inorganic chem; periodicity Flashcards
What is periodicity?
Periodicity is the repeating pattern of physical or chemical properties going across the periods.
How are elements classified in the periodic table?
Elements are classified as s, p, or d block, according to which orbitals the highest energy electrons are in.
What elements are in Period 2?
Period 2 = Li, Be, B, C, N, O, F, Ne.
What elements are in Period 3?
Period 3 = Na, Mg, Al, Si, P, S, Cl, Ar.
What trend is observed in atomic radius across a period?
Atomic radii decrease from left to right across a period due to increased positive charge attraction from protons.
What is the trend in 1st ionisation energy across a period?
There is a general trend to increase in 1st ionisation energy across a period.
Why is there a drop in ionisation energy between Mg and Al?
Mg has its outer electrons in the 3s subshell, whereas Al 3p electrons are higher in energy, making Al’s electron easier to remove.
Why is there a drop in ionisation energy between phosphorus and sulfur?
Sulfur’s outer electron is paired with another electron in the same 3p orbital, causing slight repulsion and making it easier to remove.
What is the trend in melting and boiling points for Na, Mg, and Al?
For Na, Mg, Al - Metallic bonding is strong and gets stronger with more outer shell electrons that are released to the sea of electrons.
What type of bonding does silicon exhibit?
Si is macromolecular with many strong covalent bonds, requiring high energy to break covalent bonds.
What type of bonding do Cl2, S8, and P4 exhibit?
Simple molecular with weak van der Waals forces, requiring little energy to break.
Why does sulfur have a higher melting point than phosphorus?
S has more electrons (S8 = 128, P4 = 60), resulting in stronger VDWs forces between molecules.
What type of bonding does argon exhibit?
Ar is monoatomic with weak VDWs forces between atoms.
How are elements ordered in the periodic table?
By proton number
