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emma, ella and sophie's study :) > Chemistry AOS#1 > Flashcards

Chemistry AOS#1 Flashcards

1
Q

atomic theory

A
  • -> matter is made of atoms
  • -> atoms cannot be broken down into smaller substances
  • -> elements contain only one type of atom in fixed ratios
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2
Q

nano meter

A

one billionth (10^-9) of a metre

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3
Q

nanotechnology

A

the use of technology to manipulate and investigate properties of substances on a nano scale

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4
Q

conversion chart

A

multiply by 1000 (10^3)

m–> mm–> μm –> nm

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5
Q

nanomaterials

A

have different properties than the same material in bulk form

they have a greater surface area to volume ratio (increased exposure to the environment)

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6
Q

nanotubes

A

allow for water to leave but keeps the salt inside of them used in salt water –> filtration plants

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7
Q

atomic number

A

number of protons in an atom

assigned the letter Z

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8
Q

mass number

A

mass number is represented by the letter A

the number of protons and neutrons

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9
Q

isotopes

A

when elements have same protons but different neutrons
eg. carbon 12, carbon 13, carbon 14

isotopes have same atomic number but different mass number

they have similar chemical properties –> electron configuration is the same
they have different physical properties –> different mass

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10
Q

atomic emission spectrum

A

when atoms are heated they give off electromagnetic radiation or light

gives clues about electonic structure of an element

  • -> atoms of the same element produce identical line spectra
  • -> each element has a unique line spectrum because of their unique electronic structure
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11
Q

bohrs model

A

electrons revolve around nucleus in fixed circular orbits

  • ->electrons orbits correspond to specific energy levels
  • -> electrons cannot exist between two energy levels
  • -> electrons in outershell have more energy than that of closer ones
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12
Q

excited state

A

electrons absorb energy and jumps to a higher energy level

  • -> the closest the electron is to the nucleus, the more energy is needed to move them to a higher state
  • ->when going back to the ground state, electrons release photons which is the light we see
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13
Q

subshells

A

within each shell, there are certain subshells with different energy levels

subshell fill with the lowest energy first
1s<2s<2p<3s<4s etc.
1s= lowest energy
4s = highest energy

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14
Q

the subshell ‘s’

A

one orbital

max number of electrons = 2

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15
Q

the subshell ‘p’

A

3 orbitals

max number of electrons = 6

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16
Q

subshell ‘d’

A

5 orbitals

max number of electrons = 10

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17
Q

subshell ‘f’

A

7 orbitals

max electrons = 14

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18
Q

electron configuration of chromium (24)

A

…. 3p^6 4s^1 3d^5

at the higher energy level, some electrons don’t want to be paired up, - negative charges repel - so they jump to the empty space in the next subshell

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19
Q

electron configuration of copper (29)

A

3p^6 4s^1 3d^10

one electron from 4s^2 moves to 3d subshell to avoid being parted up because both are negatively charged.

copper and chromium will only EVER have 4s^1

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20
Q

ions

A

have an imbalance between protons and electrons

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21
Q

groups

A

have the same physical and chemical properties. groups go down the periodic table

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22
Q

periods

A

represents the number of electron shells present

–> period 2 = 2 electron shells

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23
Q

core charge aka. effective nuclear charge

A

the measure of attractive force felt by valence electrons towards the nucleus

core charge = number of protons - number of innershell electrons (not valence)

group 1 has a low core charge –> want to give away their electrons
group 18 has a high core charge –> doesn’t want to give away their electrons

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24
Q

atomic radius

A

measurement of the size of the atom

  • -> the distance from the nucleus to outermost electrons
  • -> small core charge = larger atoms as electrons are not held as tightly towards the nucleus
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25
Q

electronegativity

A

the ability of an element to attract electrons towards itself

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26
Q

core charge trends

A

increases across a period, and no change down a group

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27
Q

electronegativity trends

A

decreases down a group, increases across a period

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28
Q

atomic radius trends

A

increases down a group (as there is more electrons), and decreases across a period

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29
Q

first ionisation energy

A

amount of energy required to remove one electron from an element in the gas phase

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30
Q

first ionisation energy trends

A

decreases down a group, increases across a period

mirrors the core charge going left –> right

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31
Q

first ionisation energy trends

A

decreases down a group, increases across a period

mirrors the core charge going left –> right

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32
Q

metallic characteristic trends

A

moving left to right on the periodic table, the metallic characteristics decrease
–> the number of electrons found in valence shell increases, therefore there is a less possibility of forming a positive ion

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33
Q

zinc

A

zinc is unlike other transition metals as it has a full 3d subshell. transition metals also form more than one cation, although zinc will only form a 2+ ion when two electrons drop from the 4s shell.

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34
Q

reducing strength of elements

A

the ability for an element to lose electrons

–> increases with the core charge along a period

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35
Q

trends of reactivity

A

reactivity along a period is like a parabola

–> chlorine and sodium is more reactive than iron

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36
Q

when it is easiest for atoms to lose electrons?

