3.1 The periodic table Flashcards
periodic table arrangement
increasing atomic (proton) number
in periods showing repeating trends in physical and chemical properties (periodicity)
in groups having similar chemical properties
periodicity definition
repeating trend in properties in each element across a period
periodicity in electron configuration
electron added to highest energy level
s sub-shell filled in group 1-2, p sub-shell filled onwards
same in each period (periodic pattern)
electron configuration trend down a group
same number of election in outer shell
gives elements in same group similar chemical properties
first ionisation energy definition
energy required to remove one electron from each atom in 1 mole of gaseous atom to form 1 mole of gaseous 1+ ions
factors affection ionisation energy
atomic radius (greater distance between nucleus and outer electrons = less nuclear attraction, large effect) nuclear charge (more protons in nucleus = greater attraction between nuclear and outer electrons) electron shielding (inner shell electrons repel outer shell electrons due to negative charges, reduces attraction between nucleus and outer electrons - shielding effect)
successive ionisation energies
greater than previous ionisations
first electron is lost
same number of protons, less electrons so greater attraction to each electron
pulls electron closer to nucleus
nuclear attraction increases in outer shell electron so more energy required to ionise successively
how to work out number of electrons in shells with successive ionisation energies
sharp increase = new shell
number of ionisations in line = number of electrons in shell
can work out element, group of element, number of electrons in outer shell
first ionisation energy trend down a group
atomic radius increases
more inner shells, shielding increases
nuclear attraction on outer electrons decrease
first ionisation decreases
periodicity in first ionisation energy (general trend)
nuclear charge increases same number of shells, similar shielding nuclear attraction increases atomic radius decreases first ionisation energy increases
why first ionisation drops from beryllium to boron
only 2s sub-shell filled in beryllium
2p sub-shell also filled in boron
2p on higher energy level than 2s so easier to remove
first ionisation lower in boron than beryllium despite higher nuclear charge
why first ionisation decreases from nitrogen to oxygen
highest energy level elections in 2p sub-shell
oxygen has paired electrons in one of 2p orbitals
repel one another, nuclear attraction decreases
first ionisation energy less in oxygen than nitrogen
metallic bonding definition
strong electrostatic attraction between cations and delocalised electrons
giant metallic structure lattice
atoms donate outer shell electrons to form sea of delocalised electrons
cations fixed in position
delocalised electrons mobile and able to move throughout structure
charges of cations and delocalised electrons balance
electrons spread out and shared between all cations
forms giant metallic lattice
properties of metals
strong metallic bonds
high electrical conductivity
high melting and boiling points
why metals have good electrical conductivity
in solid and liquid states
delocalised electrons can move as carry charge (charge carriers) in structure when voltage applied
why melting and boiling points of metals are high
strong electrostatic attraction between cations and delocalised electrons
high temperatures necessary to provide large amount of energy to overcome metallic bonding
solubility of metals
don’t dissolve
any interaction with water results in a reaction
giant covalent lattices
billions of atoms held together by network of strong covalent bonds
forms giant covalent lattice
carbon and silicon form tetrahedral structure (group 4, electron-pair repulsion)
properties of giant covalent lattices
high MP/BP
insoluble in almost all solvents
non-conductors (apart from graphene and graphite)
why giant covalent lattices are generally insoluble
covalent bonds between each atom too strong to be broken by interactions with solvent
why giant covalent lattices have high MP/BP
covalent bonds are strong
require lots of heat energy to break covalent bond