Atomic Structure Flashcards
1
Q
What is an atom?
A
The smallest part of an element that can take place in chemical reactions
2
Q
What is an atom composed of?
A
Empty space around a very small, dense nucleus
3
Q
What particles are found in the nucleus of an atom?
A
Protons and neutrons
4
Q
What is the overall charge of the nucleus?
A
Positive charge
5
Q
What type of charge do protons have?
A
Positive charge
6
Q
What is the charge of neutrons?
A
Neutral charge
7
Q
Where are negatively charged electrons found?
A
In orbitals in the empty space around the nucleus
8
Q
What are the particles that make up an atom called?
A
Subatomic particles
9
Q
List the three main subatomic particles.
A
- Protons
- Neutrons
- Electrons
10
Q
How are the masses and charges of subatomic particles measured?
A
Using relative atomic masses and relative atomic charges
11
Q
What is the relative mass assigned to protons and neutrons?
A
1
12
Q
How much smaller is an electron compared to a proton or neutron?
A
1836 times smaller
13
Q
What is the atomic number also known as?
A
Proton number
14
Q
What does the atomic number (Z) represent?
A
The number of protons in the nucleus of an atom
15
Q
What does the atomic number indicate about a neutral atom?
A
It is equal to the number of electrons present
16
Q
What is the mass number also known as?
A
Nucleon number
17
Q
What does the mass number (A) represent?
A
The total number of protons and neutrons in the nucleus of an atom
18
Q
How can you calculate the number of neutrons in an atom?
A
Number of neutrons = mass number - atomic number
19
Q
What are protons and neutrons collectively called?
A
Nucleons
20
Q
Where is the mass of an atom concentrated?
A
In the nucleus
21
Q
What is the charge of the nucleus of an atom?
A
Positively charged
22
Q
What contributes very little to the overall mass of an atom?
A
Electrons
23
Q
What holds an atom together?
A
Electrostatic attraction
24
Q
What is electrostatic attraction?
A
This attraction is between the positive nucleus and negatively charged electrons.
25
What defines an atom as neutral?
It has no overall charge
26
Why does an atom have no overall charge?
Same number of protons and electrons
27
What are ions?
Charged atoms formed by gaining or losing electrons
28
What determines the element of an atom or ion?
Atomic (proton) number
29
How can you calculate the number of protons in an unknown element?
Mass number - number of neutrons
30
What is an isotope?
Atoms of the same element with different numbers of neutrons
31
How are isotopes represented symbolically?
Chemical symbol followed by a dash and the mass number
32
What properties do isotopes of the same element have in common? Why?
Same chemical properties because they have the same number of electrons in outer shell
33
What is the only difference between isotopes?
Number of neutrons
34
How is the mass of an element expressed?
Relative atomic mass (Ar)
35
How can the relative atomic mass of an element be calculated?
Multiply mass of each isotope by its abundance, add results, divide by 100
36
What has happened to a positively charged ion?
It has lost electrons
37
What has happened to a negatively charged ion?
It has gained electrons
38
What do isotopes of the same element display? Why?
Same chemical characteristics - determined by their electron configuration
39
What is Mass Spectrometry?
A powerful analytical technique for determining the relative atomic mass of an element based on isotopes and their abundance.
40
What does a mass spectrometer produce?
A spectrum of mass/charge ratio against abundance.
41
What is the molecular ion peak in mass spectrometry?
The peak with the highest mass, denoted as M+
42
What is the base peak in mass spectrometry?
The peak with the largest abundance, or tallest peak
43
What are the four key stages in time of flight mass spectrometry?
* Ionisation
* Acceleration
* Ion drift
* Detection
44
What is the ionisation method used for elements with lower molecular mass?
Electron Impact
45
What is the process for forming a 1+ ion in Electron Impact ionisation?
X (g) → X+ (g) + e-
46
What is Electrospray Ionisation used for?
Substances with higher molecular mass.
47
Why is electrospray ionisation used for substances with higher molecular mass?
Fragmentation is less likely to occur
48
How is the sample introduced in Electrospray Ionisation?
The sample is dissolved in a volatile solvent and injected using a hypodermic needle.
49
What happens to the sample particles in Electrospray Ionisation?
They gain a proton from the solvent, forming XH+ (g)
The solvent then evaporates, and the ions are accelerated through the mass spectrometer.
