Class 2 Flashcards
How do you determine the number of valence e-?
Group number on periodic table
how do you determine formal charge?
Valence e- - sticks - dots
What are the exceptions to the octet when determining formal charge?
H/He have 2e-
Be has 4e-
B has 6e-
How do you determine the hybridization of an atom?
2 groups (bond or lone pair)= sp, linear, triple bonds
3 groups= sp2, trigonal planar, double ponds
4 groups= sp3, tetrahedral, single bonds
What happens always when you break a bond?
Its always an endothermic process
What is a covalent bond?
e-s are shared, degree to which they are shared is polar or non polar
- polar bonds have some ionic character
- polar bonds tend to be stronger
How is a molecular dipole found?
By adding all the bond dipoles
-but done dipoles will cancel symmetric geometries
What is a metallic bond?
Bond between metal and metal
-all e- are shared between all metal atoms and are malleable
What is a coordinate covalent bond ?
Atoms with lone pairs (Nu- Lewis base) and e- deficient species (E+ Lewis acid)
What is a ligand?
A Nu- which donates e-
What is an ionic bond?
Formed between atoms of opposite full charges (cations metals lose e-, anions non metal gain e-)
-e- are localized on the ions and dissociate in aqueous solution as an electrolyte
What are IMF?
Forces between molecules when particles of opposite charge attracts each other
What is the strength of the IMF dependent on?
Larger charges= stronger attraction force
What is ion dipole forces?
Produced between Ions and polar molecules
-larger the ionic charge and dipole the larger the force
What is dipole dipole force?
produced between polar molecules no bond dipole
-more polar molecule=stronger force and easily cleaved
What is a dipole induced dipole force?
Between polar and non polar, normally in mixtures
-force generated when a polar attracts e- density in a non polar molecule
what is LDF?
London dispersion forces are between all molecules as long as you have e- you experience this force
- produced when molecules collide and distort the e- cloud
- larger size of molecule and more e-=stronger force
What is h bonding?
produced between very polar molecules formed between donor (NH,OH,FH) and acceptor (NOF). anything else won’t form an h bond
What species cant you form a H bond with?
Same species
What is the order of the relative strengths of the different types of bonds?
Ionic> POlar covalent> Nonpolar. covalent>metallic> coordinate covalent
What us the order if the relative strength of the different type of IMF?
Ion dipole> Hbonding> dipole dipole> dipole induced dipole>London dispersion forces
What is enthalpy (H)?
energy stored in chemical bonds and attraction forces (IMF)
What. is the difference between exothermic and endothermic?
Exo= heat released and energy is less in the products
End= heat absorbed and energy is more in products
How do you calculate the delta h of rxn?
bonds broken -bonds formed
What is the delta Hf?
energy t form one mol of compound from its constitutive elements in its standard state
how do you calculate delta Hf?
products -reactants.
Is enthalpy independent of path?
it is. a state function so independent of pathway
-if reverse direction switch the sign
What is entropy (S)?
Disorder and potential randomness
S>0 favourable
S<0 unfavourable
What is the entropy and enthalpy in going from a solid to gas?
Entropy is increasing so its favourable
Enthalpy is decreasing so unfavourable because its endothermic
What can increase entropy?
Increasing temp
What is free energy (G)?
Energy present in system to do work
- exergonic (-) spontaneous and favourable
- endothermic (+) non-spontaneous and unfavourable
What does spontenaiety mean?
having a - value of G regardless of rate
What is the equation for delta G?
H-TS
What if H and S have the same sign?
then G tis temp dependent
What is H and S have different signs?
Its not temp dependent it will always be never or always spontaneous
What happens if booth H and S are -?
Spontaneous at decreased temp
What is both S and H are +?
Spontaneous at increased temp
