Unit 2 Final Flashcards
The Lewis dot formula fails
To explain the formation of chemical bonds and gives no idea about the shapes of polyatomic molecules
VSEPR theory fails in what way
It gives the geometry of simple molecules but theoretically it doesn’t explain them and it has limited application
Covalent bonds are more clearly represented using
- the valance bond theory
- molecular orbital
What is the basic principle of valance bond theory
Covalent bond forms when orbitals of Two atoms overlap
______bond the electron density lies along the nuclear axis between the bonded nuclei
Sigma
In_________bond electron density is found in lobes above and below nuclear axis
Pi
_____ bond is stronger than______bond
Sigma
Pi
Hybridisation explains
Molecular structure specifically bond angle
Even though it provides a useful and convenient method for predicting the shapes of moléculas but it doesn’t explain the reason for the shape
Some possible hybridisation are
3s➡️ 3p➡️ 3d
3d➡️ 4s ➡️ 4p
They are all possible because they have comparable energies
What is diagonal hybridisation
Is when the central atom is hybridised -sp and is linked to Two other central atoms
2 electron pair
Linear -180
Sp
3 electron pair
Trigonal planar- 120
AB2E1- bent ,angular or v shape -104.5
Sp2
4 electron pair
Tetrahedral- 109.5
AB2E2- bent, angular or v shape- 104.5
AB3E - Trigonal pyramid - 107
Sp3
5 electron pair
Trigonal bipyramid- 90&120
AB3E2- t shape - 90
AB4E - see saw - 90
AB2E3- linear - 180
Sp3d
6 electron pair
Octahedral- 90&180
AB5E- square pyramid - 90
AB4E2 - square planar- 90
Sp3d2
Paramagnetic
Unpaired electrons - attracted by a magnetic field
Diamagnetic
All electrons are paired
Is not attracted by magnetic field and is slightly repelled
In diatomic molecules when the total electron is 14 or less the order is
σ1s σ1s* σ2s σ2s* ( π2py= π2pz) σ2px ( π2py * = π2pz * ) σ2px *
In diatomic molecules when the total electron is greater than 14 the order is
σ1s σ1s* σ2s σ2s* σ2px ( π2py= π2pz) ( π2py * = π2pz * ) σ2px *
Examples of crystalline structure
NACl and table sugar( sucrose)
Ionic bonds conduct electricity when
Molten or dissolved
For molecular crystals among polar molecules what intermolecular forces dominates? Among non polar what intermolecular forces dominates?
- dipole- dipole forces and whenever possible hydrogen bonding dominates
- London dispersion forces are the principal force
The most important network covalent solids are
Silicates
The two common crystalline forms of elemental carbon _____________and___________are examples of network covalent solids
graphite and diamond
Solids like molecular crystals are common among
Organic compounds and inorganic compounds
What are the fundamental units of the four crystals
Molecular solids: molecules or monatomic elements
network covalent solids : atoms covalently bonded to their neighbours
Metallic Crystals : identical metal atoms
Some assumption of the kinetic theory of matter are
- All matter is composed of particles that are constantly moving.
- All particles have kinetic energy and potential energy
- The difference between the three states of matter is the energy contents they
have and the motion of the particles. A change in phase may occur when the
energy of the particles is changed.
Lack of defined shape for liquid arises from
Low intermolecular forces of attraction
A gas is a collection of particles in constant__________motion
straight-line
the gaseous state is characterized by the following physical properties:
- Gases exert pressure equally in all directions
- Gases mix evenly and completely
The first reliable measurement on the properties of gases was made by
Robert Boyle
The si unit of pressure is
Pascal
1 atmosphere is equal to
760mmHg= 76cmHg= 760 torr=101,325 pa
The si unit of volume is
Cubic meter ( m3)
1cm3 is equal to
1dm3 is equal to
- 1 × 10^-6
- 1 × 10 ^-3 = 1L
1 liter is equal to
1000ml= 1000cm3= 1dm3
Convert kelvin to Celsius and farhaniet to Celsius
k = c + 273
C= (f-32) 5/9
At stp pressure and temperature are?
The molar volume of gas is ?
1 atmosphere, 0c (273k)
1 mole = 22.4 liter
The Boyle’s law formula
V1p1 =V2p2
____________is considered as absolute zero, which is theoretically the lowest attainable temperature, but practically cannot be attainable.
0 K (-273 °C)
________ was the first person to fill a balloon with hydrogen gas and who made the first balloon flight.
Charles
Gay Lucas law formula
P/t = P/t
Charles law
V/t= V/t
The avogardos law
V/n= V/n
The combined law formula
PV/T = PV/T
The ideal gas law is a combination of? Formula?
- Boyle’s law, Charles’ law and Avogadro’s law
- V = Rn T /P
n= molar mass/ given mass
The spreading of gas molecules throughout the container is called
diffusion
The Graham’s law of diffusion formula?
r1/r2= square root ( D2/D1)
r1/r2= square root ( M2/M1)
what are volatile liquids and give examples
- liquids evaporate readily at room temperature
- have relatively weak forces of attraction between particles
- Liquids such as formaldehyde, ethyl alcohol, mercury, and benzene are volatile liquids.
What are non volatile liquids
- Liquids that do not vaporize easily at a given temperature
- have relatively stronger attractive forces between their molecules
- motor oil, edible oil, glycerin, water, and molten ionic compounds
________and__________ have relatively low vapor pressure because of the very strong hydrogen bonding in these liquids
ethanol and water
____________, a non-polar molecule with relatively weak dispersion forces, has a relatively higher vapor pressure.
diethyl ether
Melting and freezing happen at __c
0 degrees Celsius
What is sublimation
Solid ➡️ gas
What is deposition
Gas ➡️ solid
Temperature is ___________ at the plateau that a phase change occurs
Constant
What does kinetics mean
Movement or change
the rate of reaction at the beginning is _______and it__________ as the reaction proceeds
fast
decreases
In a graph we use the slope of the hypotenuse to get
The rate
The steeper the slope
The faster the rate
What happens when gaseous phase each with each other ? When solutions react with each other?
- the reactions occur through the whole thing but when other phases react reactions occur at the boundary or interphase between two phases
If small pieces of metal iron and sodium are left in air which one reacts faster
The sodium reacts completely overnight whereas the iron is barely affected
The active metals sodium and calcium both react with water to form hydrogen gas and the corresponding metal hydroxide
Which is faster
calcium reacts at a moderate rate, whereas sodium reacts so rapidly that the reaction is almost explosive.
Is the combustion of graphite a heterogenous reaction or homogeneous reaction
Heterogenous reaction( solid with gas)
the rate of a reaction in a homogeneous system is approximately____________ by an increase in temperature of only 10 °C
doubled
