Topic 1: Atomic structure and the periodic table Flashcards
(96 cards)
1
Q
where is the nucleus found?
A
in the middle of the atom
2
Q
what does the nucleus contain?
A
protons and neutrons
3
Q
what is the nucleus’s charge?
A
positive
4
Q
where are the electrons located?
A
around the nucleus in shells
5
Q
what are the electrons charge?
A
-1
6
Q
what are the electrons mass?
A
very small
7
Q
what is the nucleus’s relative mass?
A
1
8
Q
what is the protons relative mass?
A
1
9
Q
what is an atoms overall charge?
A
neutral
10
Q
why are atoms neutral?
A
because the number of protons in an atom is equal to the number of electrons
11
Q
what is an ion?
A
an atom when the number of protons doesn’t equal the number of electrons
12
Q
what does the atomic number (small one) on an atom tell you?
A
the number of protons
13
Q
what does the mass number (big one) tell you?
A
the number of protons and neutrons this is the mass of the atom
14
Q
how do you work out the number of neutrons in an atom?
A
mass number - atomic number
15
Q
what decides what type of atom an atom is?
A
the number of protons in the nucleus
16
Q
what is an element?
A
a substance made of one type of atom
17
Q
what is an isotope?
A
a substance with a different number of neutrons
18
Q
what is the formula for relative atomic mass?
A
Ar=sum of (isotope abundance x isotope mass number) / sum of abundances of all the isotopes
19
Q
copper has two stable isotopes Cu 63 has a abundance of 69.2% and Cu 65 has a abundance of 30.8% calculate the relative atomic mass?
A
(69.2 x 63)+(30.8 x 65) / 69.2+30.8 = 63.6
20
Q
what is a compound?
A
a substance formed of two or more elements
21
Q
how are bonds made?
A
by electrons sharing or swapping electrons
22
Q
what is ionic bonding?
A
when a metal and a non-metal react by swapping electrons
23
Q
what is covalent bonding?
A
when two non-metals react by sharing electrons
24
Q
what elements formed to make CO2?
A
1 carbon
2 oxygen
25
what elements formed to make Ca(OH)2
1 calcium
2 oxygen
2 hydrogen
26
how can you show a chemical reaction?
by writing down the products and then an --> and then the reactants eg magnesium + oxygen --> magnesium oxide
27
what is a symbol equation?
writing down the symbols instead of writing the equation long hand
28
why do you need to balance equations?
because mass cannot be gained or lost in a chemical reaction
29
balance the equation Fe + Cl2 --> FeCl3
2Fe + 3Cl2 --> 2FeCl3
30
what is a mixture?
a substance formed of atoms that are not all chemically bonded
31
when a compound is formed what happens to its properties?
the properties would be completely different from the individual atoms
32
when a mixture is formed what happens to its properties?
the mixture would have similar properties to the individual atoms properties
33
REQUIRED PRACTICAL: how do you use chromatography to separate dyes in ink?
1) draw a line near the bottom of a sheet of filter paper
2) add a spot of the ink to the line and pace the sheet in a beaker of solvent eg water
3) the solvent used depends on whats being tested some compounds dissolve well in waterbut sometimes stuff like ethanol is needed
4) make sure the ink isn't touching the solvent
5) place a lid on the top to stop the solvent evaporating
6) the solvent seeps up the paper carrying the ink as well
7) each dye will move at different speeds as the dyes separate out
8) if the ink is insoluble they will stay on the baseline
9) when the solvent has nearly reached the top of the paper leave the paper to dry
10) the end pattern of spots is called a chromatogram
34
REQUIRED PRACTICAL:how to separate using evaporation?
