c1 atomic structure and the periodic table Flashcards
(79 cards)
1
Q
define atom
A
the smallest part of an element that can exist
2
Q
what are the groups on the periodic table
A
vertical, 1-7 then 0
3
Q
what are periods on the periodic table
A
horizontal
4
Q
how to separate a mixture
A
physical processes:
filtration - insoluble solid from liquid
crystallisation - soluble solid from solution
distillation - liquid from a solution
fractional distillation - liquid from mixture of liquids
chomatography - mixture of dyes
5
Q
which elements exist as molecules made up of two of the same atoms joined together
A
iodine, bromine, chlorine, fluorine, oxygen, nitrogen, hydrogen
6
Q
how do you remember the elements that are written as (element)2
A
I Bring Clay For Our New House
7
Q
define compound
A
a substance that contains two or more elements that are chemically combined in fixed proportions
8
Q
what does it mean if the second word of a compounds name starts with mon, di or tri
A
its made up of non metals only, and shows how many there are of that element for every one atom of the first element. e. g carbon dioxide, one carbon to two oxygen (C02)
9
Q
what is an ion
A
and charged particle formed when an atom or a group of atoms loses or gains an electron
10
Q
how does simple distillation work
A
- solution placed in flask and heated by bunse burner
- liquid evaporates, vapour passes through glass tube which has thermometer attached
- tube surrounded by condenser, with cold tap water continuously running through to cool the vapour
- vapour passes through and condenses
- liquid formed (pure distilled water) collected in beaker
11
Q
how does fractional distillation work
A
- solution of multiple boiling points placed in flask and heated
- liquids evaporate, mixture of vapour passes through fractionating column, which contains hundred of glass beads
- liquid with lower BP evaporates more easily. liquid with higher BP condenses in glass beads and drip back into flask, as tube is cooler nearer top
- when thermometer reads lowest BP, that liquid has reached the top and can condense in condenser and be collected
- flask continues to heat, so next liquid can be collected
12
Q
what is a reactant
A
The substances that react together in a chemical reaction
13
Q
what is an aqueous solution
A
forms when a substance dissolves in water
14
Q
What is the law of conservation of mass?
A
total mass of the product is equal to the total mass of the reactants
- no atoms lost or gained
15
Q
when might mass of products be larger
A
if a gas has become a solid, its mass can be measured
16
Q
What is a plum pudding model?
A
A ball of positive charge with negative electrons studded into it
17
Q
how were elements originally arranged, and why was this inaccurate
A
- in triads of similar chemical properties
- atomic weight, as every 8th element reacts similarly
however, protons were not discovered so atomic weight could be affected by isotopes, meaning sometimes elements with different properties were grouped
18
Q
how did mendeleev develop the first periodic table
A
- ordered elements by atomic weight, but swapped some to fit the physical and chemical patterns of other elements within group
- left gaps in periodic table for undiscovered elements, predicting properties
19
Q
Why was mendeleevs table accepted
A
- elements discovered fit gaps he left
- elements discovered properties were correctly predicted
20
Q
what is atomic weight now?
A
relative atomic mass
21
Q
how has the periodic table changed since mendeleev
A
- protons discovered, so elements arranged by atomic number rather than weight. this puts them in correct order as the presence of isotopes affects atomic weight
- group 0 added
22
Q
what is the relative atomic masses of the subatomic particles
A
protons and neutrons: 1
electrons: 0
23
Q
what are the charges of the subatomic particles
A
protons: positive
neutrons: neutral
electrons: negative
24
Q
what is an isotope
A
different forms of the same element that have the same number of protons but a different number of neutrons
25
what does abundance mean
how common or rare that isotope is
26
what is the equation for relative atomic mass
sum of (isotope abundance x isotope mass)
————————
100
27
define molecule
2 or more atoms held together by chemical bonds
28
how do you find percentage mass of an element
mass of element
————————- x 100
total mass of compound
29
What is paper chromatography?
A process used to separate mixtures of soluble substances
30
how does chromatography work
The solvent dissolves the different substances in the mixture and carries them up the paper
each are attracted to the two phases in different proportions, meaning they spend different amounts of time in each
This causes pure substances to form one spot and impure to form multiple
31
what are the two phases in chromatography?
The stationary phase and the mobile phase
32
how can you tell if two substances are the same on a paper chromatogram
- same spots of same colours
- same distance up paper
33
whose had the first ideas about atoms and what were these ideas
John Dalton- all matter was made a tiny particles called atoms, which he imagined as tiny spheres that couldnt be divided
34
what did jj thompson do
JJ Thompson - discovered atoms contain negatively charged paarticles, electrons.
designed plum pudding model
35
how was the plum pudding model tested and who did it
Ernest Rutherford - rutherford scattering experiment
positively charged alpha particles were fired at thin gold foil. Most of the particles went through the foil,
showing that the gold atoms were mostly empty Space
a few were scattered in different directions or bounced back, showing that mass of atoms is concentrated in the centre, positively charged
36
What did Ernest create?
A new model called the nuclear model.
the mass of an atom is concentrated at its centre, the nucleus.
