1.1 Atomic Structure Definitions

Question 1

Define Acceleration

Answer 1

Second stage of TOF spectrometry. The positively charged ions are accelerated by an electric field so that they have the same kinetic energy.

Question 2

Define Atom

Answer 2

The smallest part of an element that can exist. All substances are made up of atoms

Question 3

Define Atomic nucleus

Answer 3

Positively charged object composed of protons and neutrons at the centre of every atom with one or more electrons orbiting it

Question 4

Define Atomic number

Answer 4

The number of protons in the nucleus

Question 5

Define Electron

Answer 5

Negatively charged subatomic particle which orbit the nucleus at various levels. Relative mass of 1/2000

Question 6

Define Electron configuration

Answer 6

The distribution of electrons of an atom in orbitals. E.g

Cu : 1s22s22p63s23p64s13d10

Question 7

Define Electronspray ionisation

Answer 7

Method of ionisation in TOF spectrometry. The sample is dissolved and pushed through a fine nozzle at a high pressure. A high voltage is applied to it causing each particle to gain an H+ ion. The sample is then turned into a gas

Question 8

Define Election impact ionisation

Answer 8

Method of ionisation in TOF spectrometry. The sample is vaporised and an electron gun fires high energy electrons at it, causing an electron to be knocked off each particle to produce 1+ ions.

Question 9

Define First ionisation energy

Answer 9

The energy required to remove 1 mole of electrons from 1 moles of gaseous atoms to form 1 mole of gaseous 1+ ions e.g O(g) —> O+(g) + e-

Question 10

Define Ion Detection

Answer 10

Fourth stage of TOF spectrometry. The negatively charged plate detects charged particles and a mass spectrum is produced.

Question 11

Define Ion drift

Answer 11

Third stage of TOF spectrometry. The ions enter a region with no electric field, so they drift through it. The lighter the ion, the faster they will drift

Question 12

Define Ionisation

Answer 12

First stage of TOF spectrometry. The sample can be ionised by electrospray ionisation or electron impact ionisation

Question 13

Define Isotope

Answer 13

Atoms of the same element with the same number of protons but a different number of neutrons e.g. 35Cl and 37Cl

Question 14

Define Mass number

Answer 14

The total number of protons and neutrons in the nucleus

Question 15

Define Mass spectrometer

Answer 15

A mass spectrometer give accurate information about relative isotopic mass and also about the relative abundance of isotopes

Question 16

Define Mass spectrometry

Answer 16

Mass spectrometry can be used to identify elements and determine relative molecular mass.

Question 17

Define Neutron

Answer 17

Neutral subatomic particle present in the nucleus of an atom. Relative mass of 1

Question 18

Define Nuclear Charge

Answer 18

Total charge of all the protons in the nucleus. It has the same value as the atomic number. Increases as you go across the periodic table

Question 19

Define Proton

Answer 19

Positively charged subatomic particle present in the nucleus of the atom. Relative mass of 1

Question 20

Define second ionisation energy

Answer 20

The energy required to remove 1 mole of electrons from 1 moles of gaseous 1+ ions to form 1 moles of gaseous 2+ ions. E.g. O+(g) —> O2+(g) + e-

Question 21

Define sub-shells (orbitals)

Answer 21

Electron shells are divided up into subshells which have slightly different energy levels. The sub-shells have different numbers of orbitals which can each hold up to two electrons. Types of sub-shell: s,p,d and f

Question 22

Define Time of Flight (TOF) spectrometry

Answer 22

A method of mass spectrometry where an ions mass-to-charge ratio is determined by a time of flight measurement. Consists of four stages: ionisation, acceleration, ion drift and detection.