3.1.1 Periodicity Flashcards
Elements in two periods show a repeating pattern in chemical and physical properties. What is the name given to this repeating pattern of properties
Periodicity
Explain why the first ionisation energy of strontium is less than the first ionisation energy of calcium
Strontium has more shells, increased shielding so less nuclear pull
The first ionisation edgy of magnesium’s is higher than aliumuin give details into its electron structure using this fact
Mg must have an outer electron in the s sub shell
Al has an outer electron is p sub shell so easier to remove
Why do successive ionisation energies increase with ionisation number ?
Nuclear pull increases
Radius increases
Define what is meant by ionisation energy
The minimum amount of energy required to remove 1 mol of electrons from 1 mole of atoms in a gaseous state
What three factors affect ionisation energies ?
Nucelar Charge
Electron Sheilding
Atomic Radius
How does 1st ionisation energies change down a group and why ?
DECREASES
More electron shielding as more electron shells meaning larger distance between nucleus and outer shell = weaker force of attraction, atomic radius increasing = outer electron is further from nucleus decreasing attraction to nucleus
How does 1st ionisation energies change across a period and why ?
INCREASE
Increasing number of protons in the nucleus, increasing nuclear pull, same shell so shielding no effect, overall bigger pull on electron
Explain why there is a decrease in the 1st ionisation energy across period 3 from Mg to Al (concept is also applicable for period 2)
Mg outer electron from 3s subshell
Al outer electron from 3p subshell
3p is higher energy level than 32
Explain why there is a decrease in the 1st ionisation energy across period 3 from P to S (concept is also applicable for period 2)
Due to p orbital electron repulsion as in S one of the 3p orbitals contains 2 electrons therefore they repel each other so less energy required to remove it
Define successive ionisation energies and why it increases with each electron removed
Removal of more than 1 electrons from the same atom
Removing the electron from an increasingly positive ion so more energy required
What determines the order of elements in the periodic table
Number of protons within the nucleus
Which element forms a compound with fluorine that has octahedral molecules and is found in period 3
S8
Estimate the energy required to firn one Li+ g ion from one Li g atom. Give answer in kJ and two significant figures.
500 / 6.02 x 10(23) =19,102.99 8.3 x 10 (-22)
Explain why the first ionisation energies of He and Be are both higher than the first ionisation energies of Li
Explanation of He = smaller atomic radius so increased nuclear pull increased energy needed
Explanation for Be = more protons so increased nuclear pull however same shielding
Explain why the second ionisation energy of Sr is greater than the first ionisation energy of Sr
2nd electron is removed from a positively charged ion as Sr has lost on electron already so greater nuclear pull so more energy needed
