Chem161 Chapter 14

Ionic hydrides (salt like)

Occurs when hydrogen reacts with very reactive metals

Covalent hydrides

hydrogen reacts with nonments

metallic hydrides (intersititial)

H2 and H molecules occupy holes in crystal structure of metal due to transition metals high electron affinity with eachother

why is the periodic trend of IE in group 2A inconsistent?

Because the changing amount of electrons in the orbitals changes the stability (half-filled is generally more stable than partially full)

What does gaseous Be look like?

Be has 4e- surrounding it, no octet. linear in shape

How does BeCl2 overcome electron deficiency?

In the solid state, it forms a polymeric structure with bridging 2 more chlorine atoms that share their electrons using bridge bonds

Be is a ___________

metalloid

Nitrogen can _____ bond

triple

Alkali metals e- are relatively far from the nucleus, causing weak ______ ________, lower______ and ________

metallic bonding, melting/boiling points, densities

Lattice energy increases as the size of the cation _______ and its charge ________

decreases, increases

what is lattice energy?

amount of energy required to break molecules and melt with one mole of substance into individual units

What is lattice energy based on ?

How strong cation and anion are bonded together in a matrix

why does BeCl2 have the highest lattice energy seen in the chart?

because breaking a covalent coordinate bond with a strong polymeric matrix requires more energy than breaking ionic bonds

why does group 1A have a lower lattice energy than 2A?

Because 1A has a lower charge density compared to 2A (1+ vs 2+)

what is the trend of density down 1A look like?

density increases as size increases because the added protons and neutrons outweigh the size increase

Alkali metals are powerful _______ agents

reducing

alkali metals react with H2 to form ionic ______

hydrides

why does AlCl3 have similar bonding patterns with BeCl2

they have a diagonal relationship that gives them similar properties

how does AlCl3 bond and a solid?

Aluminums halides exist as covalent dimers, giving Al one extra bond

Born is electron-deficient and therefore works as a _______ ______ since it can accept a E- pair

lewis acid

Boron can form ______ bonds with hydrogen

bridge

lewis acid ____ electrons

accepts

lewis base ______ electrons

gives

what two types of bonds are common in diborane

bridge bonding with H, normal covalent bonding with H

list the allotropes of carbon

graphite, diamond, fullerenes, nanotubes, graphene

catenation

process where carbon bonds to itself

the silicate building unit is ________ grouping (SiO4- tetrahedral)

orthosilicate

Si and O can make _____ chains forming most crystals, gems, etc

big

group 4A are generally ______ agents

reducing

oxygen is generally a ______ agent

oxidation

what are the two allotropes of phosphorus and their properties?

white phosphorus (P4) - contains strained bonds from narrow internal angle causing potential energy that makes it easily broken and reactive

red phosphoruc (P8) - forms diamond shaped structures that are very stable

electronegativity involves _____ compounds. Lattice energy involves _____.

covalent; ionic

electron affinity

energy released to capture and electron