Module 3 - The Periodic Table And Periodicity Flashcards
What is the magnitude of an ionisation energy influenced by??
Nuclear charge
Atomic radius
Shielding
Effect of nuclear charge
The greater the nuclear charge the greater the attraction on the outer electrons
Effect of atomic radius
The further the electrons is from the nucleus, the weaker the attraction
Effect of shielding
Full inner shells of electrons exert a repelling effect on outer electrons. This reduces the attraction between the nucleus and outer electrons
Trends in first ionisation energy
Decrease down a group
Nuclear charge increases
Atomic radius increases so outer electron is further from the nucleus
Shielding increases as the number of full inner shells increases
Increase in distance and shielding outweighs the increased nuclear charge
Nuclear attraction on outer electron decreases
First ionisation energy decreases
Trends in first ionisation energy
General increase across a period
Nuclear charge increases
Atomic radius decreases so outer electron is closer to the nucleus
Shielding stays the same as electrons are added to the same shell
Nuclear attraction on outer shell increases
First ionisation energy increases
Decrease between groups 2 and 3
2p orbitals have slightly more than 2s
S electrons provide slightly greater shielding of the p electron
Less energy needed to remove outer electron despite increased nuclear charge
Decrease between groups 5 and 6
Spin pairing occurs in 2p subshell of oxygen
Paired electrons in a 2p orbital of oxygen repel each other
Less energy needed to remove outer electron despite increased nuclear charge
What is the atomic orbital
Region around the nucleus that can hold up to 2 electrons with opposite spin
General trend in the first ionisation energies of the first 11 elements
Nuclear charge increases
Atomic radius decreases
Outer electron is closer to the nucleus, shielding stays the same as electrons are added to the same shell
So ionisation energy increases across a period
Group number
Number of outer shell electrons
Period number
Number of electron shells
Periodicity
The repeating trend in physical and chemical properties across periods of the period table
Structure of a metallic lattice
Cations are in fixed positions giving the shape of the metal
Delocalised electrons are mobile and can move throughout the structure
What is a metallic bond??
A strong electrostatic attraction between a lattice of positive ions and a sea of delocalised electrons
Electrical conductivity in giant metallic lattices
Delocalised electrons can move and carry charge
Electrons will move towards the positive terminal, electrons will be supplied by the negative terminal
Melting and boiling points in giant metallic lattices
High due to large amount of energy needed to overcome the strong electrostatic attractions between positive ions and delocalised electrons
Metallic bond strength depends on number of outer shell electrons to be delocalised and charge density of the metal ion
Solubility in giant metallic lattices
All insoluble
Some will react with water
Structure of giant covalent lattices
Atoms held together in a network of strong covalent bonds forming a giant covalent lattice
Electrical conductivity of giant covalent lattices
Non-conductors, no delocalised electrons all outer shell electrons are used in bonding
Exception - graphite - delocalised electrons are present which can move
Melting points and boiling points of a giant covalent lattice
High due to the large amount of energy needed to break the many strong covalent bonds
Solubility of giant covalent lattices
All insoluble
What is a homologous series??
A series of organic compounds having the same functional group but with each successive member differing
What is the general formula??
The simplest algebraic formula for a member of a homologous series
What is the structural formula??
The minimal detail that shows the arrangement of atoms in a molecule
What is the displayed formula??
The relative positioning of atoms and the bonds between them
What is the skeletal formula??
The simplified organic formula showing only a carbon skeleton and associated functional groups
Functional group
A group of atoms responsible for the characteristic reactions of a compound
Formula for an alkyl group
CnH2n+1
What does aliphatic mean??
A compound containing carbon and hydrogen
Joined in straight chains, branched chains or non-aromatic rings
What does alicyclic mean??
An aliphatic compound arranged in non-aromatic rings with or without side chains
What does aromatic mean??
A compound containing a benzene ring
What does saturated mean??
Single carbon carbon bonds only
What does unsaturated mean??
The presence of multiple carbon-carbon bonds
What is a structural isomer??
Compounds with the same molecular formula but different structural formula
Why does ionisation energy increase across a period??
Increasing nuclear charge
No change in shielding
Atomic radius decreases
Nuclear attraction increases
More energy needed to remove outer electron
Why does ionisation energy decrease down a group??
Atomic radius increases
More full inner shells so more shielding
These factors outway the increased nuclear charge
Nuclear attraction decreases
Less energy is needed to remove the outer electron
Why do successive ionisation energies increase??
Same nuclear charge
Fewer electrons
Electrons pulled closer to the nucleus
Nuclear attraction increases
More energy needed to remove the next electron
What is atomic orbital??
Area around the nucleus that can hold 2 electrons with opposite spin
What is an orbital??
A region around the nucleus that can hold up to 2 electrons with orbital spin
What is a shell??
Region around the nucleus which contains orbitals with the same principle quantum number
What is a subshell??
A group of orbitals with the same principle quantum number
How to detect carbonate ions are present
Add dilute nitric acid
Indication that carbonate ions are present when dilute nitric acid is added
Effervescence
How to prove gas produced is carbon dioxide??
Bubble gas through limewater which will turn cloudy
How to detect sulphate ions
Add nitric acid and barium nitrate solution