Module 3 key information Flashcards
How are elements arranged in the periodic table?
Increasing atomic number
What do elements in the same group have in common?
The same number of outer shell electrons
What do elements of the same period have in common?
Same number of highest energy electron shells
What is periodicity?
Repeating trends in chemical and physical properties
What are group 1 metals called?
Alkali metals
What are group2 metals called?
Alkaline earth metals
What are elements in group 3-12 called?
Transition elements
What are elements in group 15 called?
Prictogens
What are elements in group 16 called?
Chalcogens
What are elements in group 17 called?
Halogens
What are elements in group 18 called?
Noble gasses
What is ionisation energy?
How easily an atom loses electrons to form positive ions
What is the definition of first ionisation energy?
The energy required to remove one electron from each atom in 1 mole of gaseous atoms of an element to form one mole of gaseous +1 ions
How can atomic radius affect ionisation energy?
The greater the distance between the outer electrons and the nucleus the fewer nuclear attraction so a decrease in ionisation energy
How does nuclear charge affect ionisation energy?
More protons= greater attraction between the nucleus and outer electrons, increasing ionisation energy
How does electron shielding effect ionisation energy?
Inner electrons repel outer electrons= shielding effect= reduced the amount of attraction between the nucleus and electrons, decreasing ionisation energy
What is the definition of second ionisation energy?
The energy required to remove one electron from each ion in one mole of gaseous +1 ions of an element to form one mole of gaseous +2 ions
Is the second ionisation energy always greater or less than the first ionisation energy?
Greater
How to identify an element from successive ionisation energies?
Large increase between the 3rd and 4th ionisation energies shows that the fourth electron is being taken closer to the nucleus. This means their is 3 electrons in its outer shell so in group three.
Write an equation for the first ionisation energy of magnesium?
Mg(g)——-Mg+(g) + e-
How does ionisation energy change down a group?
1) electron number increases meaning atomic radius increases. Their is less nuclear attraction decreases so the force of attraction is weaker
2) Addition electron shielding from the inncer electrons shells
3) The nuclear charge increases but this is not enough to outweigh the change in atomic radius
OVERALL IONISATION ENERGY DECREASES
How does ionisation energy change across a period?
1) Proton number increases so there is increased nuclear attraction to the outer electrons
2) The atomic radius decreases due to more attraction
3) No additional shells so electron shielding remains the same
OVERALL IONISATION ENERGY INCREASES
Why does ionisation energies decrease from Be to Boron if they are in the same period? (group 2 and 3)
Another subshell (p) was needed and therefore atomic radius increases. 2p orbital has higher energy level therefore easier to remove
Why does ionisation energy decrease from N and O? (group 5 and 6)
Start of electron pairing (spin paired)of the P shell. Electrol repel each other making it easier to remove an electron