Atomic structure Flashcards
What is the mass and charge on a proton?
1 +1
What is the mass and charge on an electron?
1/2000 -1
What is the mass and charge on a neutron?
1 0
What is the definition of an atom
Atom -the smallest particle of a chemical element that can exist.
What is the definition of an Ion
Ion -an atom or molecule with a net electric charge due to the loss or gain of one or more electrons
What is the definition of an Cation
Cation – a positively charged ion due to the loss of electron(s)
What is the definition of an Anion
Anion – a negatively charged ion due to the gain of electron(s)
What is the definition of an Isotope
Isotope – atoms of the same element that contain the same number of protons but a different number of neutrons.
What is the definition of an Atomic number
Atomic number – the number of protons (or electrons) in an atom.
What is the definition of an Mass number
Mass number – the total number of protons and neutrons in the nucleus of an atom.
What is the definition of an Relative atomic mass
Relative atomic mass – the average mass of an atom of an element relative to 1/12 the mass of an atom of carbon-12.
What is the definition of an Relative isotopic mass
Relative isotopic mass – the mass of a single isotope of an element relative to 1/12 the mass of an atom of carbon-12.
What is the definition of an First ionisation energy
First ionisation energy – the energy needed to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions.
What is electron impact in time of flight mass spec?
The Sample is vaporised and then high energy electrons are fired at it. The high energy electrons come from an ‘electron gun’ which is a hot wire filament with a current running through it that emits electrons. This usually knocks off one electron from each particle forming a 1+ ion.
What is the equation for electron impact TOF?
M(g) + e- -> M+(g) + 2 e-
What is electrospray ionisation in time of flight mass spec?
The The sample is dissolved in a volatile solvent and injected through a fine hypodermic needle to give a fine mist. The tip of the needle is attached to the positive terminal of a high-voltage power supply. The particles are ionised by gaining a proton (i.e. an H+ ion which is simply one proton) from the solvent as they leave the needle producing XH+ ions (ions with a single positive charge and a mass of Mr + 1).
What is the equation for electrospray ionisation in TOF?
M(g) + H+ -> MH+(g)
How can you calculate relative atomic mass?
(Mass of isotope 1 x %) + (Mass of isotope 2 x %) / 100
What is the trend in ionisation energy down a group?
It decreases
Why does ionisation energy change down a group?
It decrease because Atomic radius increases Shielding by inner electrons increases Less energy needed to remove the electron
What is the trend in ionisation energy across a period?
It increases
Why does ionisation energy change across a period?
It generally increases Atomic radius decreases Nuclear charge increases Shielding is the same More energy is needed to remove the electron.
Which groups have difference in the trend for ionisation energy?
Group 3 and 6
Why do group 3 and 6 have differences in ionisation energy?
Lower first ionisation energy than expected for group 3 and 6. Group 3 have s2, p1 arrangement P1 is further from the nucleus s2 electrons increase the shielding so less energy is needed to remove the p1 electron. Group 6 atoms have p4 arrangement – the repulsion of 2 electrons in the same p orbital leads to less energy being required to remove the outer electron.
