1.1 Atomic Structure Flashcards
What is atomic mass?
Number of protons in an atom (and therefore also electrons)
What is mass number?
Total number of protons and neutrons
What are isotopes?
Isotopes are atoms with the same number of protons but different numbers of neutrons, and therefore a different mass number
Name the stages of the mass spectrometer
Ionisation, acceleration, ion drift (in the flight tube), detection, data analysis
What must you account for when calculating the relative atomic mass from mass spectra?
The relative abundances of isotopes
How many electrons does each atomic orbitals hold?
s holds 2, p holds 6, d holds 10
Name the sub atomic particles which make up an atom
Proton, electron,neutron
What is ionisation energy?
The energy needed to remove one mole of electrons from one mole of atoms in a gaseous state
What is the general trend in ionisation energy across a period?
General increase alone a period due to increasing nuclear charge
What are the relative masses and charges of the sub atomic particles?
Neutron: 1, 0 Proton, 1, +1 Electron, 1/1840, -1
What holds electrons and protons together in an atom?
Electrostatic forces of attraction
How do you calculate the mass number?
number of protons + number of neutrons (the total number of nucleons)
Define the term relative atomic mass
The average mass of an atom compared to the mass of 1/12 of a carbon 12 atom
Explain why a time of flight mass spectrometer is kept under a vacuum
To prevent the ions that are produced colliding with molecules from the air
What causes the ions to accelerate through a mass spectrometer?
They are attracted by a negatively charged plate
Give the electronic configuration, showing all the sub levels, of a calcium atom
1s2 2s2 2p6 3s2 3p6 4s2
What is the relative mass of an electron?
1/1840
What is meant by the term first ionisation energy?
The enthalpy change needed to move an electron from the outer most shell of an atom
Why does the first ionisation energy generally decrease as you go down a group?
Down a group there is more electron shielding because there are increasing numbers of electron shells. Therefore the outer electrons are further from the nucleus and thus easier to remove.
Why does the first ionisation energy generally increase as you go across a period?
As you move across a period, the atomic radius decreases. This means the outer electrons are closer to the nucleus and more strongly attracted to the center. Therefore, it becomes more difficult to remove the outermost electron.
What holds electrons and protons together in an atom?
Electrostatic forces of attraction
How do you calculate the mass number?
number of protons + number of neutrons (the total number of nucleons)
Define the term relative atomic mass
The average mass of an atom compared to the mass of 1/12 of a carbon 12 atom
Explain why a time of flight mass spectrometer is kept under a vacuum
To prevent the ions that are produced colliding with molecules from the air
What causes the ions to accelerate through a mass spectrometer?
They are attracted by a negatively charged plate
Give the electronic configuration, showing all the sub levels, of a calcium atom
1s2 2s2 2p6 3s2 3p6 4s2
What is the relative mass of an electron?
1/1840
What is meant by the term first ionisation energy?
The enthalpy change needed to move an electron from the outer most shell of an atom
Why does the first ionisation energy generally decrease as you go down a group?
Down a group there is more electron shielding because there are increasing numbers of electron shells. Therefore the outer electrons are further from the nucleus and thus easier to remove.
Why does the first ionisation energy generally increase as you go across a period?
As you move across a period, the atomic radius decreases. This means the outer electrons are closer to the nucleus and more strongly attracted to the center. Therefore, it becomes more difficult to remove the outermost electron.
