Chemistry Flashcards
(118 cards)
1
Q
What is Avogadro’s number?
A
6.02 x 10^23
2
Q
What does Avogadro’s number tell us?
A
the number of particles in a mole of a substance
3
Q
Which isotope are all other particles compared to when determining their relative mass?
A
Carbon - 12
4
Q
What order do the orbitals fill in (up to the end of the third energy level)?
A
1s2s2p3s3p4s3d
5
Q
What order do we write the orbitals when they have electrons in them?
A
1s2s2p3s3p3d4s
6
Q
What are the properties of metals?
A
Good conductors of heat and electricity, high melting and boiling points, malleable, ductile
7
Q
Describe the structure of a metal
A
A giant lattice with layers of positive ions surrounded by delocalised electrons
8
Q
Define the term ‘first ionisation energy’
A
The energy required to remove one mole of electrons from one mole of gaseous atoms
9
Q
Which factors affect the first ionisation energy?
A
Nuclear charge, shielding, atomic radius, spin-pair repulsion
10
Q
What shape are s-orbitals?
A
Spherical
11
Q
What shape are p-orbitals?
A
Dumb - bell shaped
12
Q
Why is the first ionisation energy always endothermic?
A
energy is required to break the attraction between the nucleus and outermost electron
13
Q
What are the three types of subshell or orbital?
A
S - P - d
14
Q
How many electrons can fit in a subshell or orbital?
A
2
15
Q
How many electrons can fit in the first energy level or shell?
A
2
16
Q
How many electrons can fit in the second energy level or shell?
A
8
17
Q
How many electrons can fit in the third energy level or shell?
A
18
18
Q
How many s-orbitals are there in each energy level?
A
1
19
Q
How many p-orbitals are there in the second and third energy level?
A
3 - each
20
Q
How many d-orbitals are there in the third energy level?
A
1
21
Q
How is the spin of two electrons in an orbital related? Why?
A
Opposite, to minimise repulsion
22
Q
Why do electrons fill orbitals singly first, before pairing up?
A
To minimise repulsion
23
Q
What is a ‘delocalised’ electron?
A
An electron that can move
24
Q
What is a lattice?
A
regular, repeating, 3D structure
25
Define ‘metallic bonding’
the electrostatic attraction between positive ions and delocalised electrons
26
Why are metals good conductors of heat?
their delocalised electrons move around and pass on energy whenever they collide with another electron or positive ion in the lattice
27
Why are metals good conductors of electricity?
delocalised electrons can move and carry charge through the structure
28
Why do metals have high melting points?
the electrostatic attraction between positive ions and delocalised electrons is strong
29
Why are metals malleable and ductile?
the electrostatic attraction between positive ions and delocalised electrons hold the layers together, but the regularity of the layers means they can slide over each other
30
What does ‘malleable’ mean?
can be hammered into shape
31
What does ‘ductile’ mean?
can be stretched into wires
32
Where do we find the atomic number of an element?
periodic table - bottom number
33
Where do we find the relative atomic mass of an element?
periodic table - top number
34
How do we calculate the relative formula mass of a substance?
add together the mass of all atoms present
35
What is a mole?
23
6.02 x 10 particles
36
What is a mole?
23
6.02 x 10 particles
37
What is the equation for converting between mass and moles?
moles = mass / Mr
38
What does the atomic number tell us?
the number of protons in the nucleus
39
How do we know how many electrons an atom has?
atoms have the same number of protons and electrons
40
How do we know how many neutrons an atom has?
subtract the atomic number from the mass number
41
What is the molar mass of a substance?
The mass in grams of one mole (in g/mol)
42
What is the molarity of a substance?
The number of moles of the substance dissolved in 1 dm3 of water (mol dm-3)
43
What is the equation linking concentration and moles?
Concentration = moles / volume
44
What is the equation linking mass and concentration
Concentration = mass / volume
45
How are elements arranged in the periodic table?
In order of increasing atomic number
46
What are the columns called on the periodic table?
Groups
47
What are the rows called on the periodic table?
Periods
48
Where are metals and non-metals on the periodic table?
Metals on the left, non-metals on the right
49
What links elements in the same group?
Same number of electrons in the outer shell
50
What links elements in the same period?
Same number of electron shells
51
What is a periodic trend?
One that follows the same pattern in every period
52
What is the s-block?
The elements that have their outermost electron in an s-orbital (groups 1 and 2)
53
What is the p-block?
The elements that have their outermost electron in an p-orbital (groups 3-8)
54
What is the d-block?
The elements that have their outermost electron in an d-orbital (between the s- and p-blocks)
55
How does ionisation energy vary in a group?
Decreases going down the group
56
How does ionisation energy vary across a period?
Increases, but with anomalies in groups 3 and 6
57
What causes the anomalous ionisation energy in group 3?
The third electon is in a p-subshell, slightly further from the nucleus
58
What causes the anomalous ionisation energy in group 6?
The sixth electron goes in an occupied orbital, so experiences spin-pair repulsion
59
What is electron affinity?