50
What is the role of the electric field in the acceleration stage?
To accelerate 1+ ions to have the same kinetic energy
Ensures the velocity of the ions is dependent on their mass
51
What is the significance of the time of flight in mass spectrometry?
Lighter ions move faster than heavier ions.
52
What occurs during the detection stage of mass spectrometry?
1+ ions hit a negatively charged detector plate, gaining an electron and producing a current.
53
What is the current produced in mass spectromery proportional to?
The abundance of the ions.
54
What is the equation for time of flight mass spectrometry?
KE = 1/2 mv²
55
What does KE stand for in KE = 1/2 mv²?
Kinetic Energy
56
What does m stand for in KE = 1/2 mv²?
Mass
57
What does v stand for in KE = 1/2 mv²?
Velocity
58
What is the arrangement of electrons in an atom called?
The electron configuration
59
What happens to the energy and distance from the nucleus as the principle quantum number increases?
The energy increases and the shell is further from the nucleus
60
What is the maximum number of electrons that can be held in the first principal quantum shell (n = 1)?
Up to 2 electrons
61
What is the maximum number of electrons that can be held in the second principal quantum shell (n = 2)?
Up to 8 electrons
62
What are the subshells in the principal quantum shells labeled as?
s, p, d, and f
63
How many orbitals are in the s subshell?
1 orbital
64
What is the maximum number of electrons an s subshell can contain?
2 electrons
65
What is the shape of the s orbitals?
Spherical
66
What is the shape of the p orbitals?
Dumbbell shape
67
What is the ground state of an atom?
The most stable electronic configuration with the lowest amount of energy
68
How is the ground state of an atom achieved?
By filling the lowest energy subshells first.
69
What is the order of subshells in terms of increasing energy?
s < p < d < f
70
What is the maximum number of electrons an f subshell can contain?
14 electrons
71
How many orbitals are there in an f subshell?
7 orbitals
72
What is the maximum number of electrons a p subshell can contain?
6 electrons
73
How many orbitals is there in a p subshell?
3 orbitals
74
What is the maximum number of electrons a d subshell can contain?
10 electrons
75
How many orbitals are in a d subshell?
5 orbitals
76
Where are the s-block elements located on the periodic table?
On the left-hand side
77
Where are the d-block elements located on the periodic table?
The middle
78
Where are the p-block elements located on the periodic table?
On the right-hand side
79
Where are the f-block elements located on the periodic table?
Separate section at bottom
80
Why is the 4s orbital filled before the 3d orbital?
4s is lower in energy
81
What is an ion?
An atom that has lost or gained electrons
82
What is a negatively charged ion known as?
Anion
83
What is a positively charged ion known as?
Cation
84
What does the shorthand electron configuration include?
Using the symbol of the nearest preceding noble gas
85
What is the Ionisation Energy of an element?
The amount of energy required to remove one mole of electrons from one mole of gaseous atoms of an element to form one mole of gaseous ions
86
What conditions are ionisation energies measured under?
Standard conditions
87
What are standard conditions?
298K and 101kPa
88
What are the units of Ionisation Energy?
kilojoules per mole (kj mol-1)
89
What is the first ionisation energy?
The energy required to remove one mole of electrons from one mole of atoms of an element to form one mole of 1+ ions
90
What factors affect ionisation energy?
Size of nuclear charge
Distance of outer electrons from nucleus
Shielding effect of inner electrons
Spin-pair repulsion
91
How does first ionisation energy trend across a period?
Increases
92
How does first ionisation energy trend down a group?
Decreases
93
Why does ionisation energy generally increase across period?
Nuclear charge increases
Atomic radius decreases so distance between nucleus and outer electrons decreases
Shielding remains similar
94
How does ionisation energy differ between last element of one period and first of the next?
Large decrease
95
Why is there a large decrease in ionisation energy between last element of one period and first of the next?
Increased distance between the nucleus and outer electrons as new shell occupied
Increases shielding
Outweigh increased nuclear charge
96
Why does ionisation energy generally decrease down group?
Atomic radius increases
Distance between nucleus and outer electrons increases
Shielding increases
Outweigh increased nuclear charge
97
Why do successive ionisation energies increase?
Once outer electron is removed, a positive ion has formed so removing an electron is more difficult
Attractive forces increase as more electrons removed as decreased shielding and increased proton to electron ratio
