Chapter 7 Flashcards
Features of periodic table then
- arranged in order of atomic mass
- lined up groups with similar properties , and if they didn’t fit he would swap elements around to make fit (regardless if mass)
- he would leave gaps for predictions of elements there
What does the period number give
The highest energy electron shell in thst electron atom , if three, then highest energy shell three (three shells)
What does periodicity mean?
For example
A repeating periodic trend ACROSS the periodic table in elements
Such as Electron configuration Ionisation energy Structure Melting points
What is the trend periodicity for electron configuration (2)
What about down a group
- Across a period Esch successive element gains 1 electron
- Across a periodic, the s sub shell and the p sub shell are filled in the same way each time = s periodic trend
- the only difference across each Period is shell number
Down a group , the amount of electrons in each outer shell and type of sun shell is the same
How are elements classified into blocks
The highest energy sub shell where electrons go is where it classified in
What is ionisation energy roughly
Ionisation energy is a skashee ir how easily an atom loses electrons in gaseous state to form positive ions
What is the definition of firdt ionisation energy
Example with Na
First ionisation energy is the energy required to remove one electron from EACH electron in 1 mole of gaseous atoms of an element , to form one mole of gaseous 1+ ions
Na(g) —> Na1+(g) + e-
What three fsctord affect the ionisation energy and how
Ionisation energy depends on the attraction between the nucleus and the outer shell electrons, depending on how string or weak this is determine energy
1) Atomic radius
- increase atomic radius, ionisation energy decreases, as outer electron is further away from nucleus so experiences less attraction = less energy is needed to remove
2) nuclear charge
- increase nuclear charge = increase nuclear attraction = more energy so ionisation energy increases
3) electron shielding
- the greater number of shells = the greater the electron shielding = REDUCES NUCLEAR ATTRATCION = LESS IONISATION ENERGY
Why does electron shielding reduce attraction between outer electron and nucleus?
Increase the shells, means that because electrons negatively charged, they will repel each other, and the more shells, means more repulsion, pushing the outer electron further back and giving less attarction
What happens with successive ionisation energies and why? (Are they bigger smaller same etc)
They are bigger
Removing one electron means that now there are more protons then electrons and so thst electron pulled closer to nucleus and nuclear attraction increases = harder to remove as more energy = ionisation energy increase
What is definition for second ionisation energy
Remember words in middle
Energy required to remove one electron from EACH ION IN 1 mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions of an element
How can you use graph to determine the group element in
- the graph ionisiaiton energies should steadily increase as electrons are removed (remember because attraction increases ).
- however when a BIG jump happens = likely you have moved to the next shell = which is much closer to nucleus so nuclear attraction bigger so explains why bigger energy needed
Count electrons = thats group number
What is the general trend in ionisation energy across a Period and why
Increases
- same shielding due to number of shells
- nuclear charge increases = nuclear attraction increases
- this also pulls on the electrons outer shell which means ATOMIC RADIUS decreases , so less radius also increases attraction
= this means ionisation energy must increase
What is trend in ionisation energy down a group and why
What different what takes priority
Decreases
- shielding increases
- atomic radius increases
- these OUTWEIGH the increased nuclear charge and attraction
Overall attraction decreases = thus ionisation energy decrease
Where are the dips across a period and when
Why do ionisation energy go back to normal after
1) Happens between group 2 and 3
- group 3 is the first element to have an electron in the p sub shell. As the p sub shell is higher energy and FURTHER away, nuclear attraction between electron nucleus decrease, meaning it is easier to lose this electron
2) happens between group 5 and 6
- this is because you are going from an electron in each p orbital to being two electrons of opposite spin in the SAMS ORBITAL, which is more repulsion. This is easier to remove an electron due to more repulsion than version before, so ionisation energy decreased
After you comparing back to previous, + addition of proton negated as nuclear charge just increased
