Topic 1.1 - Atomic Structure Flashcards
(22 cards)
What is the atomic mass number?
Number of protons plus neutrons found in the nucleus of an atom
What is the atomic number?
Number of protons (equal to the number of electrons)
Define relative atomic mass
The average mass of all isotopes relative to C12 on a scale where C 12 is 12 exactly
What is the formula to calculate relative atomic mass?
Ar = sum (mass of all isotopes x relative abundance) / total relative abundance
What are electron shells made of?
Each shell contains a sub-shell which have different shapes called orbitals.
Electrons in different sub-shells have different amounts of energy
What is the shorthand of an element’s electronic configuration?
[Nobel gas symbol]
What are the two exceptions when it comes to electronic configuration?
- Chromium (1s2 2s2 2p6 3s2 3p6 4s1 3d5)
- Copper (1s2 2s2 2p6 3s2 3p6 4s1 3d10)
How are the chemical properties of an element determined?
Electronic configuration / number of electrons in its outer shell
Define isotope
Atoms of the same element with the same mass number (number of protons) and different atomic number (number of neutrons)
Why do isotopes have the same chemical properties?
They have the same electronic configuration
Define ion
A charged particle formed when an atom loses or gains electrons
When an ion is formed, which electrons are lost first?
Highest energy electrons are lost first as they are found in the outer shell
What metals are an exception when it comes to ions being made (electrons being lost)?
When d-block elements form ions, the electrons in 4s sub-shell are lost first
Why are noble gases inert?
They have completely filled s and p sub-shells. This means they don’t need to lose, gain or share electrons
Define isoelectronic
Ions that have the same electronic configuration
Define first ionisation energy
The energy required to remove one mole of electrons from each atom in one mole of gaseous atoms
What is the reaction for first ionisation energy?
X (g) > X (g) + e-
* elements always need to be a gas
What does a large jump in ionisation energy mean?
Means an electron has been removed from a shell closer to the nucleus
What is the process of mass spectrometry?
1) Ionisation
- Turn atom into ion
- Electron impact
X (g) + e- > X+ (g) + 2e-
Sample is vaporised
Electron is fired and electrons are lost from atom
Same mass after ionisation
Used for small molecules
- Electrospray
X (g) + H+ (g) > XH+ (g)
Atom dissolved in a polar solvent
Put through a small needle at high pressure and high voltage is applied
Fired in many directions into the tube and gains a proton
Mass increase by 1 after ionisation
Used for large atoms
2) Acceleration
- Travels into an electric field
- Ions will have same kinetic energy
- Smaller/ lighter ions = greater acceleration
3) Ion drift
- Ions drift into region with no electric field
- Ions will separate
4) Detector
- Detector is charged
- When ions hit it, it creates an electrical current
- Records how long they took to pass through spectrometer
What is the formula to calculate distance?
Distance (m) = speed (ms-1) x time (s)
What is the formula to calculate kinetic energy?
KE (J) = 0.5 x m (kg) x v2 (ms-1)
How do the relative abundance of an atom determines at detector?
- Ion gains an electron
- The relative abundance depends on the size of current