The energy released when 1 mole of gaseous atoms gain one mole of electrons
60
What is electron affinity?
The energy released when 1 mole of gaseous atoms gain one mole of electrons
61
Why is the first electron affinity exothermic?
Energy is released when an electron is attracted to a nucleus
62
Why are all electron affinities apart from the first endothermic?
Energy is required to add a negative electron to a negative ion (due to repulsion)
63
What is the atomic radius?
The distance from the nucleus to the outermost electron
64
How does atomic radius vary across a period?
Decreases
65
How does atomic radius vary down a group?
Increases
66
What factors affect atomic radius?
Nuclear charge, shielding, nuclear attraction
67
When is ionic bonding most likely to occur?
when a metal and non-metal react together
68
what charge do metal ions have?
a positive charge with the number corresponding to their group
69
what charge do non-metal ions have?
a negative charge with the number corresponding to 8-(their group number)
70
what charge do non-metal ions have?
a negative charge with the number corresponding to 8-(their group number)
71
what are the proprties of ionic compounds?
high melting and boiling points; soluble in water; conduct electricity when molten or aqueous
72
why do ionic compounds have high melting and boiling points?
a lot of energy is required to break the many strong electrostatic attractions between oppositely charged ions
73
why are ionic compounds soluble in water?
their charged ions can interact with water molecules
74
why do ionic compounds conduct electricity when molten or aqueous?
because in these states their ions are free to move and carry a charge through the structure
75
what is ionic bonding?
the strong electrostatic attraction between oppositely charged ions that act in all directions
76
what affects the strength of ionic bonding?
smaller, more highly charged ions form stronger bonds
77
how does ionic radius change in a group?
increases down the group as there are more energy levels
78
when is covalent bonding most likely to occur?
between non-metal atoms
79
what is a covalent bond?
a shared pair of electrons
80
what is covalent bonding?
the strong electrostatic attraction between two nuclei and a shared pair of electrons between them?
81
what is a giant covalent structure?
a lattice of many atoms bonded covalently
82
what is a dative covalent bond?
a covalent bond in which the pair of electrons being shared is donated by one atom
83
what is the relationship between bons length and bond strength?
shorter bonds are stronger
84
how do multiple bonds affect bond length?
multiple bonds are shorter
85
what shape are most organic molecules?
tetrahedral
86
what is the bond angle in a tetrahedral molecule?
109.5
87
why do tetrahedral molecules form a specific shape?
the four pairs of electrons repel each other to the position of minimum repulsion
88
what are the three types of imtermolecular force?
van der Waals, hydrogen bonds, permanent dipole - dipole
89
what type of substance can form van der waals forces?
anything, but mainly simple atoms and molecules
90
what affects the strength of van der waals forces?
more electrons = stronger forces
91
what types of dipole are invloved in van der waals forces?
induced and instantaneous
92
what causes an instantaneous dipole
an uneven distribution of electrons
93
what causes an induced dipole
close approach of another dipole
94
what causes a permanent dipole?
a difference in electronegativity between two atoms in a bond
95
what type of molecule has a permanent dipole?
a polar molecule
96
which bonds are needed for hydrogen bonding to occur?
O-H; N-H; F-H
97
why do only certain bonds form hyrdogen bonds?
they have to have a big difference in electronegativity and both atoms must be very small
98
what is important about hydrogen bonding?
it is the strongest type of intermolecular force
99
what is the formula of a hydroxide ion?
OH-
100
what is the formula of a sulfate ion?
SO42-
101
what is the formula of a carbonate ion?
CO32-
102
what is the formula of a nitrate ion?
NO3-
103
what is the formula of an ammonium ion?
NH4+
104
what is relative atomic mass?
the mean mass of the isotopes of an element compared to 1/12 of the mass of a carbon-12 atom
105
what is electronegativity?
a measure of the tendency of an atom to attract a bonding pair of electrons in a covalent bond
106
how do metals react with oxygen?
they form ionic basic oxides e.g. magneisum oxide
107
how do non-metals react with oxuygen?
they form covalent acidic oxides, e.g. carbon dioxide
108
why does incomplete combustion occur?
if there is not enough oxygen
109
what are possible products of incomplete combustion?
carbon, carbon monoxide, water
110
what do metals form when they react with water?
metal hydroxides and hydrogen
111
what does magnesium form when it reacts with steam?
magnesium oxide and hydrogen
112
what do metals form when they react with acids?
Salts
113
what do metals form when they react with sulfuric acid?
metal sulfates and hydrogen
114
what do metals form when they react with hydrochloric acid?
metal chlorides and hydrogen
115
what is oxidation?
gaining oxygen, losing hydrogen, or losing electrons
116
what is reduction?
losing oxygen, gaining hydrogen, or gaining electrons
117
what is a redox reaction?
a reaction where something is oxidised and another thing reduced
118
What is the rule for a displacement reaction?
a more reactive element will displace a less reactive element from a compound
