Periodicity Flashcards
State the meaning of periodicity
Repeating trends
State the meaning ionisation energy
The minimum amount of energy required to remove one mole of electrons from one mole of gaseous atom to form (one mole of gaseous +1 ions )
Define atomic radius
Total distance from the nucleus of an atom to the outer shell of the electron
State the largest atomic radius in period 3
Na
-smallest nuclear charge
- sheilding stays the same
State the trend in atomic radius across the period
-Atomic radius decreases
-Nuclear charge increases
-Shielding stays constant
-Same energy level
State the trend in atomic radius down the group
Atomic radius increase
-electron shell is added
- increasing the distance between the outer electron and the nucleus reducing the power of attraction
- increase in shielding
State the trend in atomic radius down the group
Atomic radius increase
-electron shell is added
- increasing the distance between the outer electron and the nucleus reducing the power of attraction
- increase in shielding
Explain why the atomic radius decreases across period 3 from Na to cl (3 marks )
- nuclear charge increase
- shielding is constant
-same number of shells
Identify the element in period 4 with the largest atomic radius (3marks )
Potassium
-smallest nuclear charge
-shielding remains constant
Deduce which of Na* and mg2* is the smaller ion (2marks )
Mg2*
-has more protons with the same number of shielding
State the trend in ionisation energy across the period
-Increases
-atomic radius decrease
-nuclear charge increase
-outer electron held more strongly more energy required to remove the outer electron and ionise
State the trend in ionisation energy down the group
-Decreases
-nuclear attraction between the nucleus and outer electrons reduces
- shielding increases
-less energy required to remove outer electrons
Explain why there’s a decrease in ionisation energy from mg to Al
-Outer electron in the 3p orbital for Aluminium which is higher in energy compared to 3s
-increase shielding
State the element in period 3 that has the highest first ionisation energy
- argon
-largest nuclear charge
-energy levels are the same
Write an equation to represent the process when the first ionisation energy for sodium is measured
Na(g) ~> Na*(g) + e~
Explain why the first ionisation energy of sultry is different from that of phosphorus (2 makrs )
-electron in 3p orbital for sulfur is paired
-repulsion occurs for paired electron
-3p4 is easier to remove then 3p3
What happens to melting points across period 3 between sodium and aluminium
Na,Mg,Al
-general increase
-metallic bonding
-melting points increase due to increase in positive charge
-increases the electrostatic attraction forces more energy required to overcome these forces
Which element in period 3 has highest melting point
Silicon
Which element in period 3 has the lowest melting point
Argon
State the element in period 3 that has the highest melting point (3 marks )
-Silicon
-covalent bonds
-strong covalent bonds needs to be broken
-requires a lot of energy to break the covalent bonds
Explain what happens between p,s,cl
ar In terms of melting points
Huge decrease from silicon to phosphorus
- silicon higher as is s8 rather then p4
Larger covalent then p4
Stronger vdw forces
Cl - is low as gas at room temp
Argon - is lowest - noble gas weak vdw
Explain in therms of structure and bonding , why the melting point of carbon is high (3 marks )
- macromolecules
-covalent bonds in structure
-string covalent bonds must be broken to break these bonds requires alot of energy
