chemistry

• who is john dalton

  he proposed an atomic theory. his model was a sphere

  
  

  1. all substances made up of atoms
  2. all atoms of same element are exactlu like
  3. atoms join with other atoms to create new substances
• who is jj thomson

  found that atoms contain electrons, he made the plum pudding model. it states that its mostly positive charged material, with negative particles.
• who is ernest rutherford


  proposed the atomn consists of mostly empty space. he discovered electrons orbit
• who is niels bohr

  suggested that electrons travel around the nucleus of an atom. electrons can jump from one oath, to another.
• Who is james chadwick

  discovered that the nucleus contained neutrons.
• what are groups

  numbers 1-18, they go down the table
• what are periods

  they go across the table. there are 7 periods
• structure of table

  group 1- alkaline metals, group 2- alakaline earth metals, 3-12 transition metals, 17 - hallogens, 18 - noble gases
• what is atomic mass

  the number of protons, and neutrons
• what is atomic radius


  the total distance from an atom's nucleus to the outermost orbital of electron. it decreases as you go across a period. this is because as you go across, more protons are added, but the electrons in the valence shell stay the same and draws them in tighter
• what is ionisation energy


  it is the amount of energy required to remove an electron from an isolated atom or molecule. the trend is that it increases from left to right (period)
• what is electronegativity

  a measure of an atom's ability to attract shared electrons to itself. it increases from bottom to top in groups, and increases from left to right across periods
• why do electrons have its own unique colour

  this is becaue of the electrons. the electrons get excited, then drop and release photons.  as each electron moves from a higher energy level (orbit) to a lower one, a different color is emitted. it also depends of the elements it contains
• what is an aas ( atomic absorption spectroscopy)

  it measures the concentration of specific elements in a sample by analyzing their unique "fingerprint" in the form of an atomic absorption spectrum.
• what is the emission spectra

  it is when certain photons can be realeased, and theyre emitted. it is visible light. the electrons get excited, then drop down, they release the extra energy in light
• what is absorbtion spectra

  it is when some photons cant get out, absorbing them, which is the reason for the black lines. it can only absorb the correct energy level. its when electrons get excited, and enrgy is absorbed is equal to the difference in energy, to the higher and lower energy levels
• what are isotopes

  they are an element, with the same no of protons, but different neutrons. they still have the same chemical properties, BUT different physical ones
• what does high concentration mean

  that the light will be dimmer, as more photons are absorbed. vice versa
• what is the mass spectrometer?

  it is used to find the mass of an atom.
• mass spectrometer what does it do?

  particle gets pushed, then only ones with correct velocity will get through, others will crash (electric field) it enters the magnetic field, which moves the ions in circles, seperating the ions, to seperate by mass.