why?
A
- chemical properties are same as same number of electrons
- physical properties are different as have different mass number eg. mp and bp,density
3
Q
how do you calculate relative atomic mass
A
(isotope abundance x mass number) + …… divided by sum of isotope abundance
4
Q
what are mm, nm, micrometers conversions
A
mm is x10-3
micrometers is x10-6
nanometers is x10 -9
5
Q
what is the formula for
nitric acid
sulfuric acid
carbon monoxide
sodium chloride
A
- HNO3
- H2SO4
- CO
- NaCl
6
Q
what happens during covalent bonding
A
share a pair of electrons
7
Q
what happens during ionic bonding
A
metals give electrons to non metals
metals become positive ions
non metals become negative ions
8
Q
what is the ion formula for
- sulfate
- nitrate
- hydroxide
- carbonate
A
- SO4 2-
- NO3 1-
- OH 1-
- CO3 2-
9
Q
what order were the particles and nucleaus discovered
A
- electrons
- nucleus
- protons
- neutrons
10
Q
explain the history of the atom in order
A
- john dalton- atoms are solid
- jj thompson- ball of positive charge with negative electrons embedded randomly throughout- plum pudding model
- rutherford- alpha particle scattering experiment, fired alpha particles at sheet of gold, expecting particles to pass straight through, most did but some defelcted backwards
- conluded that tiny positive nucleus in centre, most mass concentarted in the middle, most atom is empty space - bohr- suggested all electrons were in shells, orbit nucleus in fixed shells in a fixed distance from nucleus
- chadwick- experiments for nuetron particles in nucleus, these resulted in a model of the atom close to modern model the nuclear model
11
Q
explain the development of the periodic table in order
A
- Dalton- elemnets arranged in order of atomic weight, used random symbols nothing to do with element, not all elements
- Newlands- order of atomic weight, arranged elemnets into columns according to pattern. found every 8th element was similar(law of octaves). put metals and non metals in the same group
- Mendeleev- arranged atomic weight, elemnets with simlar properties in same groups, left gaps for undiscovered elements, predicted properties of missing elements which were later found to be correct
- Modern- order of atomic number, elements with similat properties in groups, metals on left, non metals on right, over 100 elements
12
Q
what are the chemical properties of alkali metals
A
- catalysts
- make coloured compounds
- make multiple ions (fe 3+, fe 2+)
13
Q
why are alkali metals called this
A
make alkaline solution in water
14
Q
what are the physical properties of alkali metals
A
down group=
- increase in reactivity
- lower mp and bp
- soft, low density
- formed coloured compounds
15
Q
how do alklai metals react with water? halogens? oxygen?
A
metal+ water–> metal hydroxide + hydrogen
metal + chlorine–> sodium chloride
metal + oxygen—> sodium oxide
16
Q
what are the colurs and states of group 7
A
flourine- yellow gas
chlorine- green gas
bromine- red,bown liquid
iodine- dark, grey solid, purple vapour
17
Q
what are the properties of group 7
A
- decrease in reactivity
- increase in mp and bp as atoms in molecules are bigger so has bigger imfs between molecules
18
Q
what are the properties of rgoup 0 elements
A
- stable,inert-full outer shells
- colourless gases, nonflammable
- Bp and mp increase as bigger atoms, bigger imfs
19
Q
explain ionic compounds
A
- a giant ionic lattice
- regualt lattice with very strong electrostatic forces of attraction as its + and - ions alternating
- high me and bp as lost of energy needed to seperate strong bonds
- solids-cant conduct electricty as ions cant move and carry charge through structure
- can conduct by heating or melting so free to move and carry charge
20
Q
what is the empirical formula
A
