1.1 Atomic Structure Flashcards
Draw a table showing the relative mass and charge of a: Neutron, Proton and Electron.
Proton 1,+1
Neutron 1,0
Electron 1/1836,-1
What are ions?
Ions have different numbers of Protons and electrons.
see page 2 in the revision guide for some examples
What are isotopes?
Isotopes are atoms of the same element, the same number of protons with different numbers of Neutrons.
(see page 3 in the revision guide for an example)
What decides the chemical properties of an element?
The number and arrangement of electrons decides the chemical properties of an element.
(see page 9 in the revision guide for my information)
What decides the physical properties of an atom?
The physical properties of an atom tends to depend on the mass of the atom.
Describe how the model of the atomic structure has changed throughout history.
- Dalton described atoms as solid spheres and said different spheres were made up of different electrons 2.Thomson discovered electrons and created the plum pudding model 3. Rutherford’s alpha scattering experiment 4. Bohr’s model of where electrons exist in shells or energy levels.
What is the relative atomic mass?
The relative atomic mass (Ar) is the average mass of an atom of an element on a scale where an atom of carbon-12 is 12.
(see page 5 in the revision guide to see how to calculate this)
What is the relative isotopic mass?
The relative isotopic mass is the mass of an atom of an isotope of an element on a scale where an atom of carbon-12 is 12.
(see page 5 in the revision guide to see how to calculate this)
What is the relative molecular mass?
The relative molecular mass (Mr) is the average mass of a molecule on a scale where an atom of carbon-12 is 12.
(see page 5 in the revision guide to see how to calculate this)
Describe the 4 steps a Mass Spectrometer used to measure mass:charge ratio of an element.
- Ionisation
- Acceleration
- Ion Drift
- Detection
(see page 5 in the revision guide for a description of each)
What is a Mass Spectrum?
A Mass Spectrum is Mass/Charge plotted against abundance.
see page 6 in the revision guide for a diagram and more descriptions
How do you calculate the relative atomic mass of an element from the mass spectrum?
(see page 6 in the revision guide)
How can Mass Spectrometer be used to identify elements?
(see page 6 in the revision guide)
How can Mass Spectrometer be used to identify molecules?
(see page 7 in the revision guide)
What is he number of orbitals and maximum number of electrons in each sub-shell?
S= 1 orbital and 2 electrons P= 3 orbitals and 6 electrons D= 5 orbitals and 10 electrons F= 7 orbitals and 14 electrons
Read the bottom of page 8.
Do you know and understand this section?
How do Chromium (Cr) and Copper’s (Cu) electronic structure behave differently to other elements?
Chromium and Copper only has one electron in it 4s orbital before filling 3d
Cr: 1s²… 3p⁶ 4s¹ 3d⁵
Cu: 1s²…3p⁶ 4s¹ 3d¹⁰
Define the first ionisation energy.
The first ionisation energy is the energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.
Write the equation for the first ionisation energy of oxygen.
O(g) -> O⁺(g) +e⁻
What factors affect ionisation energy?
1) Nuclear charge
2) Distance from the nucleus
3) Shielding
- (see page 10 in the revision guide for details about each)
Define the second ionisation energy.
The second ionisation energy is the energy needed to remove 1 electron from each ion in 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions.
Write an equation for the second ionisation energy of oxygen.
(see page 10 in the revision guide and read it all)
How do successive ionisation energies show shell structure?
(see page 11 in the revision guide)
What happens to the first ionisation energies of elements going down a group?
They decrease.
read page 12 in the revision guide
What happens to the first ionisation energies of elements going across a period?
The generally increase.
read page 12 in the revision guide
Why do isotopes have similar chemical properties?
Because they have the same electronic structure.
Why do isotopes have slightly varying physical properties/
Because they have different masses.
What is a chemical property?
A chemical property is a characteristic or behavior of a substance that may be observed when it undergoes a chemical change or reaction.
What is a physical property?
A characteristic that may be observed and measured without changing the chemical identity of a specimen.
List the four parts to a Time of Flight (TOF) Mass Spectrometer.
- Ionisation
- Acceleration
- Ion drift
- Detection
When is a TOF mass spectrometer used?
The mass spectrometer can be used to determine all the isotopes present in a sample of an element and to therefore identify elements.
Why does TOF mass spectrometry need to be under a vacuum?
Otherwise air particles would ionise and register on the detector.
What two ways can a sample be ionised?
- Electron impact
- Electro spray ionisation
Describe Electron impact.
- A vaporised sample is injected at low pressure
- An electron gun fires high energy electrons at the sample
- This knocks out an outer electron
- Forming positive ions with different charges
E.g. Ti(g) ->Ti+(g) + e-
Describe Electro spray ionisation.
- The sample is dissolved in a volatile, polar solvent
- Injected through a fine hypodermic needle giving a fine mist or aerosol
- The tip of the needle has a high voltage
- At the tip of the needle the sample molecule, M, gains a proton, H+, from the solvent forming MH+
- M(g) + H+ -> MH+(g)
- The solvent evaporates away while the MH+ ions move towards a negative plate.
When is Electron impact used?
For elements and substances with low formula mass. Electron impact can cause larger organic molecules too fragment.
When is Electro spray ionisation used?
Preferably for larger organic molecules. The ‘softer’ conditions of this technique mean fragmentation does not occur.