3.1.1: Periodicity Flashcards
Define the term first ionisation energy
the energy required/ energy change to remove an electron from each atom in one mole of gaseous atoms to form one mole of gaseous ions
Write an equation for the second ionisation energy of oxygen
O+(g) → O2+(g) + e-
Suggest why the second ionisation energy of oxygen has a greater value than the first
the O+ ion, is smaller than the O atom
OR the electron repulsion/shielding is smaller OR the same number of protons/nuclear charge attracting a fewer number of electrons
How do ionisation energies mark a new shell ?
Large difference between ionisation energies mean a new shell closer to the nucleus
Describe and explain trends across period 2 Li –> N
- Li —>N ionisation energy increases as atomic radius decreases, nuclear charge increases, nuclear attraction increases and electrons experience same shielding
- Be —> B ionisation energy decreases as electron is removed from p orbital which has a higher energy
Why does nuclear attraction increase
Because shell is drawn in closer to nucleus due to increased nuclear charge/ electrons experience greater attraction
What does a sharp rise in successive ionisation energy between 3rd and
4th IE indicate ?
The element is Al as it marks a change to a new shell / there are 3
electrons in the outer shell
Explain why the first ionisation energy of B is less than that of Be
-In B, electron being removed is at a higher energy
-In Be, electron being removed is at a lower energy
-An s electron is lost in Be AND a p electron is lost in B
Why is the second ionisation energy of Ca greater than the first ?
-same number of protons or same nuclear charge attracting
-less electrons and ion is smaller
- Nuclear attraction increases
How is the periodic table arranged ?
By increasing atomic number
Why is the periodic table not arranged by atomic mass ?
Atomic mass changes due to isotopes
Give 2 physical properties of metals
Conduct electricity and are ductile
Give 2 chemical properties of metals
- Form ionic compounds with non metals
- Form positive ions by electron loss
Give 2 physical properties of non metals
Brittle and poor electrical conductor
Give 2 chemical properties of non metals
- Form ionic compounds with metals
- Form negative ions by electron loss
Give the history of the development of the periodic table
- Ordered by atomic mass
- TRIADS - grouped into 3s by characteristics
- NEWLANDS OCTAVES - grouped by mass with every 8th element having similar properties however transition metals didn’t fit patters
- MENDELEEV - ordered by atomic mass, left gaps for undiscovered elements and predicted properties
- ORDERED BY PROTON NUMBER - periods and groups
Is ionisation energy endothermic or exothermic ?
Requires energy so is endothermic (positive value)
Give the 3 factors affecting ionisation energy
Atomic radius, nuclear charge, shielding