1) pour the solution into an evaporating dish
2) slowly heat the solution the solvent will evaporate and the solution will get more concentrated eventually crystals will start to form
3) keep heating the evaporating dish until all you have left are dry crystals
35
REQUIRED PRACTICAL:how to separate using crystallization?
pour the solution into an evaporating dish and gently heat the solution some of the solvent will evaporate and the solution will get more concentrated
2) once some of the solvent has evaporated or when you see crystals start to form remove the dish from the heat and leave the solution to cool
3) the salt should start to form crystals as it becomes insoluble in cold highly concentrated solution
4) filter the crystals out of the solution and leave them in a warm place to dry you could also use a drying oven or a desiccator
36
REQUIRED PRACTICAL:how to separate rock salt using filtration and crystallization?
1) grind the mixture to make sure the salt crystals are small so will dissolve easily
2) put the mixture in the water and stir the salt will dissolve but the sand wont
3) filter the mixture the grains of sand wont fit through the tiny holes in the filter paper so they collect on the paper instead the sale passes through the filter paper as it is part of the solution
4) evaporate the water from the salt so that it forms dry crystals
37
REQUIRED PRACTICAL:how to separate using simple distillation?
1) it is used to separate out a liquid from a solution
2) the solution is heated the part of the solution that has the the lowest boiling point evaporates first
3) the vapor is then cooled , condenses (turns back to the liquid) and is collected
4) the rest of the solution is left behind in the flask
5) you can use simple distillation to get pure water from sea water the water evaporated and condensed and collected eventually you will end up with just the salt
6) the problem with simple distillation is that you can use it to separate things with very different boiling points - if the temperature goes higher than the boiling point of the substance with the higher boiling point they will mix again
7) if you have a mixture of liquids with similar boiling points you need another method to separate them - like fractional disstilation
38
REQUIRED PRACTICAL:how to separate using fractional distillation?
1) if you have a mixture of liquids you can separate it using fractional distillation here is a lab demonstration that can be used to model fractional distillation of crude oil at a refinery
2) you put your mixture in a flask and stick a fractional column on top then you heat it
3) the different liquids will have a different boiling points so they will evaporate at different temperatures
4) the liquid with the lowest boiling point evaporates first when the temperature on the thermometer matches the boiling point of this liquid it will reach top column
5) liquids with higher boiling points might also start to evaporate but the column is cooler towards the top so they will only get part of the way up before condensing and running back down towards the flask
6) when the first liquid has been collected you raise the temperature until the next one reaches the top
39
who first described atoms as solid spheres?
john Dalton
40
what did jj Thompson discover about the atom?
in 1897 he found out that atoms contain electrons and came up with the plum pudding model
41
what was the plum pudding model?
a positively charged ball with electrons inside it
42
how was the plum pudding model proved wrong?
by Rutherford by shooting alpha particles at thin sheets of gold if the plum pudding model was true the particles would be deflected back because the positive circle would deflect the particle because they are both positive
43
what was the nuclear model of the atom?
a tiny positive nucleus at the center where most of the mass is concentrated a cloud of negative electrons surround so the atom is empty space
44
who came up with the nuclear model of the atom?
Rutherford
45
who first proposed the idea of electrons being in shells?
Bohr
46
why would electrons have to be in shells?
because otherwise they would be attracted to the nucleus
47
who discovered protons?
Rutherford
48
who discovered neutrons?
James Chadwick
49
how many electrons are allowed in each shell?
1 st: 2
2nd: 8
3rd: 8
4th: 8........
50
what is the electronic structure of nitrogen?
2,5
51
what is the electronic structure of magnesium?
2,8,2
52
in the old periodic table what where the most obvious ways to categorize atoms?
1) properties
| 2) relative atomic mass
53
who came up with the periodic table and when?
1869 Dmitri Mendeleev
54
how is the periodic table sorted?
in order of atomic number (protons) and so elements of similar properties are in colums, know as groups it is called the periodic table because similar properties occur at similar intivals
55
what confirmed that Mendeleev was right to use properties to sort elements as well as atomic mass?
isotopes as they have the same properties but would be placed differently
56
where are elements with similar properties placed?
in columns/groups
57
how can you tell from the periodic table how many electrons are in the atoms outer shell?
the group number tells you
58
what are the rows on the periodic table called?
periods
59
what are metals?
elements which can form positive ions when they react
60
where are non-metals on the periodic table?
top right
61
why do atoms react?
to gain a full outer shell
62
why do elements at the bottom of the periodic table react more?
the electrons are held in place less by the attraction between them and the nucleus as they are further away from the nucleus
63
what are properties of metals?