simplest whole number ratio of atoms in compound
21
Q
explain simple molecular substances- use covalent bonding
A
- low mp and bp as have weak imfs that need to be broken NOT COVALENT BONDS so molecules are easily separated, little energy needed
- most gas or liquid at room temp
- mp and bp increase as molecules get bigger
- dont conduct electricty as not charges so no free electrons or ions which can move and carry charge
22
Q
giev 3 exmapless of giant covalent structures
A
- diamond
- graphite
- silicoln dioxide
23
Q
explain graphite as a giant covalent structure
A
- high mp and bp as covalent bonds take lots of energy to break
- layers of hexagons with 3 covalent bonds between carbon atoms
- electron is delocalised so can carry charge
- good lubricants as weak imfs between layers so they can slide
24
Q
exaplin diamond as a giant covalent sturcture
A
- 4 very strong covalent bonds between carbon atoms
- very high mp and bp as covalent bonds take lots of energy
- very hard/strong
- no conduction of electricty as no delocalised electrons
25
explain sislcoln dioxide as a giant covalent structure
- high mp and bp as covalent bonds take lots of energy to break
- sand
- 4 covalent bonds
- no conduction of electricty
26
explain graphene as an allotrope of carbon
single layer of graaphite
conducts electricty as delocalised electron
very strong/light
27
explain fullerens as allotropes of carbon
- eg buckmisnsterfullerene- sphere C60, good lubricant, cage medicine to deliver drug into body, massive sa:v so great catalysts
28
explain nanotubes as allotropes of carbon
- conduct electricty and heat, high tensile(stretch) strength
29
what happens in metallic bonding
theres strong attraction between postive metal ions and negative delcoalised electrons
- positive metal atoms are in regular arragemnt with electrons through it
30
explain the different nano particles and the uses
nano is 1x10 -9 to 1x10 -7 m
fine particles is 1 x10-7 to 2.5 x10 -6 m
coarse particles is 2.5x10-6 to 1x10 -5
- massive sa:v so use less of it for the same effects eg catalyst. nanomedicine as absorb more easily into body, some conduct electricty, silver nanoparticles are antibacterial, sun cream
- effects on body not yet fully known may damage cells
31
comaper difference ingroup1 physical properties with transition metals
- g1 is softer
- g1 have lower mp and bpp
- transiton are denser, stronger
32
explain why aluiuim is more expensive than carbon
- more energy needed to obtain as uses electrolysis
33
explain why the conductivity og the mixture was 0 when acid had just been neutralsied
- no ions are free to move
- barium sulfate is solid
- and the hydrogen ions produced water so no ions free to move and carry charge
34
what is a base
give an example? what is an alkali?
a substance that reacts with an acid to make a salt
- an alkali is a type of base that dissolves in water to form a ph greater than 7
35
what does a substance contain to make it an alkali
OH- ions
36
what does a acid+ base/alkali make
salt + water
37
what is an acid
aquaous solution with ph less than 7 with H+ ions
38
what is the ph a measure of
the concentration of H+ ions
39
what are the ions if a solution is neutral
conc. of H+ = conc of OH-
40
give the ionic equation for H+ etc.
H+ + OH- ---> H2o
* reaction is reversible
41
what is a strong acid
completely ionises in water
eg. HCl --> H+ + Cl-
eg, nitric,sulfuric, hydrochloric
42
what is a weak acid
partially ionises in water
eg, ethanoic acid, citric, carbonic
- reaction is reversible
43
conc of H+
- 0.1= 10^-1= ph is 1
- 0.01 = 10^-2= ph is 2
- 0.001 = 10^-3= ph is 3
44
acid + metal oxide
acid + metal hyroxide
---> salt + water
45
what is the carge of ion copper (11)
Cu 2+
46
acid + metal carbonate
salt + water+ carbon dioxide
47
how does something become more conc.
