Periodicity Flashcards
What is the first ionisation energy?
Energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.
What is the equation for the first ionisation energy?
X(g)-> X+(g) + e-
What is ionisation energy?
A measure of how easily an atom loses electrons to form positive ions.
What are 3 factors that affect ionisation energy?
Atomic radius, the greater the atomic radius the weaker the attraction. Nuclear charge, the more protons, the greater the attraction. Electron shielding, as number of shells increase the shielding increases.
What is the second ionisation energy?
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
What is the equation for second ionisation energy?
X+(g) -> X2+(g) + e-
How are elements arranged in a periodic table?
Order of increasing atomic number
What is meant by periodicity?
The repeating trends in chemical and physical properties
How can the electron configuration be written in short?
The noble gas before the element is used to abbreviate
Describe the trend of ionisation energy across period 3.
First ionisation energy increases because
- Nuclear charge increases
- Decreased atomic radius
- Same electron shielding
Which means more energy is needed to remove an electron
Why does ionisation energy decrease from Mg to Al?
Al is in the 3p orbital which has a higher energy level than 3s in Mg so its easier to lose an electron
Why does ionisation energy decrease from phosphorus to sulphur?
In sulphur, the 2 electrons in the first 3p orbital repel making it easier to lose an electron
Why does first ionisation energy decrease between group 2 and 3?
Group 3 outer most electrons are in the p orbitals whereas in group 2 they are in s orbital, so the electrons are easier to be removed
Does first ionisation energy increase or decrease at the start of the next period?
Decrease, as there is an increase in atomic radius and increase in shielding
Why does first ionisation energy decrease between group 5 and 6?
The group 5 electrons in the p orbitals are single electrons and in group 6 the outermost electrons are spin paired, with some repulsion, making it easier to remove
Why does ionisation increase or decrease down a group?
Decreases because
- Shielding increases
- Atomic radius increases
- The increase in protons is outweighed by the increase in distance and shielding
What happens in metallic bonding?
Each atom donates its outer shell electrons to a shared pool of electrons (delocalised electrons), its the strongest type of bond between cations and delocalised electrons
What keeps atoms in metallic bonds in fixed positions?
The cations are in fixed positions maintaining the structure and shape of the metal
What makes the metallic bonds strong?
Strong attraction between positive ions and delocalised electrons
Do metals conduct electricity?
They conduct in solid and liquid states, when a voltage is applied the delocalised electrons can move, carrying the charge
Are metals soluble?
Metals do not dissolve, any interactions with water would lead to a reaction rather than dissolving.
What do non-metallic elements exist as?
Simple covalently bonded molecules, in a solid state they form a simple molecular lattice held together by weak forces
How many covalent bonds form between carbon lattices in diamond form and silicon?
They use their 4 outer shells to form 4 covalent bonds
What are giant covalent lattices melting and boiling points?
They have high melting and boiling points due to the strong covalent bonds
Are giant covalent lattices soluble?
Covalent bonds are far too strong to be broken down by interactions with solvents (insoluble)
Are carbon (diamond) and silicon able to conduct electricity?
No, all 4 outer shell electrons are involved in covalent bonding there none are available for conducting electricity
Why can graphite conduct electricity?
Only 3 outer electrons are used out of the 4 so the remaining one is released into a pool of delocalised electrons
Why does graphite have a lower boiling point than diamond?
The layers in graphite can slide over each other because the forces between them are weak.
What does it mean if there is an increase in ionisation energy between 3rd and 4th ionisation energies?
This shows that the fourth electron is being removed from an inner shell, therefore there are 3 electrons in the outer shell and the element must be in group 3 (Al)
Explain why xenon has a lower first ionisation energy than neon (Xe is lower down than Ne)
- Xenon has more shells
- Xenon has more shielding
- Therefore nuclear attraction decreases
Why does the modern Periodic Table not arrange some elements, such as those in order of increasing atomic mass?
- Arranged in increasing atomic number
- Wouldn’t show properties/trends of the rest of the group
Explain the difference in melting point for the elements Na and Mg
- Mg has a greater charge
- Mg has more electrons
- Mg has stronger metallic bonds
Sulfur exists as S8 molecules and chlorine as Cl2 molecules. Use this information to explain the difference in their melting points.
- S8 has more electrons than Cl2
- Therefore S8 has stronger intermolecular forces
Explain the decrease in the atomic radii across the period from Na to Cl
- Proton charge increases therefore greater pull on electrons
- Shielding remains the same
Explain the difference between the first ionisation energies of Li and Na.
- Na has more shielding
- Atomic radius increases
- Less nuclear attraction
Predict and explain whether a barium ion is larger, smaller or the same size as a barium atom.
- Smaller due to less shielding
Why does ionisation energy decrease from Be to B?
- An electron is being removed from a different sub-shell (p), which has a higher energy level
Why does ionisation energy decrease from Be to B?
- An electron is being removed from a different sub-shell (p), which has a higher energy level
Explain why a nitrogen atom is larger than an oxygen atom
- N has less protons than O
- Same shielding
- Weaker nuclear attraction in N
- Shell drawn in less for N
Explain why a nitrogen atom is larger than an oxygen atom
- N has less protons than O
- Same shielding
- Weaker nuclear attraction in N
- Shell drawn in less for N
Suggest why the second ionisation energy of oxygen has a greater value than the first
ionisation energy of oxygen
- O+ is smaller than O
- Shielding is smaller
