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Chemistry > Atomic structure and periodic table > Flashcards

Atomic structure and periodic table Flashcards

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1
Q

what is a molecule

A

a group or 2 or more atoms held by chemical bonds-
eg -o2 cl2 n2 c2o c2o

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2
Q

what are compounds

A

substances that contain 2 or more different elements
eg- h2o,c2o,

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3
Q

what is a key feature of compounds

A

they are always found in the same proportion

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4
Q

what are mixtures

A

2 or more substances that are not chemically combined

  • only physically mixed together
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5
Q

soluble

A

dissolves in solvent

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6
Q

solute

A

substance that dissolves

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7
Q

solvent

A

liquid it dissolves in

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8
Q

solution

A

liquid formed

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9
Q

what does filtration seperate

A

insoluble solids from liquids through filter paper in filter funnel

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10
Q

how do we get a dissolved soluble solid from a solution

A

evaporation or crytallisation

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11
Q

explain evaporation

A

place solution in evaporating dish on tripod
slowly heat with bunsen burner
solvent evaporates and remaining solution becomes more concentrated
leaves us with dry solid crytals

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12
Q

issues with evaporation

A

some solids decompose when heated(thermal decomposition)
it is broken down into something other than what we need

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13
Q

explain crystallisation

A

place solution into evaporating dish
heat gently with water bath rather than bunsen burner
when some of solvent evaporates and crystals start to appear leave it to cool so more crystals form( solids are less soluble at lower temp)
filter out crystals from the remaining solutions and dry crystals by leaving it somewhere warm or warming it in an oven

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14
Q

why is simple distillation used

A

to seperate liquid from solution or liquid mixture

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15
Q

explain simple distillation and equipment

A

flask with bung with thermometer fit through containing solution
connected to a condenser coated by a water jacket with stream of flowing cold water(goes in through bottom and out through top)2`
at the end there is a beaker to collect the pure liquid
we need a heating device under flask like mixture

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16
Q

explain simple distillation

A

heat mixture so desired liquid so it evaporates and high pressure will send it down condenser and the cold water will cool the vapour which will run down the pipe and enter beaker leaving only solute in the flask

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17
Q

equipment for fractional distillation

A

flask contains solution and is heated to temp of the liquid with the lowest bp
The vapour pass through fractionating column (full of glass rods, cooler at top than bottom)
passes into condenser and condenses to liquid into the beaker.

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18
Q

atomic theory

A

back in 500 bc democritus suggested everything was made of small indivisble spheres which were surrounded by empty space

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19
Q

in 1800s who and what was involved in the development of atoms

A

John Dalton: described atoms as solid spheres and suggested that different types of spheres make up the different elements

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20
Q

in 1897 who contributed to development of the atom and how

A

JJ thompson came up with the plum pudding model
He did experiments that proved atoms couldnt be just solid spheres and must have contained negative charged particles
His model was a ball of positive charge with discreet electrons stuck in it

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21
Q

what happened in 1909 in development of the atom

A

ernest rutherford: in 1909 took + charged alpha particles and fired them at thin sheet of gold
resulted in some alpha particles reflected to side and some sent back completely- deflected
proved jj thompson theory wrong - idea that spread out positive charge wouldnt be strong enough to stop alpha particles and would be spread out

he suggested a nuclear model which said there was a compact nucleus with all positive charge and negative charge was in a cloud around central nucleus
flaw was that there was nothing stopping cloud of negative electrons rushing in to +nucleus

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22
Q

what in 1913 developed atom

A

Neils bohr:in 1913 suggested that electrons orbited nucleus and were held in shells which prevents the atom from collapsing

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23
Q

what did further experiments by rutherford suggest

A

+ charge of nucleus is made up of small discrete particles called protons

24
Q

what is meant by an atom being unstable

A

it wants to react with another atom to gain a full outer shell

25
Q

when drawing ions what 2 things do you need to do

A

the charge in the top right corner
square brackets all around the ion

26
Q

what did mendeleev do

A

-he devised the periodic table that organised all of known elements
-he predicted undiscovered elements

