As Chemistry Atomic Structure

Chemistry Cards about Atomic Structure for As Chemistry.

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  • Created by: Pheebie
  • Created on: 08-10-11 09:59

Atomic Mass

The Atomic mass is the average weighted mass, of an atom, of an element, relative to 1/12th of the mass of a Carbon-12 Atom.

Proton; Mass=1, Charge= +1, Position= Nucleus.

Electron; Mass=1/1836, Charge= -1, Position = Around the nucleus.

Neutron; Mass= 1, Charge=0, Position= Nucleus.

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Mass Spectrometer- Ionisation

The first stage of Mass Spectrometry is Ionisation.

An electron gun fires electrons at a vaporised substance to know electrons off it.

X(g) + e- ---> X+ (g) + 2e- or more common... 

X (g) + e-

Doubly Charged Ions can occur but are rare, 

X2+(g) + e- ---> X2+(g) + 4e-

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Mass Spectrometer- Acceleration, Deflection and De

Acceleration is where an electric field is used to speed up particles. F=MA. 

Deflection is where a magnetic field bends the stream of cations. Dependant on the charge and mass. The lighter and more charged they are the easier they are to deflect.

Detection happens when ions start to hit the detector. The more ions that hit the bigger the current is that is produced, and therefore a bigger field is produced.

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Electron Configuration

Hunds Rule:

  • Electrons occupy lower levels and sub levels first.
  • Electrons spread themselves singly in orbitals with in sub levels before they pair up.
  • When they pair up, they spin in opposite directions (up and down.)
  • Each are represented by arrows.

Electron configuration;

Ar: 1S₂, 2S₂, 2p₆, 3S₂, 3p₆.

Ca: 1S₂, 2S₂, 2p₆, 3S₂, 3p₆, 4S₂.

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Ionisation Energies

                    

1st energy= easy to pull of, 2nd, 3rd, etc... harder. 10th= easy to pull off because new shell. Last 2= really hard to remove due to shielding. This shows evidence of levels and sub-levels.

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Ionisation energy across period 3

                    (http://t3.gstatic.com/images?q=tbn:ANd9GcQmejdU6x8ecW-Ea_lKi1oVzTngF-CG64msjuQV9Gw25HMMMCaX)

General upwards Trend because Nuclear charge increases but shielding doesn't change.

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Ionisation energy across period 3 (Mg to Al)

                             

From Mg to Al we have an energy decrease because it's easier to remove e- from 3p than 3s because 3p is slightly shielded by the 3s, so higher energy is needed to remove and electron.

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Ionisation energy across period 3 (P to S)

                       

A pair of electrons in the same orbital repel each other. Sulphur has a pair of electrons in one orbital (Phosphorus doesn't.) So Sulphur  has a lower ionisation energy.

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Across periods.

                  (http://t3.gstatic.com/images?q=tbn:ANd9GcQmejdU6x8ecW-Ea_lKi1oVzTngF-CG64msjuQV9Gw25HMMMCaX)

Large decrease from P2 to P3 because electrons are being removed from higher energy levels.

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Comments

lucy

these are really good, clear and show loads of info for flash cards .. thanks

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