Atomic Structure (Chapter 1) CHEMISTRY
Why do we assume that there are the same number of protons and electrons in an atom?
Because atoms like to be electronically neutral.
a) How many protons, neutrons and electrons does deuterium have?
b) How many protons, neutrons and electrons does tritium have?
a) 1 proton, 1 neutron, 1 electron
b) 22 protons, 22 neutrons, 26 electrons
Define 'isotope'
Two atoms with the same number of protons but a different number of neutrons
What is the formula for relative atomic/molecular mass?
average mass of molelcule/1 atom\1/12 mass of 1 atom of 12C
What occurs in a Time Of Flight spectrometer? (7 points)
- Vacuum
- Ionisation
- Electron impact
- Acceleration
- Ion drift
- Detection
- Data analysis
Describe the changing ideas of the structure of the atom from Dalton to Schrodinger
DALTON -> Atoms were simply balls of energy that could not be divided
RUTHERFORD -> Found that most of the mass and all the positive charge of the atom was in the nucleus
BOHR -> Atoms consist of a positively charged nucleus orbited by electrons
SCHRODINGER -> Electrons have some of the same properties of waves and particles
Draw the s-orbital and the three p-orbitals
Look up image
What is the max. number of electrons that a single atomic orbital can hold?
Two
How many s-orbitals are in:
a) Sub-level 1
b) Sub-level 2
c) Sub-level 3
a) 1
b) 2
c) 3
How many p-orbitals are in:
a) Sub-level 1
b) Sub-level 2
c) Sub-level 3
a) 0
b) 3
c) 3
How many d-orbitals are in:
a) Sub-level 1
b) Sub-level 2
c) Sub-level 3
a) 0
b) 0
c) 5
True or false: Two electrons in the same atomic orbital may have the same spin
False. Two electrons in any atomic orbital must have opposite spins
What are the three rules for allocating electrons to atomic orbitals?
1) Atomic orbitals of lower energy are filled first
2) Atomic orbitals of the same energy fill singly before pairing starts
3) No atomic orbital can hold more than two electrons
Give the full electron arrangement for phosphorus
3s² 3p³
a) Give the full electron arrangements of:
i) Ca2+
ii) F-
b) Give their electron arrangements using an inert gas symbol as a shorthand
a) i) 4s²
ii) 2s² 2p⁵
b) i) 1s2 2s2 2p6 3s2 3p6
ii)1s2 2s2 2p5
What is the trend in ionisation energies across a period?
IEs generally increase across a period because the nuclear charge is increasing and this makes it more difficult to remove an electron.
What is the trend for ionisation energies down a group?
Ionization energy decreases down a group because the outer electrons are further away from the nucleus.
What is a vacuum used for in a TOF spectrometer?
Prevents the ions that are produced from colliding with molecules from the air
What is ionisation?
A technique used to produced ions using an electrospray in which a large voltage applied to a liquid to create an aerosol.
What is electron impact?
Sample is vaporised and high energy electrons are fired at it from an electron gun, which is a hot wire filament with a current running through it that emits a beam of high energy electrons
What is acceleration?
Positive ions are attracted towards a negatively charged plate and accelerate towards it. Lighter/more highly charged molecules accelerate faster.
What is ion drift?
Ions pass through a hole in the negatively chared plate, forming a beam and travelling along the flight tube to a detector
What is detection?
When ions of the same charge arrive at the detector, the lighter ones have higher velocities. The flight time is recorded. The positive ions pick up an electron from the detector, which causes a current to flow.
What is data analysis?
The signal from the detector is passed to a computer which generates a mass spectrum.
What is the formula for the number of electrons per energy level?
2n2 (n being the energy level number(i.e. first level is 2(1)2))
What is the electron configuration for EL 1?
1s2
What is the electron configuration for EL 2?
1s2 3p6
What is the electron configuration for EL 3?
1s2 3p6 5d10
What is the electron configuration for EL 4?
1s2 3p6 5d10 7df14
What are sub-levels?
Levels inside an energy level- they can hold a maximum of two electrons each and are denoted by the letters: s,p,d,f
Briefly describe the structure of:
a) s-orbitals
b) p-orbitals
c) d-orbitals
a)
- Max of two electrons
- 1 s-orbital per energy level
b)
- Max of two electrons
- 3 p-orbitals per energy level
c)
- Max of two electrons
- 5 d-orbitals per energy level