27
Q

what are the elements arranged by

A

increasing atomic number(no of protons)

28
Q

what is the mass number

A

total number of protons and neutrons

29
Q

why did mendeleev create periods

A

he found that the elements displayed patterns of chemical properties that repeated at regular intervals and formed new rows which we call periods

30
Q

list some trends in group 1 elements

A

-they become more reactive as you go down the group
-they all react violently with water

31
Q

what are trends with halogens

A

they become less reactive as you go down the group

32
Q

what do atoms in the same period(rows) have the same

A

no of shells

33
Q

metals form what when they react

A

positive ions(eg Ca2+)
-they lose electrons

34
Q

what do non metals form

A

negative ions (eg:chlorine)
or don’t form ions (eg:carbon)
-they gain or dont gain electrons

35
Q

what does the positive nucleus do in an atom and why is this important

A

if the electrons are far away the nucleus cant hold on to them as strongly and so they are easily lost to form positive ions

36
Q

atoms further down the group are more reactive because

A

they are more likely to lose their electron during a reaction

37
Q

physical properties of metals

A

-they have metallic bonds
-malleable
-high melting point and boiling points
-shiny
-sonorous
-good heat and electricity conductors

38
Q

what are physical properties of non metals

A

-dull
-brittle
-low melting points and boiling points many being gaseous at room temp
-poor conductors of electricity
-low density

39
Q

what are the extra properties transition metals have over other metals

A

-they can form more than 1 ion which are often coloured (eg chromium which forms 2+(which is blue) 3+(which is green ) and 6+(which is orange)
-very good catalysts(eg iron in the haber process )

40
Q

list some features of alkali metals

A

-low density
-low melting point
-soft
-more reactive
-react vigorously with water /oxygen and group 7 elements

41
Q

why do alkali electrons become more reactive going down the group

A

the radius increases so the outer shell gets further from positive nucleus.
this means the attractive force between the positive nucleus and the atoms outer most electron meaning the electron can be lost more easily increasing the atoms reactivity

42
Q

how do alkali metals and halogens form ionic compounds

A

the halogen will gain the alkali metals outer shell electron so both have full outer shells forming oppositely charged ions which are attracted to each other by electrostatic forces called an ionic bond
an example of this is table salt
they generally form white solids and dissolve in water to form colourless solutions

43
Q

how do alkali metals react in water

A

reacts vigourously forming metal hydroxide +hydrogen gas

44
Q

after pottasium reacts with water the energy released ignites hydrogen gas .What form do we see this in?

A

as flames

45
Q

how do alkali metals when heated with chlorine gas

A

they form white metal chloride salts

46
Q

what happens when alkali metals react with oxygen

A

they form metal oxides

47
Q

potassium +oxygen forms

A

ko2 or k2o2

48
Q

sodium +oxygen

A

na2o2 or na2o

49
Q

what type of molecules are halogens

A

-diatomic molecules

50
Q

list trends that occur with halogens as you go down the group

A

-reactivity decreases
-boiling and melting points increase

51
Q

why does the reactivty decrease

A

because as you go down the group the outermost shell gets further away from the positive nucleus so the force of attraction to pull in extra electron gets weaker

52
Q

how do they react and form ionic bonds with metals

A

they form halide ions with a 1- ions and these are most common with alkali metals

53
Q

what are all noble gases

A

-group 0 colourless gases-exist as single atoms and are non flammable
-their melting and boiling points increase going down the group

54
Q

what are some colour changes that take place in halogen displacement reaction

A

Halide salts (e.g. KCl, KBr, KI) are colourless
Bromine water is orange
Chlorine water is colourless
Iodine water is brown

55
Q

list the colours and physical states of the halogens at room temperature

A

-Fluorine is a poisonous yellow coloured gas and is the most reactive halogen
-Chlorine is a green coloured gas.
-Bromine is a red-brown volatile liquid which is also poisonous.
-Iodine is a grey coloured solid with purple vapours.

56
Q

noble gases trend

A

bp increases down group
have full outer shell (not 8)

57
Q
A

Chemistry (6 decks)

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