SC3, SC4

John Dalton

• All matter is made up of tiny particles called atoms
• Atoms are tiny, hard spheres that can't be broken down into smaller parts
• Atoms cannot be created or destoyed
• Atoms in an element are identical

Atoms can be broken down into smaller parts

• Atom - Smallest Particle
• Element - Made of only one type of atom
• Compound - Two or more different atoms that are chemically joined
• Mixture - 2+ atoms not chemically joined
• Molecule - Two or more atoms chemically joined

                 Mass                   Charge

• Proton         1                          +1
• Neutron       1                           0
• Electron   Neglible                    -1
• These are subatomic particles
• Every atom has atomic number and mass number
• Atomic number = Number of protons in nucleus
• Mass number = Number of protons and neutrons in nucleus
• Outside of nuclues is made of shells of electrons and they fill the shell nearest the nucleus first then work outwards.
• 1st shell holds max of 2 electrons
• 2nd shell holds max of 8 electrons
• 3rd shell holds max of 8 electrons

• Configuration - Distrubution of electrons around atom
• Atomic number = Number of protons
• Number or electrons = Number of protons
• Number of neutrons = mass number - protons or mass number - atomic number
• Isotopes - Atoms with same number of protons but not neutrons
• Relative atomic mass  = (Number of isotope x Percentage in decimal format) + (Number of isotope x Percentage in decimal format).

• Mendeleev arranged elements in order of increasing relative mass. He left gaps for the elements that weren't discovered yet
• He swapped the positions of some elements if he thought their new postiton better suited their chemical properties.
• Non metals are on the right
• Metals are on the left
• Horizontal rows are called periods - Increasing atomic number
• Period tells you amount of shells
• Number of electrons in outer shell = group number
• 

6 = mass number

12 = Atomic number