A

it is easiest when going down a group as the atomic radius increases, meaning the valence electrons are less attracted to the nucleus (further away) and electronegativity decreases

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37
Q

nuclear charge

A

aka. the actual charge on a nucleus

total charge found within a nucleus
–> increases across a period

–> number of protons

38
Q

ionisation energy vs electronegativity

A

ionisation is the energy required to remove an electron from a gaseous atom, whilst electronegativity is the ability for the nucleus to attract an electron. it is essentially the opposite

39
Q

why do metals have lower electro negativities?

A

as you move from left to right along a period, the number of protons increases by one, meaning the electronegativity will need to increase with the positive charge of the nucleus

40
Q

characteristics of metals

A
  • -> high melting points
  • -> conducts electricity
  • -> malleable (punchable and it holds its shape)
  • -> ductile (can be stretched - think wire)
  • -> high density (more matter)
  • -> lustrous (shiny)
  • -> low electronegativities (gives electrons away/low core charge)
  • -> low ionisation energy (energy required to lose an electron)
41
Q

properties of transition metals

A

d - block elements

42
Q

crystals

A

for metal to bend, atoms must slide over each other.

Metals with neatly packed atoms will bend easier than those that are not.
A metal with large grains (perfect close packing as shown on ball-bearing model) will have fewer dislocations and bend easier than small grains

43
Q

properties of s block metals

A

highly reactive

  • -> s1 metals are highly reactive
  • -> s2 metals are less reactive than s1 but still very reactive
44
Q

properties of p block metals

A

have varying properties

45
Q

properties of d block metals

A
  • -> formed coloured compounds
  • -> display magnetism
  • -> act as catalysts
  • -> high electric conductivity
  • -> high melting points
46
Q

reactivity of metals

A

can be determined by how readily they react with oxygen, water, steam, and dilute acids.

47
Q

reactivity trends

A

less reactive as they move along a period

more reactive as they move down a group

48
Q

metal + oxygen

A

metal + oxygen = metal oxide

–> 2Mg(s) + O2 (g) –> 2MgO(s)

49
Q

metal + water

A

metal + water –> metal hydroxide + hydrogen gas

–> 2Li (s) +2H2O (l) –> 2LiOH (aq) + H2 (g)

50
Q

metal + acid

A

metal + acid –> ionic salt + hydrogen gas

–> 2Li (s) + 2HCl (aq) –> 2LiCl (aq) +H2 (g)`

51
Q

lustre of metals

A

the mobile electrons within metals allow for light to be reflected back into your eyes, creating a shiny, lustrous appearance

52
Q

malleabiliy and ductile

A
  • -> positive cations repel from each other, but the negative electrons ensure attraction.
  • -> when bent hammered or pressed, the metal will still want to stay together because of the sea of electrons
  • -> layers of atoms can move past one another without disrupting the force between cations and electrons when force is applied
  • -> the non-directional nature of metallic bonds allows for this
53
Q

electrical conductivity

A

one end of the metal becomes positive and the other negative. all electrons are attracted to the positive end.
–> the electron flow is an electric current

54
Q

heat conductivity

A

when electrons gain kinetic/heat energy they are able to quickly transfer the heat to colder areas due to freedom of electrons

55
Q

density

A

metallic lattices are closely packed together creating a higher density

56
Q

melting point and hardness

A

metallic bonds are very tightly bound together so it is harder to break and boil.
–> melting points and hardness increase with the number of outer shell electrons

57
Q

metals in the earths crust

A

are found in the form of mineral compounds

–> oxides, sulfides, silicates

58
Q

only metals found in elemental states

A

only metals found in earths crust in their elemental states are platinum and gold
–> found in their raw form

59
Q

iron ore

A

occurs naturally in the earths crust

–> in australia, iron oxides in iron ore are usually in the form of haematite (Fe2O3)

60
Q

extracting iron from its ore

A

iron ore is mined from the groud and taken to the trucks for processing
–> causes damage to habitats, environment and culture

61
Q

steps in a blast furnace

A
  1. coke reacts with oxygen to make carbon dioxide
  2. limestone decomposes to calcium oxide
  3. carbon dioxide reacts with more coke to form carbon monoxide
  4. carbon monoxide reacts with iron oxide in ore to make liquid iron
  5. calcium oxide formed in step two reacts with sand in the ore, leaving slag.
62
Q

environmental impacts of iron production

A

loss of landscape
air pollution
noise pollution
disposal of slag

63
Q

economic impacts of iron production

A

significant financial benefit

significant wage gaps

64
Q

social impacts of iron mining

A

negotiations with indigenous people
land conflicts
workers have to fly to work in mines –> impact on family life

65
Q

methods used to minimise environmental impact of iron ore

A

reducing water and energy consumption
limiting waste production
recycling waste materials

66
Q

ways metals can be modified

A

through alloy production
heat treatment
coating

67
Q

why do metals need to be modified?

