Atomic structure

• The relative mass of a neutron is 1 and the charge is 0
• the relative mass of a proton is 1 and the charge is +1
• The relative mass of an electron is very small and the charge is -1
• The atomic number tells you how many protons there are
• the mass number tells you the total number of protons and neutrons in the atom
• to get the number of neutrons subtract the atomic number from the mass number
• an ion is an atom that has lost or gained electrons
• isotopes have the same number of protons but different number of neutrons
• isotopes have same atomic number but different mass numbers
• compounds are substances formed from two or more elements, the atoms of each are in fixed proportions throughout the compound and they’re held together by chemical bonds
• making bonds involves atoms giving away,taking or sharing electrons
• A chemical reaction is needed to separate a compound
• a compound is formed from a metal and non-metal when they react together this is called ionic bonding
• the metal atoms lose electrons to form positive ions

  the non-metal atoms gain electrons to form negative ions

  the opposing charges mean they are attracted to eachother
• a compound formed from non-metals called covalent bonding
• covalent bonds share electrons
• there’s no chemical bonds in mixtures
• parts of a mixture can be either elements or compounds
• relative atomic mass equation

  
• relative atomic mass


  weighten mean mass of an element
• isotopes have same atomic number but different mass number
• properties of noble gases

  -stable

  -unreactive/inert

  -doesnt form molecules

  -low boiling points

  -atomic mass / density / boiling point increases as you go down group
• what did newlands discover

  Law of octaves
• what is the indivisible atom

  tiny spheres that could not be divided
• what is the plum pudding model

  ball of positive charge with negatively charged electrons embedded into it

  
• what did bohr discover

  electrons orbit the nucleus in shells at specific distances
• what did chadwick discover

  protons make up positive charge and neutrons have a mass but no charge and are found in the nucleus
• what is an atom


  smallest part of an element that can exist
• what is an element


  substance made from one type of atom only
• what is a molecule


  collection of two or more atoms held together by chemical bonds
• What is a transition element


  Metal that is located between groups 2 and 3 of the periodic table

  
• what is Density 


  Measure of compactness

  
• What is a catalyst


  Substance that changes the rate of a chemical reaction without being changed by reaction itself