more molecules in same volume
48
how does something become more acidic
ore acidic as more H+
49
acid+ metal
salt + hydrogen
50
metal + water
metal hydroxide + hydrogen
- less reactive metals dont react with water
51
how are gold,silver and platinum found
they are unreactive so found as natural element
52
what is reduction and oxidation in terms of electrons
oxidation - loss of electrons
reduction- gain of electron
53
what is the ionic equation for iron and copper
overall equation
Fe+ CuSO4 --> FeSO4 + Cu
SO4 are spectator ions- dont change
ionic equation
Fe + Cu2+ --> Fe2+ + Cu
FE TO FE2+ IS OXIDATION
CU2+ TO cU IS REDUCTION
- Fe--> Fe2+ + 2e-
- Cu2+ + 2e- ----> Cu
54
what should you use for electrodes and electolyte
- use graphite and carbon electrodes as unreactive and good at conducting electricty
- electrolyte is molten or dissolved so ions are free to move and carry charge
-
55
what happens at the cathode (-and anode(+) in electolysis of molten
cathode- is always reduction
Al3+ + 3e- --> Al
anode- is always oxidation
202- ---> 02 + 4e-
56
describe the separation of alumium
alumium ore is called bauxite which contains alumium oxide which is separted by electolysis
- expensive as use of energy in electrolysis eg, melt it and use electricty to separate it
57
what substance can you add to make it electolysis cheaper
- add cryolite to lower mp so less energy needed so less ff, co2 and greenhouse gases
58
what is in an aquoues solution
there are ions and water
59
what is produced at the cathode in electrolysis of an aqueous solution
1. if H+ ions and metal ions present, hydrogen gas will be produvced if metal is more reactive than hydrogen
2. if metal is less reactive tha hydrogen metal is produced
LESS REACTIVE SUBSTANCE IS PRODUCED
60
what is produced at the anode in electrolysis of an aquoeus solution
1. if halide ions present, they are formed
2. if no halide ions oresent, OH- will go and produce oxygen gas
61
what is produced at the anode and cathode of copper sulfate solution
cathode-copper produced as less recative than hydrogen
anode- oxygen gas as no halide ions
62
what is the ionic equation for the production of oxygen from hydroxide
OH- ---> O2 + H2O + E-
BALANCE IT
63
what ions are present in sodium chloride solution and what is produced at each electrode
- OH-, H+, Na+, Cl-
cathode- hydrogen gas as sodium more reactive than hydrogen
anode- chlorine as halide ions present
64
what is an exothermic reaction and explain what the reaction profile looks like for it
give examples of reactions
- transfers energy to surroundings whihc is hown by a rise in temperature
- products have less energy than reactants so are lower down
- neutralisation, burning fuels,
65
what is an endothermic reaction and explain what the reaction profile looks like for it
give examples of reactions
- takes in energy from surroundings shown by fall in temp
- products have more energy than reactants so are higher
- thermal decomposition
66
how does bonds link to exo and endo reactions
EXO= bonds forming is exothermic, energy released when new bonds formed
H +Cl --> HCl + energy released
ENDO= bonds breaking is endothermic, energy is supplied to break existing bonds
Cl2 --> Cl + Cl
67
how are exo and endo reactions used in real life
EXO=hand warmers, as oxidation of iron in air to release energy, self heating cans
ENDO= spirt injury packs, become instantly cooler
68
what type of reaction has a negative overall energy change? positive enrgy change?
- exothermic is negative
- endothermic is positive
69
what do you use in cells to get a big voltage
- 2 different metal electrodes, the bigger the difference in reactivity between metals the bigger the voltage
- change electolyte and conc. (more conc. bigger voltage) of it to get a bigger voltage
70
what is a non rechargeable and rechargeable battery
non rechargeable is a chemical reaction that is irreversible as reactants are used up
rechargeable is reverible
71
what is a fuel cell
- electrical cell supplied with a fuel and oxygen and uses energy from reaction to produce electricity
72
what is good about hydrogen- oxygen fuel cells compared to batteries
- dont produce as many pollutants
- only by product is heat and water
- batteries more polluting to dipose of as made from highly toxic metal
- batteries are rechargable
- batteries more expensive than fuel cells and store less energy and have to be recharged more often