A

the way a metal can be used is based on its chemical and physical properties
most metals need to be modified to be useful

68
Q

alloy

A

metals that are melted and mixed with another substance

–> usually metal or carbon

69
Q

interstitial alloy

A

small proportion of an element with significantly smaller atoms added to the metal

  • -> added atoms sit in the gaps between cations making them not move as easy and hence stronger
  • -> steel (iron [big] and carbon [small ones]) is an example of this
70
Q

substitutional alloy

A

made of elements with similar size and chemical properties

  • -> the added element takes place of metal ions in the lattice
  • -> $2 coins is an example of this (copper, aluminium, and nickel)
71
Q

annealed metals

A

metals are heated until they are red hot and then are cooled slowly

  • -> results in larger crystals being formed
  • -> metals are softer
  • -> can be cut and shaped more easily
  • -> they bend when pressure is applied
72
Q

quenched metals

A

metals are heated until red hot and then are cooled quickly by being dunked in cold water

  • -> smaller crystals are formed
  • -> meaning metals become harder but more brittle
73
Q

tempered metals

A

quenched metals are warmed again (not to red hot) and allowed to cool slowly

  • -> it allows the crystals to settle
  • -> reduces the brittleness of the metal but retains hardness
74
Q

purpose of coating

A

coatings make metals more suitable for application

  • -> decorative purposes
  • -> functional purposes
  • -> Both!!
75
Q

noble coating

A

protection of metal by attaching a thin metallic layer to it

  • -> metallic layer is less reactive than steel
  • -> chromium is used as a noble coating on steel parts in cars and household items.
76
Q

sacrificial coating

A

protection of metal from corrosion by attaching a more reactive metal to it

  • -> when the metal is more reactive than steel
  • -> A break in a sacrificial coating results in the formation of an electrochemical cell. The coating corrodes and the steel is protected.
  • -> ex. zinc acts as a sacrificial coating on an iron roof. it reacts with CO2 in the air, forming zinc carbonate over the surface, protecting the metal and slowing the rate of corrosion
77
Q

work hardened metals

A

beating the metal when cold

  • -> causes crystal grains to become smaller
  • -> bending is made more difficult now - work hardened
  • -> example. bending a coathanger and then trying to bend it back to its original shape. it does not bend back in the area that has been work hardened.
  • -> usually more brittle
78
Q

uses of nano-silver

A

a useful antibacterial

79
Q

gold nanoparticles

A

can be used as a targeted chemotherapy method

80
Q

nano-iron

A

can remove carbon tetrachloride from rivers

–> can help control pollution

81
Q

ions

A

atoms that gain or lose electrons to achieve more stable outer shell electron configurations

82
Q

what charge does each group form

A 
group 1 = +1 cation
group 2 = +2 cation
group 13 = +3 cation
group 15 = -3 anion
group 16 = -2 anion
group 17 = -1 anion
83
Q

ionic lattices

A

cations and anions form to make a 3D lattice

  • -> held together by electrostatic forces of attraction between oppositely charged ions
  • -> ions in the lattice mirror the ratio found in the formula
    - -> CaF2 = 1:2 ratio of calcium to flourine
84
Q

very high melting points of ionic compounds

A

electrostatic attraction is strong between ions and a lot of energy is required to melt them apart.

85
Q

hardness and brittleness of ionic compounds

A
  • -> cannot be easily scratched
  • -> strong electrostatic attractions mean a strong force is required to disrupt the lattice
  • -> once the lattice is disrupted, it will shatter easily due to repulsion of like charges
86
Q

conducting electricity in an ionic compounds- solid, melted, aqueous

A

SOLID:
–> for a substance to conduct electricity, it must have moveable charges, but
ions in an ionic solid are fixed and have no free charged particles (ions are
charged
MELTED:
–> ions are free to move around and therefore are able to conduct electricity
because they have free charged particles
DISSOLVED:
–> ions are free to move around which means it can conduct electricity

87
Q

electrolyte

A

a liquid substance that conducts electricity

88
Q

why do ionic compounds dissolve in water?

A

water molecules are able to move between ions and free them, disrupting the structure of the lattice.
–> the attraction force between water and ions is stronger than the attraction
force between cations and anions

89
Q

factors affecting crystal formation

A

sizes of crystals are caused by the diverse conditions in which they are formed

  • -> the rate of evaporation affects the size of the crystal formed
  • -> slow evaporation results in larger crystals
90
Q

some uses of common ionic compounds

A

sodium hydrogen carbonate: cooking and cleaning
ammonium nitrate: fertilisers and explosives
nitrates, nitrites, sulfites: food preservation

91
Q

sports drinks

A

as we sweat we lose electrolytes

–> electrolyte is a substance that dissociates to form ions and dissolved readily into water

92
Q

hydrated ions

A

ionic compounds that contain water molecules bonded within the crystal
–> hydrates release water - which is a part of their structure - when they
decompose upon heating
example:
magnesium chloride hexahydrate = MgCl • 6H20

emma, ella and sophie's study :) (15 decks)

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