3.1.1 Atomic Structure Flashcards
3.1.1.1 Fundamental particles 3.1.1.2 Mass number and isotopes 3.1.1.3 Electron configuration
What are the charges of protons?
Positively charged
+1
What are the charges of electrons?
Negatively charged
-1
What are the charges of neutrons?
No charge
0
Why do atoms have no overall charge?
Atoms have an equal number of protons and electrons so have no overall charge
What is the atomic number of an atom?
The number of protons in an atom
What is the atomic mass of an atom?
The number of protons and neutrons
Why is the relative atomic mass sometimes a decimal in the periodic table?
It is the average atomic mass of different isotopes of the same element
What is the formula to work out relative atomic mass?
Relative atomic mass = ((n1mass)+(n2mass)+(n3*mass))/ n1 +n2+n3
What does m/z stand for?
Mass of ion divided by charge number of ion
What is time of flight mass spectrometry?
Mass spectrometry is a very powerful instrumental technique used to accurately find the relative mass of elements and compounds
What is the first stage of time of flight mass spectrometry called?
Ionisation
What is electron impact in stage 1 (Ionisation) of time of flight mass spectrometry used for?
Electron impact is used for elements and low mass compounds (low Mr compounds)
What occurs in electron impact in stage 1 (Ionisation) of time of flight mass spectrometry?
- High energy electrons fired by electron gun at gaseous sample
- Causes atom/molecule to lose an electron
- Atom/molecule forms a positive ion
X(g) - X+(g) + e-
What is electrospray ionisation in stage 1 (Ionisation) of time of flight mass spectrometry used for?
Electrospray ionisation is used for high mass compounds (high Mr compounds) e.g. proteins
What occurs in electrospray ionisation in stage 1 (Ionisation) of time of flight mass spectrometry?
- Sample dissolved in volatile solvent
- Injected from a a fine hypodermic needle as a fine spray into a vacuum in ionisation chamber
- High voltage applied to end of needle so positively charged where spray emerges
- Particles ionised, gaining a proton from the solvent when leaving the needle
- Solvent evaporates leaving positive ions
X(g) + H+ - XH+(g)
What is the purpose of stage 1 (Ionisation) of time of flight mass spectrometry?
- For the sample to become a positively charged ion
- Only ions will be accelerated by electric field
- Only ions create a current
What is the second stage of time of flight mass spectrometry called?
Acceleration of ions
What occurs in stage 2 (Acceleration of ions) of time of flight mass spectrometry?
- Ions are accelerated using an electric field so all ions have the same kinetic energy
KE = 1/2 mvv
Kinetic energy = 1/2* mass of particle * velocity of the particle (squared)
J KG ms-1
What is the third stage of time of flight mass spectrometry called?
Flight tube/Ion drift
What occurs in stage 3 (Ion drift) of time of flight mass spectrometry?
- The ions enter the flight tube with same kinetic energy
- Ions with different masses have a different time of flight
- The lighter ions travel faster and take less time to reach the detector
t=d√m/2KE
time of flight = length of flight tube *(√(mass of particle/2Kinetic Energy))
s m kg J
t=d/v
time of flight = length of the flight tube/ velocty of the particle
s m ms-1
What is the fourth stage of time of flight mass spectrometry called?
Detection
What occurs in stage 4 (Detection) of time of flight mass spectrometry?
- Detector is a negatively charged plate
- Positive ions hit the negative plate producing a current
- The more ions hit the detector, the bigger the current
- The mass of the ions hitting the detector can be calculated from the time of flight
- The mass spectrum shows the number of particles (abundance) of each mass that hit the detector
What is the electronic configuration of Hydrogen? 1 (H)
1s1
What is the electronic configuration of Helium? 2 (He)
1s2
What is the electronic configuration of Lithium? 3 (Li)
1s2 2s1
What is the electronic configuration of Berylium?4 (Be)
1s22s2
What is the electronic configuration of Boron? 5 (B)
1s2 2s2 2p1
What is the electronic configuration of Fluorine? 9 (F)
1s2 2s2 2p5
What is the electronic configuration of Neon? 10 (N)
1s2 2s2 2s6
What is the electronic configuration of Sodium? 11 (Na)
1s2 2s2 2p6 3s1
What is the electronic configuration of Aluminium? 13 (Al)
1s2 2s2 2p6 3s2 3p1
What is the electronic configuration of Calcium? 20 (Ca)
1s2 2s2 2s6 3s2 3p6 4s2
What is the electronic configuration of Scandium? 21 (Sc)
2s2 2s2 2p6 3s2 3p6 4s2 3d1
What is the electronic configuration of Titanium? 22 (Ti)?
