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40 Cards in this Set

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What are the properties of metals (electronegativity and conductivity)?

Low electronegativites.




Good electrical and thermal conductivity, due to metallic bonding (delocalised electrons).

What are the properties of metalloids (electronegativity and conductivity)?

Intermediate electronegatvities.




Semiconductors, due to covalent bonds (localised electrons, become partially delocalised at high temp).

What are the properties of non-metals (electronegativity and conductivity)?

High electronegatvities.




Insulators, molecules with covalent bonds - often large lattices.

What electrons can serve as valence electrons?

Only S and P electrons.

What is the definition of the inert pair effect?

The reluctance of heavy p-block elements to share their s-electrons. - especially seen in period 6.

What causes the high inertness in the 6s pair?

Due to a poorly shielding 4f-subshell and the relativistic effect.

Eredox = ?

Ereduction - Eoxidation

When will a reaction proceed spontaneously?

if Ereduction > Eoxidation

Structure & Bonding - Metals vs Non-metals




Valence Shell?

Metals: Electron-deficient, high energy due to low Zeff.




Non-metals: Electron-rich, low in energy due to high Zeff.

Structure & Bonding - Metals vs Non-metals




Bonding?

Metals: Valence electrons delocalised across the structure (metallic bonding).




Non-metals: Valence electrons are localised in bonding or non-bonding orbitals (covalent / lone pairs).

Structure & Bonding - Metals vs Non-metals




Structure?

Metals: Densely packed atoms, non-directional bonds.




Non-metals: Molecular or polymeric, strong directional bonds - hybridization of s & p orbitals.

Discrete energy levels are only observed for molecules in the?

Discrete energy levels are only observed for molecules in the gas phase

Where is pi-bonding most effective?

Most effective in the first row of p-block elements, atoms are small and therefore have effective overlap.

Why does metallic character decrease down the groups?

metallic character decreases down the groups as atoms become larger, weaker bonds - less hybridisation due to less efficient orbital overlap.

what are allotropes and why do they occur?

Allotropes are different modifications of the same element, can arise from different types of bonding - metallic vs covalent, sigma vs p and directional covalent bonding (which will lead to a different network structure for the same base unit)

why is diborane electron deficient?

it has too few electrons to form conventional 2-center 2-electron sigma bonds between all its atoms.




(BHB bridges can be described as 3-center-2-electron bonds)

What is the type and skeletal electron pair for the formula [BnHn]2-

Closo, n+1

What is the type and skeletal electron pair for the formula BnHn+4?

Nido, n+2

What is the type and skeletal electron pair for the formula BnHn+6?

Arachno, n+3

What do closo clusters only feature?

Terminal H-atoms

What can nido and arachno clusters contain?

Bridging and terminal H-bonds

Define bond dissociation energy

The measure of strength of an A-B bond; standard reaction enthalpy for the process AB(g) --> A(g) + B(g)

Why do homo-nuclear bonds become weaker down the group?

There is less efficient orbital overlap between the larger atoms

What can the strength of an heteronuclear bond depend on?

The polarity of the bond

Define electronegativity

electronegativity is the power of an atom in a molecule to attract electrons to itself

define atomic radius

half the length of a homonuclear bond

define oxidation state

the charge remaining on an atom when all ligands are removed heterolytically in their closed form, electrons are transfered to the more electronegative partner.

why are compounds of 2nd and higher row p-block elements highly unstable with unpaired electrons?

there outer spx orbitals are fairly directional and are reluctant to form pi bonds

what is hyper-valency?

p-block atoms with high coordination numbers that violate the octet rule

why can some atoms have large coordination numbers?

larger atomic radius and polar character of bonds

What makes a material ferroelectric?

A permanent dipole that can be reversed by application of an external electric field

why do chlorides of p-block elements serve as important starting materials for p-block based materials/compounds?

they are reactive Lewis Acids

what are isoelectronic species?

different atoms with the same number of electrons/electronic structure

what bonding do Organometallic compounds of s-block metals have? What are they sensitive to?

Organometallic compounds of s-block metals are largely ionic; they contain carbanions.They are very air and moisture sensitive and must be stored under inert gas atmosphere.

Group 13 organometallics are all ...




handled under?

- electron deficient Lewis Acids


- air sensitive




handled under inert conditions

How does the Lewis Acidity of Group 13 organometallics change down the group?

The acidity of organometallics decreases down Group 13.

Oxides and hydroxides of electropositive elements are ___ and show ___ reactions?

Oxides and hydroxides of electropositive elements are ionic and show basic reactions?

Oxides and hydroxides of electronegative elements are ___ and show ___ reactions?

Oxides and hydroxides of electronegative elements are covalent and show acidic reactions?

How do you know if an oxide or hydroxide is amphoteric?

Oxides/hydroxides of elements at the metal metalloid boundary are amphoteric

Why does CCl4 not react with water?

It is kinetically stable towards electrophilic attack