And the nuclues positively charged
electrons orbit in paths
37
who adapted the nuclear model and what did he discover
niels bohr, discovered that electrons orbit the nucleus at fixed distances, known as energy levels
38
what was dicovered after niels
the nucleus contain small particles called protons, which each had a small amount of positive charge.
39
Who discovered neutrons?
James Chadwick
40
how to identify group of element from structure diagram
number of electrons in outer shell
41
radius of an atom vs radius of nucleus
1x10^-10m (0.1nm)
1x10^-14
atom is over 10 000 x bigger than nucleus
42
what are groups arranged in?
Elements with similar properties
43
what happens when metals reaxt
they form positive ions, as they lose electrons to get a full outer energy level (become stable
44
properties of metal
conductor
shiny
high-density
malleable
ductile
high BP and MP
45
properties of nonmetals when solid
Poor conductor
dull
low-density
brittle
low BP and MP
46
What are elements in group 0 called and what are some properties
Noble gases
- unreactive
- BP lower that room temp
47
why are noble gases unreactive
outer shells are full, atoms are stable
48
How did the elements change as you go down group 0
- boiling point increase as there are more intermolecular forces as atoms become larger (more energy needed)
49
what are group 1 elements called?
Alkali metals
50
Properties of alkali metals
soft
relatively low melting points
low density
highly reactive
form 1+ ions
51
properties of transition elements
hard and strong
high melting point
high density
low reactivity
form ions with different charges
form coloured compounds
used as catalysts
52
how do group 1 metals react with oxygen
react rapidly to form metal oxide
- 2 alkali metals lose one outer electron to oxygen, eg lithium forms Li2o
53
how do group 1 metals react with chlorine
react rapidly to form metal chloride
- flame
- white solid forms
- colour of gas fades
54
how do group 1 metals react with water
reacts to form metal hydroxide and hydrogen
- effervescence of fizzing, meaning gas (hydrogen) produced
- universal indicator changes colour, meaning alkaline solution (metal hydroxide) produced
eg lithium becomes LiOH + H2
55
how do reactions with water change and you go down group 1
- disappears quicker
- fizzes more vigourosly
- ignites more vigorously
- moves across surface faster
56
how do the different group 1 metals react to being placed in water, eg potassium
they will react faster and give out more energy as you go down
- potassium releases enough energy to ignite hydrogen
57
what happens to elements as they go down group one?
- they get more reactive. as you go down group, atom becomes larger, meaning negative outer electron becomes further from positive nucleus, so are lost more easily. electrons also repel outer electrons
- lower MP and BP
58
What is group 7 called
Halogens
59
how are group 7 atoms found
as molecules, two atoms joined by covalent bond
60
What happened to elements as you go down group 7
- less reactive. atom becomes larger, meaning outser shell becomes further. this makes it hader to gain extra electron as there is a weaker attraction to positive nucleus. electrons also repel outer electrons
- less likely to displace other halogens
- MP and BP increase
- molecules become larger
61
how do group 7 elements react with non metals
covalent bonding
they will share outer electron to form molecular compound
62
how do group 7 elements react with metals
ionic bonding to form metal-ide, eg fluorine becomes fluoride
they will gain electron from metal to become 1- ions
63
describe how displacement reactions can occur with group 7 elements
- more reactive halogen displaces less reactive halogen in aqueous solution of its salt
eg sodium bromide + fluorine:
fluorine is more reactive than bromine, so:
sodium fluoride + bromine
64
what is a mixture and what properties will it have
when different elements or compounds are not chemically combined
same properties as different components
65
how to use display on periodic table to get information about the atomic structure of ions
top number: mass number - number of protons and neutrons
bottom number: atomic number -number of protons
if 1+ charged: ion has 1 fewer electrons than protons
if 1- charged: ion has 1 more electrons than protons
66
how to use display on periodic table to get information about the atomic structure
top number: mass number - number of protons and neutrons
bottom number: atomic number -number of protons (and electrons)
67
what is empirical formula and how is it written
the simplest whole number ratio of atoms of each element of a compound
written as normal formula eg MgCl2
68
how to find empirical formula from dot and cross diagram
count how many atoms there are of each element
69
how to find empirical formula from 3d diagram
work out the charges the ions present will form
write how many of each ion is meeded to balance (full outer shell)a
70
how to find empirical formula from masses in compound
- divide each mass by its Ar
- divide values by the smallest number to get whole numbers
- write into formula
71
how to convert empirical formula to molecular formula
- find "Mr" of the atoms in empirical formula
- real Mr / shown Mr to find multiplier
- multiply empirical ratio by multiplier
72
why should halogen gases be experimented inside of a cupboard
halogens are toxic
73
if boiling point is 56 and melting point is 7, at what temperatures will the substance be solid/liquid/gas
<7 - solid
7-56 liquid
>56 gas
74
why is it not correct to say the boiling point of a single molecule
boiling is a bulk property - it involves more than one molecule as it involves intermolecular forces
75
how do transition metals react
low reactivity
76
what does it mean by write formula"
same as empirical - simplest ratio
77
mp of hydrogen
very low
78
how can you tell something may be a catalyst from its formula
more little numbers
79
what colour are the halogens
fluorine: pale yellow
chlorine: yellow green
bromine: red brown
iodine: dark grey
