Topic 2: Atomic Structure Flashcards
What are the sub-atomic particles in an atom?
protons, neutrons and electrons
Where are protons and neutrons located?
In the nucleus
Where are electrons located?
In energy levels within the atom
What is the atomic number?
The number of protons in an atom; the number that gives an atom its identity
How do you find the mass number?
Add protons and neutrons
How do you find the number of neutrons?
Mass number minus protons
Why is the number of protons and electrons the same?
Because atoms are always neutral
What happens in ions?
The number of protons and neutrons remains the same, but the number of electrons changes
What are isotopes defined as?
Atoms of the same element that have the same number of protons, but a different number of neutrons
What is Relative Atomic Mass (RAM) (Ar) defined as?
The average of the masses of the isotopes in a naturally occurring sample of the element, relative to the mass of 1/12 of an atom of C12.
What is a mass spectrometer?
A device used to find the relative mass of elements, isotopes and compounds
How does a mass spectrometer work?
It separates positive ions according to mass/charge ratio. The ions with the lower m/z ratio are deflected more than those with a higher
What does a mass spectrum tell us?
On the X-axis, it shows the mass/charge ratio of different isotopes in an element. On the Y-axis, it shows isotopic abundances
How do you find the RAM of an element from the abundance of its isotopes and their mass/charge ratios?
mass/charge ratio x percent abundance over percent abundance added together
What does the Bohr theory claim?
Each energy level of an atom can hold a certain number of electrons. The main energy level (principal quantum number) is n. The maximum number of electrons in each shell = 2n^2
What are the general rules of the Bohr theory?
- energy levels are filled lowest to highest
- first two levels must be filled before next level
- third is “pseudo filled” at 8, then fourth can be filled
- this works for elements up to 20
What is the electromagnetic spectrum?
The range of wavelengths of electromagnetic radiation
What is the electromagnetic spectrum?
Radio, Microwaves, Infrared, Visible, Ultraviolet, X-Ray, Gamma
Raging Martians Invaded Venus Using X-Ray Guns
Radio, Microwaves, Infrared, Visible, Ultraviolet, X-Ray, Gamma
Which end of the spectrum has lowest energy, longest wavelength?
Radio
Which end of the spectrum has highest energy, shortest wavelength?
Gamma
What is the continuous spectrum?
Shows all wavelengths of VISIBLE LIGHT (ROYGBIV). Energy increases towards violet, wavelength increases towards red
How are line spectra produced?
Electrons transition between energy levels by absorbing or emitting energy.
Electrons absorb energy when transitioning to higher levels.
They emit energy when transitioning to lower levels
How is the absorption line spectrum produced?
When an electron absorbs energy and transitions to higher-level from n=2 level
What colour is produced when an electron transitions from n=2 to n=3 in a hydrogen atom?
Red
What does the Lyman series emit?
UV radiation. Transition to n=1
What does the Balmer series emit?
VISIBLE LIGHT - Transitions to n=2
What does the Paschen series emit?
Infrared radiation - transitions to n=3
What is the order of the sub-levels?
S < P < D < F
How many electrons can there be in one orbital?
2
How many orbitals can S subshells have?
1
How many orbitals can P subshells have?
3
How many orbitals can D subshells have?
5
How many orbitals can F subshells have?
7
Max number of electrons in S?
2
Max number of electrons in P?
6
Max number of electrons in D?
10
Max number of electrons in F?
14
What is Heisenberg’s uncertainty principle?
The velocity and position of an electron cannot be simultaneously measured with high precision
What are orbitals?
Regions where there is a high probability of finding an electron
What shape do S orbitals take?
Spherical
What shape do P orbitals take?
Dumbell
What is the Aufbau principle?
4s comes before 3d because it has lower energy and ELECTRONS PLACED INTO ORBITALS OF LOWER ENERGY FIRST
What is the Pauli exclusion principle?
- no more than 2 electrons per orbital
- must spin in opposite directions
What is Hund’s rule?
Always fill orbitals with one electron first and add a second once each orbital has one electron - empty bus rule
What are the two exceptions?
Chromium and copper, they each give one electron from 4s to 3d
What is a rule for electronic configuration of ions?
4s sub-level loses electrons before 3d does