- they are strong
- they are great at conducting heat and electricity
- they have high boiling and melting points
64
where are transition metals on the periodic table?
in the middle
65
what are transition metals's properties?
- can have more than one ion
- often colored and so compound that contain them are colorful
- transition metal compounds make good catylists
66
what are group one metals?
alkali metals
67
how reactive are group one metals?
very reactive as they only have one electron in their outer shell
68
what are group one metals properties?
- soft
- low density
- very reactive
69
what are the trends as you go down group one?
- increasing reactivity
- lower melting and boiling points
- higher relative atomic mass
70
what happens if a group one metal reacts with water?
- react vigorously to produce hydrogen gas and metal hydroxides
- the amount of energy given out by the reaction increases down the group
71
what happens if a group one metal reacts with chlorine?
- react vigorously
| - forms metal chlorine salts
72
what happens if a group one metal reacts with oxygen?
- lithium reacts to form lithium oxide
- sodium reacts to form sodium oxide and sodium peroxide
- potassium reacts to form potassium peroxide and potassium super oxide
73
what are group seven atoms?
halogens
74
what happens as you go down group seven the halogens?
1) become less reactive - harder to gain electrons as they are further from the nucleus
2) higher melting and boiling points
3) higher relative atomic mass
75
how can halogens gain a full outer shell?
by covalent bonds
76
what is a displacement reaction?
when a more reactive substance replaces a less reactive one
77
what are group 0 elements?
noble gases they are nonreactive and do not easily form molecules because there atoms have stable arrangements of electrons (8 electrons in outer shell)
78
what are group 0 gases?
monatomic gases - not bonded to anything
79
what happens as you move down the group 0 atoms?
boiling point increases
80
Neon is a gas at 25 degrees predict what state helium is at this temperature?
they are in group 0 boiling point increases down group 0
| so helium must be a gas
81
Radon and krypton have boiling points of -62 degrees and 153 degrees respectively predict the boiling point of xenon?
xenon is between the radon and krypton so you can predict that its boiling point is half between theirs
- 153+-62=-215
- 215/2=-107.5 = 108 degrees
82
why do elements in the same groups have similar properties?
because they have the same amount of electrons in their outer shell
83
before the electron, proton or neutron was discovered how where elements organised?
in order of atomic weight
84
what was wrong with the old periodic tables?
tables where incomplete and elements where placed in innerproriot groups
85
how did mendeleev overcome the problems with the preiodic table?
he left gaps for elements that have not been discovered and in some places changed the order of atomic weight - elements with properties predicted by mendeleev where discovered and knoledge of isotopes made it possible to explain why atomic weight was not always coorect
86
what is an atom?
the smallest part of an element that can exist and makes up everything
87
how can atoms be represented?
by symbols eg 0 for oxygen Na for sodium
88
where are elemnets shown?
in the periodic table there are about 100 elements
89
how are compounds formed?
from elements by chemical reactions - they can only be seperated by chemical reactions
90
what where atoms thought to be before the discovery of the electron?
tiny spheres that could not be divided
91
what did the alpha particle scattering experiment conclude?
the mass of an atom was concerntrated in the nucleus and the nucleus was charged
92
what did neils bohr discover?
that electrons orbit at specific distances the thoeretcila calculations of bohr agreed with experimental observations
93
who discovered there where neutrons in the nucleus?
james chadwick
94
what is the radius of an atom?
0.1 nm (1x10to the -10 m)
95
what is the radius of a nucleus?
1/10000 of the size of an atom (1x10 to the -14)
96
where is the mass of the tom contained?
in the nucleus
