Chemistry 3

Front 1

Describe the definition relative atomic mass Ar?

Back 1

Average mass of 1 atom over a 12th of 1 atom of 12 C

Front 2

Describe the definition of relative molecular mass Mr?

Back 2

Average mass of molecule over a twelth of 1 atom of 12 C

Front 3

Describe why an vaccum is used during flight mass spectometer?

Back 3

A high vaccum is used to prevent the ions that are produced colliding with molecules from the air.

Front 4

Describe the process of Electronspray?

Back 4

In electronspray ionisation, the sample is dissolved in a volatile solvent and forced through a fine needle that is connected to the positive terminal of a high voltage supply. This produces tiny positivley charged droplets that have lost electrons to the positive terminal. The solvent evaporates from the droplets into the vaccum and the droplets get smaller and smaller until they may contain no more than a single positivley charged ion.

Front 5

Describe the process of electron impact?

Back 5

In electron impact, the sample is vaporised and high energy electrons are fired at it from an electron gun, which is a hot wire filament with a current runninh through it that emits a beam of high energy electrons.

Front 6

Describe acceleration?

Back 6

The positive ions are attracted towards a negativley charged plate and accelerated towards it. Lighter ions and more highly charged ions achiever a higher speed.

Front 7

Describe Ion drift?

Back 7

The ions pass through a hole in the negativley charged plate, forming a beam and travel along a tube, called the flight tube, to a detector.

Front 8

Describe detection?

Back 8

When ions with the same charge arrive at the detector, the lighter ones are first as they have higher velocities. The flight times are recorded. The positive ions pick up an electron from the detector, which causes a current to flow.

Front 9

How can mass spectrometer be used to identify different isotopes that make up an element?

Back 9

It detects individual ions, so different isotopes are detected seperately because they have different masses.

Front 10

Describe what high resolution mass is?

Back 10

Mass spectrometers can measure relative atomic masses to five dp of an atomic mads unit.

Front 11

Describe low resolution spectrometry?

Back 11

Measuring relative atomic masses to 1 dp of an atomic mass unit.

Front 12

Describe spin?

Back 12

Electrons have a property called spin:

Two electrons in the same orbital must have opposite spins.

The electrons are usually represented by arrows pointing up or down to show the different directions of spin.

Front 13

Describe the bonding of Na Mg and Al

Back 13

There is an increasi g strength of metallic bonding from Na to Al becasue of the strong electrostatic forces between M+ and e- so because there are more delocalised elctrons there is a stronger nuclear charge so smaller ionic radius.

Front 14

Describe the bonding of Silicon/Si?

Back 14

Si is a giant covalent macromolecule and has strong covalent bonds so alot of energy is needed to break the bonds.

Front 15

Describe the following graph?

Back 15

There is an increasing force in van der waals force due to increasing Mr.

except HF which is unexpectadley high due to H bonding.

As you desend the Hydrogen halides increase on boiling point except HF which is unexpectadley high due to H bonding. As VDW increases the strength pf permanent dipole-dipole decreases.

As VDW increases the strength pf permanent dipole-dipole decreases.

As VDW increases the strength pf permanent dipole-dipole decreases.