Chemistry Yr9 Test 2

• Atomic number: The number of protons in an atom ( bottom number)
• Mass Number: The number of protons and neutrons in an atom (top number)
• Location: Proton = Nucleus
• Location: Neutron = Nucleus
• Location: Electron = Outside the nucleus in shells
• Charge: Proton = +1
• Charge: Neutron = 0
• Charge: Electron = -1
• Charge: There are the same number of protons and electrons in an atom so they cancel out and the atom has no overall charge.
• Num of P,N,E: To work out the num of P, N and E the atomic number on the periodic table is the number of protons and neutrons. Then you do the number of protons minus the mass number to. get the num of neutrons.
• Num of P, N and E: Oxygen has a mass number of 16 and an atomic number of 8 how many P, N and E are there?

  P: 8, N: 8, E: 8
• Num of P, N and E: Potassium has an atomic number of 19 and a mass number of of 39. How many P, N and E are there?

  P= 19, N= 20, E= 19
• Quick facts: Chadwick discovered the neutron.
• Quick Facts: Electrons were discovered first in 1897 followed by protons in 1909 then neutrons in 1932.
• Isotopes: Isotopes are atoms of the same element with the same number of protons but different number of neutrons.
• Relative Atomic Mass: Relative atomic mass is the average mass that takes into account the different masses and amounts.
• Relative Atomic Mass:

  sum of (Iso Abun X Iso Mass)

  Relative Atomic Mass = ————————————————-

  sum of all the Iso abundances
• RAM: E.g.

  Copper has two isotopes copper- 63 with an abundance of 69.2% and copper- 65 with an abundance of 30.8%. Calc the RAM to 1 d.p.

  ((69.2 X 63) + (30.8 X 65))

  = ——————————————-

  (69.2 + 30.8)

  = 63.6
• Moles: Number of moles = mass in grams

  ————————

  Relative Mass
• Moles: Mass in grams = moles X relative formula mass
• The conservation of mass is when a chemical reaction occurs and the number and mass of the atoms do not change. The reactants and products mass must be the same.
• Re-arranging word equations: The total mass of the reactants is equal to the total mass of the products.

  Rules are:

  • Balancing numbers can be put in front of formulae.
  • Formulae must not be changed.
• Hydrogen (1):

  1
• Helium (2):

  2
• Lithium (3):

  3
• Beryllium (4):

  2,2
• Boron (5):

  2,3
• Carbon (6):

  2,4
• Nitrogen (7):

  2,5
• Oxygen (8):

  2,6
• Flourine (9):

  2,7
• Neon (10):

  2,8
• Sodium (11):

  2,8,1
• Magnesium (12):

  2,8,2
• Aluminium (13):

  2,8,3
• Silicon (14):

  2,8,4
• Phosophorus (15):

  2,8,5
• Sulfer (16):

  2,8,6
• Chlorine (17):

  2,8,7
• Argon (18):

  2,8,8