Periodicity Flashcards
(25 cards)
What is periodicity?
The repeating pattern of physical or chemical properties going across the periods.
How does atomic radius change across a period?
It decreases due to more protons, same shells, same shielding, and greater nuclear attraction.
What happens to atomic radius down a group?
It increases due to more shells (energy levels) and greater distance between nucleus and outer electrons.
What is electronegativity?
The power of an atom to attract the two electrons in a covalent bond.
How does electronegativity change across a period?
It increases due to more protons in the nucleus and a smaller atomic radius.
What happens to electronegativity down a group?
It decreases due to more shells and larger atomic radii, leading to weaker attraction between outer electron and nucleus
What is the trend of ionisation energy down a group?
Ionisation energy decreases down a group.
This is due to more shells, greater distance between nucleus and outer electron, and weaker attraction between nucleus and outer electron.
What is the trend of ionisation energy across a period?
Ionisation energy increases across a period.
This occurs because there are more protons in the nucleus while the electrons are in the same shell, resulting in a stronger attraction.
What happens to the ionisation energy when moving from Group 2 to Group 3?
Ionisation energy decreases from Group 2 to Group 3.
Electrons lost from Group 2 are in the s orbital, while those from Group 3 are in the p orbital, which is higher in energy.
What is the difference in electron loss between Group 5 and Group 6?
Group 5 elements lose an electron from an orbital with 1 electron, while Group 6 elements lose an electron from an orbital with 2 electrons.
The extra electron in Group 6 causes electron repulsion, making it harder to lose an electron compared to Group 5.
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.
Which elements are in Period 2?
Li, Be, B, C, N, O, F, Ne
Which elements are in Period 3?
Na, Mg, Al, Si, P, S, Cl, Ar
What trend does atomic radius follow across a period?
Atomic radii decrease from left to right across a period.
Why does atomic radius decrease across a period?
The increased number of protons creates more positive charge attraction for electrons in the same shell with similar shielding.
What is the trend in first ionization energy across a period?
There is a general trend to increase in first ionization energy across a period.
What causes the small drop in ionization energy between Mg and Al?
Mg has its outer electrons in the 3s subshell, whereas Al is starting to fill the 3p subshell, making Al’s electron slightly easier to remove.
What causes the small drop in ionization 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 melting and boiling point trend for Na, Mg, and Al?
They exhibit strong metallic bonding, which gets stronger with more electrons in the outer shell.
What type of bonding does silicon (Si) exhibit?
Silicon is macromolecular with many strong covalent bonds between atoms.
What type of bonding do Cl, S, and P exhibit?
They are simple molecular with weak van der Waals forces between molecules.
Why does sulfur (S) have a higher melting point than phosphorus (P)?
Sulfur has more electrons, resulting in stronger van der Waals forces between molecules.
What type of bonding does argon (Ar) exhibit?
Argon is monoatomic with weak van der Waals forces between atoms.
