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Flashcards in 1 atomic structure Deck (14):


the tiny positively charged centre of an atom composed of protons and neutrons



protons and neutrons - the sub-atomic particles found in the nuclei of atoms


strong nuclear force

the force that holds protons and neutrons together within the nucleus of the atom


electrostatic forces

the forces of attraction and repulsion between electrically charged particles


proton/atomic number Z

the number of protons in the nucleus of an atom


mass number A

the number of protons and neutrons in the nucleus of an atom



atoms with the same number of protons but a different number of neutrons


molecular ion

in mass spec - a molecule of the sample which has been ionised but has not broken up during its flight through the instrument


atomic orbital

a region of space around an atomic nucleus where there is high probability of finding an electron


ionisation energy IE

the energy required to remove a mole of electrons from a mole of isolated gaseous atoms/ions (kJ/mol)


successive ionisation energy

the energy required to remove another mole of electrons from a mole of isolated gaseous atoms/ions


time of flight mass spectrometry (8+6)

-accurate info on isotope Mr and abundance
-identify elements
-determine Mr
-determines the mass of separate atoms/molecules
-used to identify diff isotopes that make up element by detecting indiv ions and their masses
-high res = 5dp, low res = 1dp
-principle: form ions from sample, separate ions according to ratio of charge to mass

"electrospray ionisation"
- substance in sample converted to +ve ions, accelerated to high speeds (depending on their m/z ratio), and arrive at detector.

1. vacuum - whole apparatus kept under high vacuum to prevent ions produced colliding w molecules in air

2. ionisation - sample is dissolved in a volatile solvent, forced through a fine hollow needle that's connected to the +ve terminal of a high voltage supply. produces tiny +vely charged droplets that have lost e- to the +ve charge of the supply. solvent evaporates from droplets into the vacuum and droplets get smaller until they contain no more than a singly +ve ion

3. acceleration (to give all ions constant kinetic energy) - +ve ions attracted towards a -vely charged plate and accelerate towards it. lighter ions and highly charged ions achieve a higher speed

4. ion drift - ions pass through a hole in plate, forming a beam and travel along flight tube, to a detector

5. detection - flight times are recorded and ions pick up an electron from detector, causing a current to flow

6. data analysis - signal from detector passed to a computer which generates a mass spectrum


s orbital



p orbital