1s2 2s2 2p6 3s2 3p6 4s2 3d2
What is the electronic configuration of Vanadium? 23 (V)
1s2 2s2 2p6 3s2 3p6 4s2 3d3
What is the electronic configuration of Chromium? 24 (Cr)
1s2 2s2 2p6 3s2 3p6 4s1 3d5
What is the electronic configuration of Nickel? 28 (Ni)
1s2 2s2 2p6 3s2 3p6 4s2 3d8
What is the electronic configuration of Copper? 29 (Cu)
1s2 2s2 2p6 3s2 3p6 4s1 3d10
What is the electronic configuration of Zinc? 30 (Zn)
1s2 2s2 2p6 3s2 3p6 4s2 3d10
What is the electronic configuration of Galium? (Ga)
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1
What is the electronic configuration of Yttrium? 39 (Y)
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d1
What is the electronic configuration of Molybdenum? 42 (Mo)
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d5
What are rows in the periodic table called?
Periods
What are the places where electrons are held called?
Energy levels/orbital
In electronic configuration, what does the s represent?
s is an energy level which can hold a maximum of 2 electrons (Group 1, Group 2)
In electronic configuration, what does p represent?
p is an energy level/orbital which can contain a maximum of 6 electrons (Groups 3-8)
In electronic configuration, what does d represent?
d is a energy level which can contain a maximum of 10 electrons (transition metals)
In electron configuration, what does the first number represent?
The period (exception of transition metals which are 1 less)
In electronic configuration, what does the second (smaller) number represent?
The number of electrons (total smaller numbers should be the atomic number of the atom)
In period 4, which elements differ to the pattern and why?
Chromium (Cr)1s2 2s2 2p6 3s2 3p6 4s1 3d5 The 4s energy level and the 3d energy level are half full of electrons Copper (Cu) 1s2 2s2 2p6 3s2 3p6 4s1 3d10 The 4s energy level only contains 1 electron whereas the 3d energy level is full
What does Isoelectronic mean?
Isoelectronic is when different ions have the same electronic configuration
What is the electronic configuration for the ion Li+?
Li atom - 1s2 2s1 Li+ ion - 1s2
What is the electronic configuration for N3- ion?
N atom - 1s2 2s2 2p3 N3- ion - 1s2 2s2 2p6
What charge do metals have when becoming ions?
All metals form positive ions
In period 4, what part of the electronic configuration do transition metals lose when becoming an ion?
Transition metals in period 4 lose the 4s2 electrons before the 3d electrons
Do transition metals form full outer energy levels?
Transition metals do not form full outer energy levels
Why do isotopes have identical chemical properties?
- Same number of electrons/ electronic configuration
- Chemical reactions depend on electrons
Why do Group 1-Alkali metals become more reactive the further down the periodic table?
- Electron further away from nucleus
- More shielding of the nucleus
- Weaker forces of attraction
- More likely to lose ion with more energy levels
What is ionisation?
Ionisation is the removal of an electron
What is 1st ionisation energy?
The energy needed to remove one mole of electrons from one mole of atoms
- to break forces of attraction between nucleus and proton
What does the amount of energy needed for ionisation to occur depend on in periods?
- More protons
- Energy level/distance (shielding of the nucleus)
- Forces of attraction
From Group 1 to Group 2, how does ionisation energy change?
Increases:
- More protons
- Same s subshell (energy level)
- Stronger forces of attraction
- Stronger attraction for electron(s) in outer shell
From Group 2 to Group 3, how does ionisation energy change?
Decreases:
- New p subshell (energy level), more shielding
- Further away
- Weaker forces of attraction
From Group 3 to Group 5, how does ionisation energy change?
Increases:
- More protons
- Same p subshell (energy level)
- Stronger forces of attraction
- Stronger attraction for electron(s) in outer shell
From Group 5 to Group 6, how does ionisation energy change?
Decreases:
- Electron pair repulsion
- 2 pairs of electrons in energy level
- Less energy required as it already repels
From Group 6 to Group 8, how does ionisation energy change?
Increases:
- More protons
- Same p subshell (energy level)
- Stronger forces of attraction
- Stronger attraction for electron(s) in outer shell
How does the 2nd ionisation energy differ from the 1st ionisation energy?
More energy needed:
- Ion positive charge
- Stronger electrostatic forces of attraction
What does the energy increase in successive ionisation energy depend on?
- Charge of the ion
- Orbital it is removed from
How does successive ionisation help find which group an element is from?
- A huge difference in energy is the change from 1 energy level (orbital) to another therefore the number of electrons removed is the group the element is from
What type of reaction is ionisation?
Ionisation energy is an endothermic reaction
Why is ionisation energy endothermic?
Takes in energy to break forces of attraction between the positive nucleus and negative electron (opposite forces attract)
Which fundamental particle would not be deflected by an electric field?
A neutron
What are the 3 blocks in the periodic table?
- s block
- d block
- p block
Which has a higher energy level, 3p or 3s?
3p has a higher energy level than s
Why are Group 4 transition metals placed in block d?
Their highest energy is in block 3d
What is first ionisation of an atom?
The energy required for an electron to be removed from a gaseous atom
What is atomic radius?
The distance from the nucleus to the outer energy level with electron(s)
How does atomic radius change going down a periodic table?
Atomic radius increases down the periodic table (columns)
How does atomic radius change going along the periodic table?
Atomic radius decreases along the periodic table (rows)
Why is it surprising when Noble Gas’ react?
Noble Gas’ are inert gases which have a stable electronic configuration