Module 3.1 - The Periodic Table Flashcards
What is meant by the term ‘periodicity’?
Arrangements of the elements in periods showing repeating trends in physical and chemical properties
How are the elements arranged in the periodic table?
By increasing atomic numbers
What is each horizontal row of the periodic table called?
period
What is each vertical column of the periodic table called?
group
Why do elements of the same group have similar properties?
Have the same number of outer shell electrons (repeating pattern of electron configuration) (have the same type of orbitals)
What does a higher principal quantum number show?
Higher energy level and shell further from the nucleus
Compare when the 4s orbital fills and empties with that of the 3p orbital.
- 4s energy level is lower than 3d energy level
- 4s orbital fills before 3d orbital
- 4s orbital would be emptied before 3d orbital during ionisation
What is meant by the term ‘first ionisation energy’?
The energy required to remove one electron from each atom in one mole of the gaseous element to form one mole of gaseous 1+ ions
What is the equation for the first ionisation energy of neon?
Ne(g) –> Ne+(g) + e-
How is an atom oxidised to 1+ ions?
Energy supplied to overcome attraction of positive nucleus to outer electrons (outer electrons as have least attraction so least ionisation energy)
What does nuclear attraction (and therefore ionisation energy) depend on and why?
- atomic radius (larger radius = less attraction to outermost electrons as further away)
- nuclear charge (high charge = greater nuclear attraction)
- electron shielding (inner shell repel outer shell as all -ve, repelling effect = electron shielding, more inner shells = larger shielding effect so smaller nuclear attraction by outermost electrons)
What is successive ionisation energy?
Values that measure the energy required to remove each electron in turn
What is the trend in successive ionisation energies and why?
- each successive ionisation energy is higher than the one before
- as each electron removed, less repulsion between remaining electrons and each shell drawn slightly closer to nucleus
- distance of each electron from nucleus decreases slightly so nuclear attraction increases so more energy to remove each successive electron
How do successive ionisation energies provide evidence for shells?
Large increases in ionisation energy show next shell in as atomic radius decreases massively
Why do noble gases have a higher first ionisation energy than the rest of the atoms in their period?
Full outer shell of electrons and high positive attraction from nucleus so ionisation energy values are large
What are the trend across the periodic table that can affect ionisation energy?
-increasing number of protons so higher attraction to electrons
-same shell so outer shell drawn inwards slightly
-same number of inner shells, so electron shielding hardly changes
∴ attraction between nucleus and outer electrons increases so more energy needed to remove an electron so 1st ionisation energy increases across a period
Why is there a small decrease in first ionisation energy between group 2 and 13 elements?
- group 13’s outermost electron in p orbital but group 2’s in s orbital
- p orbitals have slightly higher energy than s orbital so slightly further from nucleus
- electrons in theres orbitals are slightly easier to remove so elements have lower 1st ionisation energy
Why is there a small decrease in first ionisation energy between group 15 and 16 elements?
- electrons in p orbitals
- 13, 14, 15: each p orbital only has a single electron
- 16: electron now paired in a p orbital
- spin-paired electrons have some repulsion so slightly easier to remove so lower 1st ionisation energy
Why is there a sharp decrease in first ionisation energy between the noble gas if one period and the group 1 element of the next period?
- new shell added so outermost electrons further from nucleus
- increase in distance of outermost shell from then nucleus
- increase in electron shielding of outermost shell by inner shells
What is the trend of first ionisation energy down a group and why?
- 1st ionisation energy decreases
- no. of shells increases so outer electrons further from nucleus so weaker force of attraction on outer electrons
- more inner shells so shielding effect on outer electrons from nuclear charge increases so weaker attraction
- nuclear charge (no. of protons) increases but increased attraction outweighed by increasing distance/shielding
- attraction (nucleus and outermost electron) decreases so less energy to remove electron so lower 1 IE (causes larger atomic radius as electrons not pulled as close to nucleus)
What is the structure of a metallic lattice?
- metal cations in fixed position in lattice
- outer shell electrons are delocalised (sea of delocalised electrons) (shared between all atoms in metallic structure) and spread throughout structure
- electrons can move in structure (can’t match electron to cation it came from)
- charge balanced over whole structure
What are the properties of giant metallic lattices?
- high melting point and boiling point
- good electrical conductivity
- malleability and ductility (delocalised electrons give a degree of give)
Why do metals have high melting and boiling points?
- electrons free to move throughout structures but +ve ions remain where they are
- attraction between +ve ions and -ve delocalised electrons is v strong
- high temp needed to overcome metallic bonds and dislodge ions from their rigid position in lattice