Chapter 1 Flashcards
What 3 things make up atoms?
Protons, neutrons and electrons
What charge do electrons have?
-1
What do electrons wizz round the nucleus in?
Orbitals
What takes up most of the volume of the atom?
The orbitals
Where is most of the mass of the atom located?
In the nucleus
What is located in the nucleus?
Protons and neutrons
What is the relative mass of a proton?
1
What is the relative charge of a proton?
+1
What is the relative mass of a neutron?
1
What is the relative charge of a neutron?
0
What is the relative mass of an electron?
0.0005
What does the mass number tell you?
The number of protons and neutrons
What does the atomic number tell you?
The number of protons
What does it tell you if 2 elements have the same atomic number?
They are isotopes of each other
For neutral atoms, what does the number of protons equal?
The number of electrons
What do ions have different numbers of?
Protons and electrons
What is the relative atomic mass?
The weighted mean mass of an element compared to 1/12th of the mass of a carbon-12 atom.
What is the Relative isotopic mass?
The mass of an atom of an isotope compared with 1/12th of the mass of carbon-12.
What is the relative molecular mass?
The average mass of a molecule or formula unit, compared to 1/12th of the mass of carbon-12.
When is the relative molecular mass used?
When referring to simple molecules
When is the relative formula mass used?
For ionic or giant covalent compounds
How can the relative atomic mass be worked out from isotopic abundances?
- Multiply each relative isotopic mass by it % abundance and add up the results
- Divide by 100
What is mass sprectra produced by?
Mass sprectrometers
What are mass spectrometers?
Devices which are used to find out what samples are made up of by measuring the masses of their components
What useful thing can mass sprectrometers show us?
The relative isotopic masses and abundances of different elements.
How do you work out the relative atomic mass from a mass spectrometer graph?
- Multiply each relative isotopic mass by its relative isotopic abundance and add up the results
- Divide the result by the sum of the isotopic abundances
How can mass spectrometry help identify compounds?
The molecular ion peak will tell you the molecular mass of the compound
What are electron shells made up of?
Shells and orbitals
Do shells closer or further away from the nucleus have higher energy levels?
Shells further away from the nucleus
What do subshells contain?
Orbitals
What can 1 orbital hold up to?
2 electrons
How many orbitals does an ‘s’ subshell contain?
1
How many orbitals does an ‘p’ subshell contain?
3
How many orbitals does an ‘d’ subshell contain?
5
How many orbitals does an ‘f’ subshell contain?
7
How many electrons can an ‘s’ subshell contain?
2
How many electrons can an ‘p’ subshell contain?
6
How many electrons can an ‘d’ subshell contain?
10
How many electrons can an ‘f’ subshell contain?
14
What is an orbital?
The bit of space that an electron moves in?
What is ‘spin-pairing’?
When the electrons in each orbital have to spin in opposite directions
What shape are ‘s’ orbitals?
Spherical
What shape are ‘p’ orbitals?
Dumbell shape
What angle are 3 p-orbitals at to each other?
90 degree angles
What subshells do electrons fill up first?
The lowest energy subshells
What is the only exception in the subshell energy trend?
The 4s subshell has less energy than the 3d subshell
What fills up first, the 4s subshell or the 3d subshell?
The 4s subshell
Do electrons fill orbitals singly before they pair up?
Yes
What do the s-block elements have an outer shell electronic configuration of?
S1 or S2
What do the p-block elements have an outer shell electronic configuration of?
S2P1 to S2P6
How do you work out the electronic configuration of an ion?
Write the elctronic configuration of the atom, then add or remove electrons to or from the highest energy subshell
Why do chronium and copper donate one of their 4s electrons to the 3D subshell?
Because they are more stable with a full or half full d-subshell
What is Electromagnetic radiation?
Energy that’s transmitted as waves
What happens to the frequency of the radiation as you go along the Electromagnetic spectrum?
It increases
In ground state, where do atoms have their electrons?
In their lowest possible energy levels
If an atom’s electrons take in energy from their surroundings, what can happen?
The electrons can move to higher energy levels, further from the nucleus
What are electrons said to be at higher energy levels?
More ‘excited’
When electrons drop energy levels, what do they release?
Energy, which has fixed values
What does an emission spectrum show?
The frequencies of light emitted when the electrons drop down energy levels.
Why is the emission spectrum for each element unique?
Because each element has a different electron arrangement, so the frequencies of radiation absorbed and emitted are different
Where is the only place electrons can exist?
In fixed orbits, or shells
What does each quantum shell have a fixed value of?
Energy
When an electron moves between shells, what is emitted or destroyed?
Electromagnetic radiation
As the energy of shells is fixed, what does this mean about the frequency?
It has a fixed value
What is the first ionisation?
The energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions
What is the equation for the 1st ionisation of oxygen?
O –> 0+ + e-
What are the 3 main factors that affect ionisation energy?
Nuclear charge, electron shells, shielding
How does nuclear charge affect ionisation energy?
The more protons, the more positively charged the nucleus is, so the stronger the attraction to the electrons
How does electron shell effect ionisation energy?
Attraction falls off rapidly with distance. An electron in a shell close to a nucleus will be much more strongly attracted to the nucleus than one far away
How does shielding effect ionisation energy?
As the number of electrons between the outer electrons and the nucleus increases, the outer electrons feel less attraction to the nucleus
What does a high ionisation energy mean?
There is a strong attraction between the electron and the nucleus, so more energy is needed to overcome the attraction and remove the electron
What happens to the 1st ionisation energy as you go down a group?
It decreases
Why does the 1st ionisation energy decrease as you go down a group?
- More shielding
- More shells
What is the 2nd ionisation energy?
The energy needed to remove an electron from each ion in 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions.
What is the equation for the 2nd ionisation energy of oxygen?
O+ —> O2+ + e-
What happens to the values of ionisation energies as more electrons are removed?
They increase
Why does the value of the ionisation energies increase as more electrons are removed?
The ion becomes increasingly positive, so there’s less repulsion amongst the remaining electrons
What are the big jumps in successive ionisation energies?
When a new shell is being broken into, as an electron is being removed from a shell close to the nucleus
What happens to the atomic radius as you go across a group?
The atomic radius decreases
What is the general trend for ionisation energy across a period?
Ionisiation energy generally increases across a period
Why does ionisation energy generally increase across a period?
Stronger nuclear attraction due to more protons, and all the electrons are roughly at the same energy level, so there’s little shielding added
Why is there small drops in ionisation energy across a period as you go from group 2 to group 3?
e.g. Aluminium’s outer electron is in a 3p orbital rather than a 3s orbital. The 3p orbital has slightly higher energy than the 3s orbital, so the electron is found further from the nucleus. The 3p orbital has additional shielding from the 3s electrons
What is the drop in ionisation energy from group 5 to 6 across a period due to?
Electron repulsion:
Elements with singly fulled or full subshells are more stable than those with partially filled subshells, so have higher ionisation energies
Why is it easier to remove electrons from shared orbitals?
Because there is repulsion between the 2 electrons in the orbital
For metals, how does melting and boiling points change as you go across a period?
They increase
Why do melting and boiling points increase as you go across a period for metals?
Metallic bonds get stronger because:
- Metals have an increasing number of delocalised electrons
- Metals have decreasing radius
Why do the elements with strong giant covalent lattices have a high melting/boiling point?
They have strong covalent bonds, meaning a lot of energy is required to break them
Why do elements with simple molecular structures have low melting/boiling points?
London forces are weak and easily overcome, so these elements have low melting/boiling points.
Why do the noble gases have the lowest melting/boiling points?
Because they exist as individual atoms, resulting in weak London forces
