The Atomic Structure Flashcards
What is the mass number?
The number of protons and neutrons added together
What is the atomic number?
The number of protons-also the number of electrons
What are isotopes?
Isotopes are atoms of the same element that have the same number of protons but different number of neutrons
What is common between isotopes?
Isotopes have similar chemical properties because they have the same electronic configuration
What are the different phases of a Time of Flight Mass Spectrometer?
- Ionisation
- Acceleration
- Ion drift
- Detection
What are the two different types of ionisation?
- Electron impact
- Electrospray
What are the steps for the electron impact ionisation?
- A sample is vaporised and is injected at a low pressure
- An electron gun fires high energy electrons at the sample
- An outer electron is knocked out of the sample
- This forms positive ions
What are the steps for the electro spray ionisation?
- The sample is dissolved in a volatile polar solvent.
- The sample is pumped through a hypodermic needle and at the tip, a high voltage is applied
- at the tip of the needle, the sample gains a H+ ion
- The sample is vapourised
What is the electron impact used for?
It is used for elements and substances with low formula mass. This method would cause larger molecules to fragment
What is the electrospray ionisation used for?
It is used for larger molecules and means that they won’t fragment.
What happens in the acceleration phase?
The positive ions are accelerated by an electric field
All the ions are given the same kinetic energy
The velocity of the particles depends on their mass
What happens in the ion drift?
In the ion drift, it is a vacuum and the particles drift along to the detector
The lighter ions travel faster compared to the heavier ions
allows separation of the sample
What happens at the detection?
The detector detects charged ions
the ions gain electrons from the negatively charged plate
The movement of the electrons creates a current
How do you calculate the relative atomic mass(RAM)?
RAM =∑ (isotopic mass*relative abundance)/total relative abundance
What is the current created proportional to?
The abundance of the isotope
What is relative mass?
The average mass of isotopes
How are electrons arranged around the nucleus?
Energy levels
What are energy levels divided up into?
Sub shells
What are the 4 sub shells?
s,p,d,f
What is the maximum number of electrons that each sub shell can contain?
s = 2 p = 6 d = 10 f = 14
Which block are the reactive metals?
S block
Which block are the transition metals?
D block
Which block are group 3 to 0?
P block
How are ions formed?
Ions are formed when atoms lose or gain electrons
What is the definition of isoelectric?
Isoelectric means different elements with the same configuration
What are some examples of isoelectric elements/ions?
N(3-) O(2-) F(-) Ne Na+ Al(3+) Mg(2+)
What happens when transition metals form ions?
they always lose the 4s energy levels before the 3d energy level